Modernhydronics february2015de

MODERN HYDRONICS 2015 spring

The financial reality of

operating snow and ice melt systems

Radiant Floors

Design Solutions to meet customer expectations

Closed hydronic system protection

Understanding expansion tanks and system pressure TECHNOLOGY PUMPS OUT SAVINGS RELAYS: HOW DO THEY FIT INTO DESIGN STRATEGIES a publication of

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Contents MH4 WHY DON’T MY FLOORS FEEL WARM?

Simple solutions to avoid the dilemma of unfulfilled customer expectations.

by John Siegenthaler

MH8 A LITTLE MATH GOES A LONG WAY

What you need to know about the financial reality of operating snow and ice melt systems. by Lance MacNevin

MH12 ONES AND ZEROS

How to incorporate relays into your design strategy. by Curtis Bennett

MH16 Product showcase MH22 PRESSURE AND HIGH SCHOOL CHEMISTRY

How the expansion tank protects closed hydronic systems. by Cliff McNeill

MH24 EXPLORING THE AGRICULTURAL MARKET

Biofuel heating system raises profits for organic poultry farmer. by Bill Boss

MH28 SELF BALANCING TECHNOLOGY PUMPS OUT SAVINGS

Precise flow and pressure garner savings in constant and variable systems. by Mike Miller

MODERN Hydronics a supplement of Heating Plumbing Air Conditioning Magazine

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MODERN HYDRONICS

spring 2015

| MH3

>> Radiant

Why don’t my floors feel warm?

Simple solutions to avoid the dilemma of unfulfilled customer expectations.

R

adiant panel heating has matured from the darling of the hydronics industry in the 1990s, into a respected technology that can provide excellent comfort in a range of applications.

Most of you reading this have probably designed and/or installed several radiant panel systems. In many cases those systems involved covering an entire floor area with some type of radiant panel construction detail: slab-on-grade, thin-slab, tube and plate, and so on. This has become standard practice in the industry and it works well when radiant floor heating is installed in houses with average heating loads.

However, as the design heating load per unit of floor area decreases, so does the average floor surface temperature. In a very well-insulated house, the average surface temperature of a heated floor may only be a few degrees above the room air temperature. The reason is that the floor does not need to get any warmer to satisfy the heating load as determined by the setting of the room’s thermostat.

For example: Consider a room with a design heating load of 3000 Btu/hr and a corresponding air temperature of 70F. The room measures 20 ft. by 15 ft. If the entire floor area was covered with radiant panel, the upward heat flux requirement at design load would be:

The average floor surface temperature can be estimated using the following formula:

Where: Tsurface = average floor surface temperature (ºF) q = upward heat flux (Btu/hr/ft2) Tair = room air temperature (ºF) Thus, for the stated example:

This temperature is a few degrees lower than normal skin temperature for hands and feet. The infrared thermograph of a thermally comfortable hand in Figure 1 shows fingertip temperatures in the low to mid 80s.

MH4 | spring 2015

Figure 1 Infrared thermograph of thermally comfortable hand

A floor surface at 75F surface would feel slightly cool to the touch of this hand, even though that floor is releasing sufficient heat to maintain the room at a 70F. Forcing the floor to operate at higher temperatures would quickly overheat the space and likely lead to energy waste due to occupants opening windows or otherwise replacing overheated interior air with cooler outside air.

Also, keep in mind that the 75F average floor surface temperature would only exist on a design day, when outside temperatures are at or close to their lowest values. This average floor surface temperature will be even lower under partial loading conditions.

LOOK ON THE BRIGHT SIDE Even though a heated floor in a low energy use building may not be as warm as a heated floor in a more energy wasteful building, it will still be warmer than unheated floors in rooms heated by forced air systems or fin-tube baseboard.

Furthermore, from the standpoint of thermal efficiency of the heat source, lower surface temperatures are a good thing.

Heat sources such as a condensing boiler, hydronic heat pumps and solar thermal subsystems, will all operate at high efficiency in combination with low water temperatures. The lower the water temperature is, the higher the efficiency of the heat source.

A floor with a surface temperature just a bit warmer than the room air is also less susceptible to overheating due to unpredictable internal heat gains, such as those caused by sunlight, or gatherings of people.

The potential “fly in-the-ointment” is that the owner’s expectation of warm-to-the-touch floors may not be realized. As most of you can attest, unfulfilled customer expectations are

MODERN HYDRONICS

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Modern Hydronics

a problem, even when the heating system is working at peak efficiency.

If the customer was informed that the floors would not feel warm, even though interior setpoint temperature would still be maintained and if they understood and agreed to this operating condition, there should not be any unfulfilled expectations. However, if the customer cannot think past all those cozy barefoot advertisements for radiant floor heating and still expects warm floors regardless of load, the result is likely to be serious disappointment.

The retort “but I paid for warm floors…” will surely be heard and the prospects for a good customer relationship are headed south. The fact that the mod/con boiler you installed is operFigure 2a Radiant design involving partial floor space

Figure 2b Strategic placement of radiant panel

ating at 97 per cent rather than 92 per cent thermal efficiency is probably not going to smooth things over.

I recommend having a serious conversation with clients who are considering the use of floor heating in a low energy use building. Be sure you explain why the floors often do not feel warm to the touch and be sure you listen carefully to any concerns they may have regarding this. If the client’s primal instincts for warm surfaces are very evident, consider offering them some of the following alternatives.

WHEN LESS IS MORE There are several alternatives to “full coverage” floor heating systems that provide a reasonable balance between heat source efficiency and the owner’s desire for warm surfaces.

One is to make the surface area of the radiant panel smaller by not covering the entire floor area with tubing. If the size of the radiant panel in the previous example were cut in half, the necessary upward heat flux would increase from 10 to 20 Btu/hr/ft2. This would bring the average floor surface temperature under design load conditions from 75 up to 80F. This warmer floor surface temperature is more likely to appease those looking for “barefoot-friendly” floors. Reducing the panel area to one third of the room’s floor area would boost the average floor surface temperature under design load conditions to about 85F, a recommended maximum for floors on which there is prolonged foot contact.

The design approach of not covering the entire floor area with tubing was common in the days when copper tubing was used for radiant floor heating installations (see sidebar). Each radiant panel was sized to the room load assuming a specific upward heat flux and specified supply water temperature.

A room with half the heating load of another room would get half as many square feet of panel area. Assuming floor coverings of comparable R-value, this approach allows the system to work with a single supply water temperature and eliminates the need for multiple mixing devices.

Another option that integrates well with low energy use continued on pMH6 Figure 3 Low mass radiant ceiling construction

RADIANT PANEL SIZING BASED ON SUPPLY WATER TEMP I used the design approach of not covering the entire floor area with tubing when designing the floor heating system in my own house in 1979. Figure 2a and Figure 2b show images of the floor heating panel in our dining area. The panel was constructed using 3/8-inch copper tubing because PEX tubing was not available in North America at the time. We installed the radiant panel under the eventual location of the dining table, right where our feet rest on the floor. It feels great on a cold winter morning.

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MODERN HYDRONICS

spring 2015

| MH5

>> Radiant continued from pMH5 Figure 4 Panel radiator operating at a relatively low water temperature

buildings is radiant ceiling heating. Most heated ceilings deliver 95+ per cent of their heat output as thermal radiation.

They “shine” thermal radiation down into the room much as a light fixture shines visible light downward.

Low mass radiant ceilings, such as the construction shown in Figure 3, can quickly warm up following a cold start. They are ideal in rooms where quick recovery from setback conditions is desirable. Low mass also means they can quickly suspend heat output when necessary, which helps limit overheating when significant internal heat gains occur.

For a ceiling panel constructed as shown in Figure 3, an average water temperature of 110F can deliver a downward heat output of about 28 Btu/hr/ft2. Consider this panel installed in the low energy use building with a design heating load of only 10 Btu/hr/ft2. The panel would only have to cover about 36 per cent of the ceiling area to deliver the required heat output. This significantly reduces materials and installation labour costs. It also allows low temperature heat sources to achieve high thermal efficiency.

Another option is a system using panel radiators rather than site-built radiant panels. Panel radiators are available in a range of sizes and shapes and a correspondingly wide range of heat output ratings. The most common design approach is to size a single panel radiator to the design load of a typical room such as a bedroom, bathroom or kitchen. Larger spaces may require more than one panel radiator piped in parallel.

My suggestion is to size each panel radiator in the system to

provide the design heating requirement of its assigned space, while operating at a supply water temperature of no higher than 120F. This keeps the operating efficiency of low temperature heat sources high. It also increases the percentage of radiant versus convective heat output and eliminates any safety concerns about occupants touching excessively hot surfaces.

A panel radiator with a surface temperature in the range of 100 to 115F will inevitably have people cozying up to it in cold weather. It will be a place where damp mittens, gloves and hats get placed for a quick drying. Perhaps most importantly, it provides a solution for those times when you just want to put your chilled hands, feet, or derrière against a warm surface.

Figure 4 is an infrared image of a panel radiator operating at a relatively low water temperature. Notice the temperature gradient from top to bottom and how it is relatively uniform across the face of the radiator. That is evidence of a welldesigned product.

NO WORRIES I will leave you with a final thought on lower surface temperature heated floors. It comes from seeing how people that I have accompanied over the years have reacted when first told they are in a space with a heated floor. Many will squat down, put their hand on the floor and then stand up with a confused look on their face. They then say something like “the floor doesn’t feel warm.”

The question I then ask is: “Are you comfortable?” To which most answer “Yes,” or maybe even “Yes, I’m very comfortable.” The final advice I then offer is: “If you’re comfortable, don’t worry about how the floor feels.” Try it the next time you introduce someone to radiant floor heating. <> - John Siegenthaler John Siegenthaler, P.E., is a mechanical engineering graduate of Rensselaer Polytechnic Institute and a licensed professional engineer.

He has over 34 years experience in designing modern hydronic heating systems. He is also an associate professor emeritus of engineering technology at Mohawk Valley Community College in Utica, NY. Editor's Note: See John at Modern Hydronics-Summit 2015 in Toronto on September 10, 2015 (see pMH10 for more information).

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MODERN HYDRONICS

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>> Snow and Ice Melt

A Little Math Goes A Long Way What you need to know about the financial reality of operating snow and ice melt systems.

H

ydronic snow and ice melting (SIM) systems have been around for decades, but some building owners are missing out on the benefits of these systems because they assume operating costs will be too high. Many are surprised to find that the annual operating costs for a SIM system can be less than for mechanical snow removal, using snowblowers or snowplows.

This article tackles the delicate topic of trying to estimate operating costs based on historical weather data, energy costs and some math. We will walk through the estimating process using a specific example. Note that we use “estimate,” not “predict.” Until weather forecasters guarantee the weather, operating costs cannot be guaranteed.

The process to estimate SIM system operating costs involves three steps: 1. Determine annual energy usage in Btus or kWh. 2. Calculate the cost of energy in $/Btu for the specific fuel available.

3. The annual operating cost is simply Annual energy usage x cost in $/Btu. If this seems too simple, let’s look at an example. The location of this example is anonymous, but the parameters chosen correspond with many Canadian locations.

MH8 | spring 2015

step 1 Here is the method to determine annual energy usage with some design details left out, and all assumptions stated: A. Operating load: Size the system output for the correct design load.

• The example uses 150 Btu/ft2 per hour (many operational hours will not even need this many Btus).

• This article is not focusing on sizing the system, but typical values across applications range from 75 Btu/ft2-hr to 225 Btu/ft2-hr.

B. Melting time: Research how many hours per year the system is expected to operate.

• Environment Canada has some of this data available; look for hours of snowfall.

• It could be 150, 200, or more, depending on the location.

C. Pick-up energy: Know the typical “cold-start” temperature for the heated area, and the specific heat of the thermal mass type. In many regions, the coldest days are not the snowy days.

• A common snowfall temperature is -10C (14F), sometimes warmer.

• For poured concrete 15 cm (6 in) thick, the concrete requires 15 Btu per ft2 per ˚F to warm up, based on the “specific heat” of concrete of 0.23 Btu/lb-˚F.

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D. Number of events: Estimate how many snowfalls per year will occur, as energy may be required to warm the heated area each time, depending on the controls scenario (coldstart versus idling versus always-on).

E. Calculate annual energy demand: • First, for pick-up loads (i.e., warming the slab X times) • Then, for operating (i.e., melting and evaporating) • Add these together (energy for idling will be addressed later).

Table 1 Comparison of energy costs for common fuels (expressed as net cost per million Btus of heat energy)

Sample Project

A commercial building has a 90 m2 (1 000 ft2) parking garage ramp, which is made of poured concrete 15 cm. (6 in.) thick embedded with 3/4 in. diameter PEX pipes at 20 cm. (8 in.) spacing.

1. The designer selects a system that requires an output of 150 Btu/ft2 per hour including reverse loss and edge losses to the cold ground.

• The total SIM operating load = 150 000 Btu/hr (simply 1 000 ft2 x 150 Btu/ft2-hr) • Assume

no standby losses due to well-insulated pipes carrying fluid to the manifold, and simple math 2. Location’s estimate for snow or ice is 200 hours per winter.

3. Typical temperature at start of snowfall is -10C (14F), though some days are warmer.

• E ach time the concrete is warmed, it will take approximately 400 000 Btu of energy (math not shown) 4. This snowfall will occur over 25 events through the winter.

• System will turn on 25 times.

• System will run for an average of eight hours per activation (200 ÷ 25 = 8).

5. Now we add things up: • Annual pick-up load is 25 x 400 000 Btu = 10 million Btu/year for ramp warming.

• Annual operational load is 150 000 Btu/hr x 200 hrs/year = 30 million Btu/year for melting • Total annual load is 10 million + 30 million = 40 million Btu/year This sounds like a lot, but how much does it actually cost to produce and deliver 40 million Btus? This brings us to Step 2. step 2 Here are the steps to calculate the cost of energy in $/Btu, with all assumptions stated: 1. Decide what type of fuel (natural gas, fuel oil, and so on) will be used and its cost. Research the energy content of that fuel (see Table 1).

2. Determine the efficiency of the heat source, if there is one (some SIM systems use waste heat).

3. Use the equation below to get the net cost per million Btu delivered.

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Sample Project

1. Fuel: Select natural gas @ $0.30/m3 net fuel cost – be sure to know the local fuel cost 2. Energy: 1 m3 natural gas contains 36 000 Btu (this is fixed) 3. Heat source: We will use a condensing boiler running at 93 per cent combustion efficiency on average 4. Net cost per million Btu = $9.00/million Btu step 3 Calculate the annual operating cost by multiplying the annual load by the net cost per million Btu: 40 million Btu/year x $9.00/million Btu = $360/year That is an annual operating cost of $360 and this is a fairly capable system, suitable for most residential and many light commercial applications. Obviously, each system must be designed and estimated individually. The annual operating cost will be higher for more expensive fuels, but this can be determined using the same process.

IDLING ENERGY If the SIM system used an idling strategy to keep the slab warm in between snowfalls, be aware that the extra energy continued on pMH10

selling the system Imagine you are talking with a client about hydronic snow and ice melt as a winter maintenance option. Compare $360 with an annual snow removal contract estimate of $100 per snow fall ($2,500 per year) for plowing with a truck-mounted scraper, which may damage outdoor surfaces. Afterward, someone must do the salting and sanding. And where do you put all the snow?

In this example, the hydronic SIM system is more than 80 per cent less expensive to operate over the winter than relying on mechanical snow removal. In other words, the SIM system costs roughly one-seventh as much each winter to operate while providing convenience, safety and protection of outdoor surfaces. And with an advanced control system, it is fully automatic and starts working at the first snowflake.

MODERN HYDRONICS

spring 2015

| MH9

>> Snow and Ice Melt continued from pMH9 consumed between snowfalls could increase operating costs by a factor of four, five or six, depending on the location. However, this could still be less expensive than $2,500 for mechanical removal.

projects. Among these are: convenience of automatic snow and ice removal; increased safety for residents and visitors with reduced liability exposure; minimized environmental impact with no de-icing chemicals entering waterways; reduced mainteUSING WASTE HEAT nance costs on both outdoor and Some facilities generate waste heat indoor surfaces; and the freeing up of that needs to be rejected using chillbuilding maintenance staff and buders or geothermal heat pumps durgets for more productive tasks.

With advanced controls the SIM system ing portions of the year. Examples When all of the factors are considis fully automatic. include office buildings, factories, ered and presented effectively, many hockey rinks and car dealerships with waste-oil boilers. In facility managers will appreciate that the benefits of hydronic these applications, an always-on SIM system can be an effiSIM systems greatly outweigh the costs. <> cient and effective solution for rejecting the excess heat, - Lance MacNevin while providing all the benefits of a hydronic SIM system.

Lance MacNevin is the manager of REHAU Like most things in the hydronics industry, using some math Academy where he is responsible for training removes a lot of mystery. In this case, the math clearly shows across North America. With over 20 years of that snow and ice melting systems are economical and affordhydronic experience, he is on the technical comable uses of hydronics technology. mittee for CSA B214. He can be reached at Beyond the math, there are many other reasons to consider lance.macnevin@rehau.com. using hydronic SIM in residential, commercial and institutional

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For more information contact Kim at krossiter@hpacmag.com MH10 | spring 2015

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>> Controls

Ones and zeros How to incorporate relays into your design strategy.

Since this is the introductory Ones and Zeros article, it is best to go back to when the controls world started to get a little more interesting with the introduction of the electromechanical switch, or the relay as it is better known. It is a device that really did change the world. While simple, it can still make or break your control strategy.

Generally, if you know the details of how something works you are better able to visualize when you design with it. The same is true of relays.

making ones and zeros into words, moving them back and forth, turning those words into decisions and running Google.

None of this would have been possible without relays.

Figure 2 Energized is a term that means we have applied power to the coil and the switches are in the ON position. Un-energized is the opposite, meaning the switches are in the OFF position and there is NO power applied to the coil.

L

ove it or hate it, the relay is here to stay. Binary code, which is just a series of ones and zeros, is the base language of all computers and can be done with relays. In fact, the first computers were built with only relays. Scientists would use thousands of relays turning on and off to do simple calculations such as adding and subtracting.

Computers at their very essence are just billions of tiny relays Figure 1 Electromechanical switch

MH12 | spring 2015

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â&#x20AC;&#x153;It is a device that really did change the world. While simple, it can still make or break your control strategy.â&#x20AC;?

BASIC BUILDING BLOCKS The relay is an electromechanical switch with two sections. In its simplest form, a coil and a switch. When the coil is energized the switch moves, creating a contact closure moving the electrical signal from one point to another. The coil is the portion of the relay that is the electrical and the switch is the mechanical part. When voltage is applied to the coil it creates a magnetic field, which pushes or pulls the switches (see Figure 1).

Think of the coil as that experiment that we all did in grade three science; the one in which we wrapped a nail with wire and connected each end of the wire to a battery. By doing this we created an electromagnet that could be used to pick up pieces of metal. The metal pieces would fall off when the battery was disconnected.

The coil of the relay works with these same principles. When we apply power the switch moves one way and when we take the power away the switch moves back to where it started.

THE INNER WORKINGS Relay coils can be made to energize from DC voltage or AC voltage. DC voltage relays are generally used on circuit boards.

AC coil relays are the main choice in our industry. The primary reason is that those voltages are readily available in the boiler room. These voltages are 24VAC and 120VAC. The next section of the relay is the poles and throws. I am sure you have been in a boiler room and heard the expression double pole double throw. That is a very common relay type and refers to the relay having two switches, each having a normally open (N/O) and normally closed (N/C) connection on each switch (see Figure 2).

Pole basically means the number of common terminals there is on the relay or the number of switches it has inside.

Throws mean the number of directions the switch can move. If it is a single throw, the relay switch can only move in one direction and generally only has an N/O terminal. If it is a double throw the switch can move in both directions and the relay has an N/O terminal and an N/C terminal. There are different reasons that we would use the N/O terminal and not the N/C terminal. We will elaborate on that but this gives us a good understanding of the inner working of the relay.

HOW WE USE RELAYS If you take away only two tidbits from this article let it be these.

Firstly, coil voltages can be different than pole voltages and that can create some confusion. Secondly, remember that a relay can have different voltages on different poles.

To clarify, start with a 24VAC double pole double throw relay.

Remember that the 24VAC is the coil voltage rating. When we apply 24VAC the relay energizes, closing the N/O terminal and completing the circuit from the common terminal to the N/O terminal. At the same time the N/C connection opens stopping the connection from the common terminal to the N/C terminal. The pole can only connect to one terminal at a time. Either the common connects to the N/O terminal or the N/C. A pump could be running on the first pole, which would use 120VAC and a valve could be running on the second pole, which would use 24VAC. This is also a very good reason why more than one pole relays are used so the same coil can be used to push and pull multiple switches inside the relay. Otherwise we end up with a real mess of relays in the boiler room. continued on pMH14

Figure 3 Relay used to take 24 VAC Coil Voltage

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Figure 4 Control output to energize the coil

MODERN HYDRONICS

spring 2015

| MH13

>> Controls continued from pMH13 Figure 5 DHW application

Figure 6 Heat pump application

So, where do we use relays? Relays can be used to take a 24VAC coil voltage to make a pump turn on. They can be used when the pump output on the control is not big enough to run either that pump or you are trying to run two pumps at the same time. As mentioned previously, coil voltages do not have to be the same as pole voltages. So, in this case we can apply 24VAC to the coil and run 120VAC through one of the poles to make a pump turn on when we energize the coil.

There may be many devices to energize the coil, like an endswitch on a valve, because in that case the end-switch would not be able to handle the current needed to run the pump so a relay is used (see Figure 3).

Relays are also used in cases where we may need to turn on a valve with 24VAC and a pump on with 120VAC at the same time. We could take the coil signal from a control, but the control only has one output. In this case, we would use the control output to energize the coil to turn both the valve and the pump on at the same time. This is where most of the “slip ups” in relay logic occur (see Figure 4).

The most difficult part of relays would be using them for interlocking or, in other words, turning one device on when the coil energizes but at the same time turning another device off. An example of this might be in DHW. Keeping in mind that in different regions system designs differ, but in situations where both the system pump and the DHW pump are able to pump through the boiler some controls can do this automatically, while most non-condensing boilers cannot. This control scheme must be done externally. In this case the system pump would be normally on if the control needed it on but if the DHW calls it will turn off the system pump and run only the DHW pump, essentially prioritizing it (see Figure 5).

This is a little more complicated than it looks. The line voltage for the system pump actually comes from the pump output on the control. Two things have to happen for the system pump to be able to come on. Firstly, the system pump output from the control must turn on and secondly the aquastat cannot be calling. You will notice that we are using the N/C terminal for the system pump. This is because we want the system pump to “be able” to come on when the aquatsat is

not calling. If the aquatsat calls, the N/C terminal will open, turning off the system pump and the N/O terminal of the second pole will close, turning on the DHW pump.

In the heat pump world there are complicated strategies that always require relays. An example of this is where an installation has only one heat pump and one boiler. In winter there is generally no need for cooling, so using the heat pump and the boiler together is easy. In the summer when the heat pump is used for cooling the heat pump cannot do both heating and cooling at the same time.

While the heat pump is cooling there is no way to make hot water. In this case a relay would be used from the reversing valve or cooling contact on the thermostat, to direct the heating call to the boiler. In the summer or when the heat pump is cooling and we get a heat call, the relay will turn the boiler on instead of using the heat pump in heating.

To add another twist, the boiler needs dry contact so the 24VAC signals have to be isolated from the boiler. A relay will be necessary to accomplish this as well. A dry contact is essentially just using the switch of the relay without adding 24VAC or 120VAC to the common terminal.

We would use the common and the N/O terminal so that the device we are connecting to sends its own voltage or signal through the relay. In this case we would most likely either blow the transformer on the boiler or the transformer feeding the thermostat if we did not isolate and make a dry contact (see Figure 6).

At the end of the day control options are getting better at offering solutions and outputs for all applications but there are always those contractors who like to push the envelope and do something slightly different. For that, luckily we have relays. <> - Curtis Bennett

MH14 | spring 2015

A graduate of Southern Alberta Institute of Technology (SAIT), Curtis Bennett, C.E.T., is operations manager and a product developer at HBX Control Systems in Calgary, AB. He can be reached at curtis@hbxcontrols.com. Look for more electronics and controls articles by Curtis in future issues.

MODERN HYDRONICS

www.hpacmag.com

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Reinvent your thinking about boilers at BoilersMadeSmart.com or Navien.com.

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C O N D E N S I N G

T E C H N O L O G Y

>> Products Sterling HVAC's Xcelon system is a rooftop make-up air unit that combines hydronic condensing boiler technology with advanced air distribution and heat recovery methods, for levels of efficiency up to 98 per cent. Available with a 800-1200 MBH heating capacity, Xcelon uses a factory charged, closed loop 35 per cent glycol mix for freeze protection with no separate water supply required. It can offer airflow of 4501-10 000 CFM. www.xcelonhvac.com

Eco King Supreme Boiler and Combi boiler is an extremely user and installer friendly hot water heating boiler. Made in the NethCrown Boiler Co. has launched the Phantom, a

erlands there are two models and sizes ranging from 100 to

stainless steel, condensing boiler with a water

200 000 Btu. Both models provide space heating and domestic

tube heat exchanger. Available in five wall-mount

hot water either via an external indirect tank or on demand hot

sizes - 80, 100, 120, 150, and 180 MBH - with

water with the Combi model. Integrated pump, expansion tank,

four more sizes (210, 285, 399 & 500 MBH)

self regulating gas valve, outdoor sensor, and automatic air vent

available as floor-mount boilers in the Phantom-

make the Supreme an easy to install and service boiler.

X line, the boiler comes with a touch screen

www.ecokingheating.com

user interface. Features include a modulating burner with a five-to-one turndown ratio, an intelligent boiler control and standard outdoor reset function. www.CrownBoiler.com

Caleffi’s Discalair is a high discharge and high performance automatic air vent. It has a unique and rugged pin-guided float for reliability in tough vertical installations. The Discalair is 100 per cent serviceable; the internal float/vent assembly can be replaced if it

REHAU's Smart Controls SIM Module is a weather-sensing con-

becomes damaged. Vent cap choices offer additional

trol option developed for use with its hydronic snow and ice

flexibility. A high venting capacity of 1.8 scfm at 20 psi

melting (SIM) systems. Automatic pre-idle of the slab based on

and 3 scfm at 50 psi with ½ in. fnpt connection make

Environment Canada forecasts allows for a range of idle tempera-

it best suited for medium-to-large installations.

tures to be established based on the confidence interval of the

www.caleffi.us

forecast. An unlimited number of snow melting zones enables the system to scale to handle the demands of large commercial projects. Zone priority scheduling, based on real-time boiler capacity, enables crucial areas to be cleared first. Individual slab melt-point temperature settings for each zone accommodate various slab constructions. Secure remote access through the Web provides full user control at any time from any Internet-enabled device. The SIM module can be used independently or integrated with a REHAU Smart Controls indoor comfort control system. www.na.rehau.com/controls

Aermec's water to water chiller is designed to meet simultaneous heating, cooling and domestic hot water production demands in commercial and institutional applications. Designed for two and four-pipe systems, NXP models are available with a built-in hydronic kit and are offered in capacities ranging from 31 to 142 tons. The automatic microprocessor control offers automatic rotation of scroll compressors and pumps based on operating hours. A programmable time-clock continuously adjusts operation to reduce energy consumption. NXP also allows serial connection with BACNET, MODBUS and remote control through a standard PC with Ethernet connection. www.aermec.com MH16 | spring 2015

MODERN HYDRONICS

continued on pMH18 www.hpacmag.com

>> Products continued from pMH16

An electronic tempering valve control with Safeguard from Heat-Timer Corporation is packaged with a stainless steel valve body and an electronic actuator. When the temperature

Viega's new line of control products includes

reaches a critical point, the control activates

the compact 0-10V DC Powerhead (shown

an optional solenoid valve to close the hot wa-

here), 0-10V DC Actuator, a Zone Valve and

ter supply. In addition, it can trigger two alarm

thermostat. The powerhead, which provides

outputs. The ETV-Plus connects to an existing

short response times and self-calibrates ev-

Heat-Timer control equipped with the Internet.

ery 24 hours, features a plug-in connection

An optional Internet Communication Module is

cable and 360-degree installation position.

required. System critical alarms may be sent

The actuator provides short response times

Camus has introduced the Advantus boiler a

by e-mail or text message. With the optional

for improved control response for radiant sys-

two-pass counter-flow fire tube heat exchanger.

BACnet Communication Module, the control

tems. Viega ProPress and PEX Press adapters

Designed to offer thermal efficiencies of up to

connects to the BACnet MSTP networks giving

are supplied with the zone valve. A thermal

99 per cent in low water temperatures, it has a

you the capability to change settings and moni-

electric motor allows for simplified wiring in

turn down ratio of up to 25:1. The unit is avail-

tor sensors. www.heat-timer.com

two- and four-wire applications. The thermo-

able in 13 models with inputs ranging from

stat has intuitive, menu-driving programming

450â&#x20AC;&#x2030;000 to 4.0 mil. Btu/hr.

and icons for easy use. The thermostat inte-

www.camus-hydronics.com

grates with a variety of equipment and mounts to drywall or junction box with colour-coded wire connections. www.viega.us

The Beckett GeniSys intermittent pilot gas ignition control is a 24 Vac primary safety control designed for use in residential and light commercial gas heating applications that use an intermittent pilot for lighting the main burner.

It includes an integrated spark ignition coil for lighting the pilot and uses flame rectification

Webstone's lead free Pro-Connect ProPush

International Environmental Corp. has intro-

principles to prove the presence of the pilot

products have a 10 for 1 guarantee, meaning

duced its Vertical Classic (F*C) Series, featur-

flame. Designed for use in single rod and dual

that if the product fails as a result of a manu-

ing flexibility and customization capabilities,

rod applications, the units feature four LEDs

facturing defect, the manufacturer will replace

while providing key new elements that improve

for improved diagnostics, continuous retry

the unit tenfold and reimburse the installing

indoor air quality, enhance system performance

standard (single or multiple trials for ignition is

contractor up to an additional $50 towards

and minimize maintenance. Offering a 65- to

optional), mounting using screws or fasteners,

their labour. The solder-free line is offered in

85-per cent efficiency range, Vertical Classic

selectable ignition and pre-purge timing, and

bulk or individual packaging and is compatible

Series fan coil units include an Eco-telligent

selectable relight or recycle operation. The mi-

with copper, PEX, or CPVC systems. Forged

ECM motor. The units' high-performance

croprocessor is checked for proper operation

from dezincification resistant brass and cUPC

hydronic coils also average 25-per cent greater

before each cycle. Model 7586C has a manual

certified to NSF/ANSI 61-8, the line is suited

AHRI-reported capacity than those of the previ-

reset button and non-volatile lockout.

to potable water and hydronic heating systems.

ous-generation Vertical Series from IEC.

www.beckettcorp.com

www.webstonevalves.com/proconnect

www.iec-okc.com

continued on pMH20 MH18 |

spring 2015

MODERN HYDRONICS

www.hpacmag.com

TA SERIES 7CP PRESSURE INDEPENDENT BALANCING AND CONTROL VALVE

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Designed to save energy Benefits: •

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TA Series 7CP is a pressure independent balancing and control valve with integrated flow and measurement capabilities to achieve ultimate energy savings with highly reliable system operation.

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Unique measuring of flow, pressure drop and available pump head for easy commissioning, pump head optimization and easy detection of system failures

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For sizes ½ – 1¼" | 15 – 32 mm (Part of a complete Victaulic pressure independent balancing and control valve solution up to 6" | 150 mm)

victaulic.com/balancing

Victaulic is the exclusive North American representative for IMI Hydronic Engineering’s IMI TA product brand.

8603 REV A 01/2015 Victaulic and all other Victaulic marks are the trademarks or registered trademarks of Victaulic Company, and/or its affiliated entities, in the U.S. and/or other countries. The terms “Patented” or “Patent Pending” refer to design or utility patents or patent applications for articles and/or methods of use in the United States and/or other countries. © 2015 VICTAULIC COMPANY. ALL RIGHTS RESERVED.

>> Products continued from pMH18

The Stiebel Eltron Accelera 300 heat pump water heater can extract up to 80 per cent of its energy requirements from the energy in the air around it.

The compressor and fan consume one kWh of electricity to generate the heat equivalent of three to five kWh. The low power consumption (500 W heat pump, 2200 W including back-up element) makes The

Creek

XL

the unit a viable option for connecting to a photovol-

boiler from Su-

taic system. It is Energy Star certified for Canada.

perior is part of

www.stiebel-eltron-USA.com

the Creek condensing boiler family and starts at 2 000 000 Btus, up to 5 500 000 Btus. The boiler offers a high water volume for easy adaptation to

Available in 1.0, 1.5 and 2.0 million

existing piping systems and multiple piping configurations. Due to its

Btu/h sizes, and delivering up to 96.1

high mass, the boiler has a low waterside pressure drop which helps

per cent combustion efficiency, Weil-

reduce electrical consumption from the system pumps. The boiler

McLain's SlimFit boiler is a compact

design has two return connections making it suitable for multi-loop

unit with an aluminum heat exchanger.

systems. Access to the furnace is provided by a hinged front door.

Designed for commercial applications,

Models also feature a second front door at the bottom for increased

the boiler is fully-factory assembled.

access. Waterside inspection points are also provided.

Features include a fully customizable

www.superiorboiler.com

outdoor reset curve, lead/lag capability with up to eight boilers with lead boiler rotation, remote modulation through BAS using Modbus or BACnet and high limit temperature control with manual reset. www.weil-mclain.ca Lochinvar, LLC has expanded its line of Crest condensing boilers to include three new models with 750 000, 1.0 million and 1.25 million Btu/hr inputs. Featuring Wave fire-tube design and advanced combustion technology, the boiler models deliver 96.2 per cent thermal efficiency and up to 20:1 modulation turndown.

Designed with a top-mounted micro-metal fibre burner, the system modulating combustion from as low as five per cent of the maximum firing rate up to 100 per cent as heating load increases. The boiler's Smart Touch control can be integrated directly into a building automation system through BACnet MSTP, ModBus and other communication protocols using a gateway device. www.Lochinvar.com

MH20 | spring 2015

MODERN HYDRONICS

www.hpacmag.com

Pumps are complex systems in which every detail is crucially important. Our test procedures analyse every single aspect. This allows us to continuously optimise the performance and lifespan of our excellent product portfolio.

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>> System Design

Pressure and high school chemistry How the often misunderstood expansion tank protects closed hydronic systems.

T

SIZE MATTERS he residential expansion tank is In the age of modern hydronics, expansion one of the most important and tanks come in many sizes and shapes. How least understood components of do we make sure that we have the right exa properly functioning hydronic pansion tank for our system? What does it heating system. We speak about it indimean to have the “right” expansion tank? rectly and by now everyone in the industry Essentially “right” in this case is not wrong, can repeat the following in their sleep: “aland the only wrong tank is an undersized ways pump away from the expansion tank. So size does matter. As for shape, tank” and “the expansion tank is the point of no pressure change.” But how many of that comes down to personal preference.

An expansion tank typically comes with us truly understand the expansion tank instructions, which describe what type and how it relates to system pressure?

And where does high school chemistry Expansion tanks come in many shapes and size of system that it is suitable for.

There may be a table that shows some come in? and sizes. typical system types such as radiant floor, We will come to high school chemistry in a bit, but first, let’s start by asking a few questions such as: baseboard, or radiators along with typical boiler sizes (see Table 1). Now here is the interesting part. This table could Why do we need an expansion tank and what size of tank do have been put together by a group of high school chemistry we need? students.

Here are some basic answers. When water or a glycol/waThink back to when you were sitting in your high school ter mixture is heated it expands. If a liquid expands in a conchemistry class while your teacher rambled on about guys by fined space, such as a closed hydronic system, the pressure in the names of Boyle, Charles, Gay-Lussac and Avogadro, along the confined space will increase and it will increase drastiwith a couple of things called the Ideal Gas Law and the cally. The increased pressure will look for the easiest path Combined Gas Law. Do not worry if you can’t remember all of for release. Hopefully, this will be a pressure relief valve and this stuff. I didn’t either, until I walked past my son as he was not a weak component in the system that may be of vital studying his high school chemistry and suddenly realized that importance. some of that stuff was actually useful in real life. (I also stopped We use expansion tanks to prevent this drastic build up of to take a look because it is such a rare sight to see a high school pressure in closed hydronic systems. But every once in a while, student actually studying.) it does not seem to work the way we expected it to. Sometimes, There may have even been a question in your textbook that the pressure still changes more than we think it should. This is read something like this. “If you have a closed system with 15 when we need to take a look at the expansion tank and try to gallons of water and two gallons of air separated by a rubber understand it better.

Table 1 Sample expansion tank sizing chart

MH22 | spring 2015

Finned Tube Baseboard and Radiant ZHT8 ZHT8 ZHT18 ZHT18 ZHT18 ZHT18 ZHT24 ZHT24

MODERN HYDRONICS

Cast Iron Baseboard ZHT8 ZHT18 ZHT24 ZHT24 ZHT24 ZHT50 ZHT50F ZHT50F www.hpacmag.com

Table: Zilmet

Boiler Net Output (1000's of BTU/Hr) 25 50 75 100 125 150 175 200

Type of Radiation Convection and Cast Iron Unit Heaters Radiators ZHT8 ZHT8 ZHT8 ZHT18 ZHT18 ZHT18 ZHT18 ZHT24 ZHT24 ZHT24 ZHT24 ZHT50 ZHT24 ZHT50F ZHT24 ZHT50F

Modern Hydronics

diaphragm at room temperature with an initial pressure of 15 psi, what will be the final pressure in the system if the temperature is raised to 180 degrees Fahrenheit?” That is right, this question is a cleverly disguised hydronic heating system with an expansion tank. At age 16, we had no clue. At age 16 plus a lot, it now makes sense.

Go and dig out your old chemistry text and find the right formulas − you will find that the end pressure is about 22 psi. If you were to increase the volume of air in the system from two to six gallons, the end pressure would be only about 17 psi. So the larger the expansion tank, the smaller the change in the pressure of the system as it heats up.

If we increase the volume of water in the system from 15 to 30 gallons, the two-gallon expansion tank would have an end pressure of 35 psi. At which point, the typical 30 psi relief valve would have opened to relieve the excess pressure. The six-gallon expansion tank would have a final pressure of 20 psi. All of this can be figured out using a high school chemistry text.

Photo Crown Boiler

WHAT ABOUT THE PRE-CHARGE? Now that we can see how the volume of our expansion tank, the volume of the system and the change in the temperature are all related, let’s take a moment to look at the pre-charge of the expansion tank. How many installers actually check or adjust the pre-charge of the expansion tanks in their systems? I would say probably not very many. The good news is that for the majority of the residential systems that are installed, you do not need to adjust your expansion tank.

Fortunately, the expansion tank makers, the boiler fill makers and the glycol feed makers are all on the same page. In a typical installation, the boiler fill or glycol feed is connected to the system piping at almost the same point as the expansion tank. Expansion tanks typically come with a “pre-charge” of 12 to 14 psi and the boiler fill makers and glycol feed makers also pre-set their equipment to about 12 psi. Now 12 psi is good for hydronic systems in which the highest point in the system is up to 20 feet above the expansion tank. If the highest point in the system happens to be more than 20 feet above your expansion tank, then you will need to consider increasing the fill pressure of your system and increasing the pre-charge on the expansion tank accordingly. The biggest thing to remember when changing the pre-charge on an expansion tank is to do it before it is connected to the system. If you increase the system pressure while the expansion tank is connected, system fluid will be forced into the expansion tank, effectively reducing the tank’s overall capacity.

LONGEVITY Here is a question that I have heard in the past. Why don’t expansion tanks last as long as they used to in the good old days?

This is an excellent question since the basic design of an exwww.hpacmag.com

The residential expansion tank is one of the most important components of a hydronics system.

pansion tank has not changed since the good old days so here is something to think about. Let us take a look at how a system operated back then and how a system operates today.

Systems used to operate hot. We turned them on in the fall, the boiler came up to temperature and then cycled up and down 10 or 20 degrees for six, eight or 10 months at a time.

The expansion tank would make one big flex when the system turned on and heated up from room temperature to its operating temperature. It would then move slightly back and forth with the small changes in temperature. In essence, the expansion tank did not have to flex very much.

In today’s systems, we use outdoor reset controls, cold start boilers, priority for DHW, load shedding and a number of other energy saving features. These developments are great for our utility bills, but the expansion tanks have to flex a lot more. To avoid that increased flex, consider moving to a larger-sized expansion tank.

As we continue to change how we operate systems, it may be time for us to revisit some more of our high school textbooks. Who knows what useful tidbits we might find. <> - Cliff McNeill Cliff McNeill is with Equipco Ltd. at its Calgary, AB office. He joined the manufacturers rep firm in May 2008, bringing with him an extensive background in hydronics, heating, controls and plumbing. A graduate of UBC, McNeill has been a speaker at trade shows across Canada.

MODERN HYDRONICS

spring 2015

| MH23

>> Renewables

Exploring the agricultural market Biofuel heating system raises profits for organic poultry farmer.

P

oultry and livestock products are big business.

Canada’s red meat industry had annual shipments worth $16.3 billion in 2013, with poultry and egg products contributing $4.0 billion in the same year.1,2 In 2011, Canada had 205 730 census farms.3 Opportunities to utilize hydronics within this segment are plentiful.

Heating systems in this market must be reliable and provide consistent temperatures. Chickens in particular require precise temperatures as they need to keep gaining weight to go to market as fast as possible. Precise temperature balancing is critical in each of the 45 x 500 ft. (14 x 152 metre) houses Zimmerman uses for broilers, chickens specifically raised for meat production.

“Chickens are affected by temperature,” observed Matt Aungst, co-owner of the firm that engineered a heating system for organic poultry farmer Earl Ray Zimmerman. “A change of just a few degrees affects the birds’ eating habits. And if they don’t eat, they don’t put on weight. Missing the growth schedule for thousands of birds for just one day stretches a farmer’s time to market and cash flow, something poultry producers want to avoid at all costs.

“Each building is wide open,” added Aungst. “So each area has a different heat loss profile depending on the location in the building. The goal is to keep the entire building at 93F (34C) at the beginning of every flock.”

To achieve that goal, his firm utilized an air handler system designed specifically for chicken houses. The system uses a centrifugal fan to circulate air through the mixer’s coil into the chicken house to maintain even temperature throughout the living area. Each building employs eight of the units suspended from the ceiling. A heating coil in each unit is supplied by a hot water circuit, which is regulated by its own pressure independent temperature control and system-balancing valve.

PRECISE TEMPERATURE CONTROL On warm days, to eliminate stratification the mixer pulls hot air from the ceiling level and expels it in a 360-degree circular flow just above the floor. On cold days, a boiler supplies hot water to the internal heat exchanger inside each air handler unit. The system uses an unusual fuel source − dried chicken waste − to fire the 1.5 million Btu boiler, which can handle 100 per cent of the heat load.

“The water flow to each coil is based on the heat load," explained Aungst. "At full load, the system supplies 180F water at 11 gallons per minute to each unit. But conditions seldom call for that much heat."

That is why Aungst is using eight pressure independent temMH24 | spring 2015

A heating coil in each air handler unit is supplied by a hot water circuit that is regulated by its own PICV.

perature control and system-balancing valves along the main piping circuit that runs near the peak of the roof in each building. One valve is used to control the water flow to one coil. The valve increases or reduces the flow of hot water supplied to the coil depending on whether the zone temperature sensors call for more or less heat. Because 100 per cent flow is usually not needed, a variable-frequency drive (VFD) incorporated into the circulating pump motor can reduce pump speed as flow is reduced, which cuts electricity consumption.

However, changing the flow also changes pressures, which creates problems for the system. Aungst determined that alternatives to the pressure independent control valve (PICV) design would not provide sufficient stability or controllability at low loads in this application. The control valve would have to do double duty: to provide water at the required flow rate

MODERN HYDRONICS

continued on pMH26 www.hpacmag.com

All Glycols Are NOT Created Equal CHEM-FROST Safe For All Systems

Including Aluminum and Solar

Premier Inhibitors Higher Temperature Rated Low Viscosity For more benefits ask your local wholesaler or visit chemfax.com

>> Renewables continued from pMH24

Temperature balancing is critical in the 45 x 500 ft. buildings.

The system is providing consistent temperatures across the 22 500 sq. ft. area.

to the air handler coil and to maintain that exact flow by eliminating the effects of pressure fluctuations on the valve as system loads change.

thermistors are all within one degree F,” concluded Aungst.

For Zimmerman, getting temperatures that consistent over an area about half the size of a football field is impressive.

“Some days require just a little heat. The chicks like an even temperature. So the valves open a little to provide heat without temperature swings. I’m very happy with how things are working,” said Zimmerman. <> - Bill boss

REMOTE MONITORING The PICVs and the variable speed drive pump work in harmony. Redundant pumps circulate the hot water to the circuits. The valve matches the flow to the exact load. And at lower loads, the pump reduces speed to save electricity. The pump only needs to produce the minimum required differential pressure for the valves to operate.

The valve actuator is controlled by a proportionalintegral-derivative (PID) loop in a programmable logic control (PLC) system that uses inputs from a thermistor located in each zone. The control network runs over Ethernet. Local control can be done on the PLC’s colour touch-screen. The system can also be monitored remotely from the comfort of Zimmerman’s home, combining convenience and reliability.

The biofuel system has been delivering. “Across a 22 500-square-foot floor area, the readouts on the eight

With over 40 years in the hydronic industry, Bill Boss is responsible for the sale of Danfoss’ hydronic heating and cooling controls, and oil burner components throughout North America. www.danfoss.com 1 A griculture and Agri-Food Canada, Government of Canada, Canada’s Poultry and Egg Industry Profile (2013-05-24) www.agr.gc.ca 2 A griculture and Agri-Food Canada, Government of Canada, All About Canada’s Red Meat Industry, (2013-05-24) www.agr.gc.ca 3 Statistics Canada, Government of Canada, Farm and Farm Operator Data (2015-01-08) www.statcan.gc.ca

Integrated design:

The next frontier for manufacturers, licensed architects, HVAC engineers/technicians and certified designers.

Professionals recognize the strong correlation between buildings, environment, and human health – but are your designers capable of collaborating to develop and market integrated products, systems, and programs?

On March 2, 2015, join veteran building and HVAC lecturer and long-time HPAC contributor, Robert Bean, R.E.T., P.L.(Eng.) in a live on-line registered thirty-three hour professional development program. You will have personal access to Robert during the 14-week course and you will receive over 2300 slides from Bean’s master library on indoor environmental quality, building science and hybrid radiant-based HVAC systems; plus you receive over a dozen Excel tools and numerous IEQ, architectural and HVAC design resources.

For more information and advance discounted registration, visit www.healthyheating.com.

MH26 | spring 2015

MODERN HYDRONICS

www.hpacmag.com

Coming Soon!

>> Circulators

Technology pumps out savings

V

ariable speed pumping has brought new levels of energy efficiency to the HVAC industry. While many larger buildings utilize system pumps operating on variable frequency drives (VFDs) with the guidance of pressure differential sensors, pumps that do not require external pressure sensors are an alternative. Before discussing the specifics behind this pump technology, a review of some basics behind system design, pump operation and selection is in order.

Let’s start with a 150-ton cooling system. The example shown in Figure 1 has five equal loads of 30 tons of cooling each, serviced by a chiller. Two-way control valves are used in four of the fan coils, but one of them is fitted with a three-way control valve that ensures a minimum amount of flow can remain in the system, even if all loads are satisfied.

When an engineer designs a hydronic system, he starts with the load calculations. He then selects the delta T for the system design, calculates the flow in GPM for both hot and chilled water, lays out the system, and calculates the pressure drop.

For the example in Figure 1, a 12F delta T was chosen, which equates to two gallons per minute (GPM) per ton for a total of 300 GPM. Next, we calculate the system pressure drop based

Figure 1 150-ton cooling system

Figure 2 System curve data table

MH28 | spring 2015

on the actual piping layout and total system resistance based on length and size of distribution piping, as well as the resistance of all other components in the system, including the heating/cooling source and terminal unit, valves and fittings.

In this example, it is approximately 53 feet of head.

Now that we have the design pressure drop and the design flow in GPM, we establish the design operating point.

SYSTEM CURVES As shown in Figure 2, a system curve data table can be generated using the formula shown. Basically, a system curve references the head pressure generated within the piping if nothing physically changes other than the flow (for example, head pressure generated in the system shown in Figure 1 with all valves wide open).

Some engineers may never actually draw the system curve but the system curve is implied in all designs. In most cases a system curve is generated by pump selection software. It is the interaction of the system curve with the pump curve that establishes the actual design operating point.

As valves in the system begin to close, the system curve responds to those changes as shown in Figure 3.

PERFORMANCE DATA Most pump manufacturers test each of their constant speed pump models on a test stand in order to generate the pump’s performance data and do this for each impeller size. An example of such a setup is shown in Figure 4.

Proper testing would typically require the following components: • Pressure gauges before and after the pump • Flow meter • Control valve/throttling device Figure 3 System curve responds to valve closure

MODERN HYDRONICS

www.hpacmag.com

Modern Hydronics

• Interconnecting pipe • Storage tanks • Input electrical power • Tachometer to confirm pump speed (not shown) • Torque cell to measure HP (not shown) • Data acquisition console (not shown) Sample test data is shown for a constant speed pump in Figure 5. Please note that far more test points would be recorded. For clarity purposes, only six test data points are shown in this example for a pump with an eight-inch impeller.

The same test is usually performed for each pump model with minimum and maximum impeller diameters, as well as three or four diameters in between.

Each constant speed pump can only operate on its pump performance curve. As the system curve changes based on added resistance in the system with zones shutting off, the flow would decrease. At this point, the pumps operating efficiency is reduced. In order to maintain highest operating efficiency, variable frequency drives (VFDs) can be added that can change the frequency provided to a pump’s motor and therefore alter the pump’s performance capacity.

Just as constant speed pump curves are generated, the same can be generated when operating the pump motors on different frequencies or speeds. As shown in Figure 6, using the same four-inch pump as was used earlier, new performance curves were generated using lower frequencies. This figure shows the performance curves overlaid with the mechanical example system curves.

Figure 4 Pump test stand

Please note that pumps should not be operated below 20Hz. At that point the minimum flow threshold is reached in order to lubricate the seals. Using VFDs allows a pump performance to be matched to the system without physically changing its impeller diameter and continually maintaining the pumps most optimal operating efficiency. This results in significant energy savings.

CONTROL CURVE The last remaining piece of the puzzle for this pump technology is the control curve as shown in Figure 7.

The control curve sets the direct relationship between the system curve and the pump curve for each frequency between the minimum and maximum frequency limits. This is the curve on which the VFD will self-regulate. pairing pump and drive Head, flow, power and speed information, as well as a resulting control curve, are programmed into the VFD. The pump and VFD are now paired and operate as a unit. A typical self-sensing pump VFD has received at least 50 data points. It can now operate at any flow and head within the collected data table simply by monitoring the power consumption and frequency matched to the recorded data.

Figure 8 shows the combined action that a drive can now take advantage of.

It continuously adjusts the speed of the pump and the performance curve to meet the dynamics changing in parallel with that of the system. The drive can provide a digital read-out of the changing dynamics at any time. The information may also Continued on pMH30 Figure 6 Performance and mechanical system curves

Figure 5 Sample test data – constant speed pump

Figure 7 Control curve

continued on pMH6 www.hpacmag.com

MODERN HYDRONICS

spring 2015

| MH29

>> Circulators Figure 8 Pump adjusted according to demand

“These pumps can be used for any application, including traditional operation with changing loads.”

be provided to a larger building or energy management system through a drive's building automation system (BAS).

As the demand in the system decreases, the pump rides to the left on the pump curve. The pump automatically responds by controlling the frequency provided to the motor and keeps the pump on the control curve. As the system demand increases, the opposite will occur and the frequency provided will increase, keeping with the dynamics of the system.

These pumps can be used for any application, including traditional operation with changing loads (as discussed previously), but also to provide a match for any constant volume or constant pressure applications, as highlighted in Figures 9 and 10.

While drives with this technology can be provided loose, several pump manufacturers offer these pumps with the drives directly mounted, which provides some labour savings on the installation side as well. <> - Mike Miller

Figure 9 Control curve for a constant pressure application

(such as pressure booster applications)

Figure 10 Control curve for a constant flow application (such as process applications)

Mike Miller is chair of the Canadian Hydronics Council (CHC) and director of commercial sales, Canada with Taco Canada Ltd. He can be reached at hydronicsmike@taco-hvac.com. See Mike at Modern Hydronics-Summit 2015 on September 10 in Toronto (see pMH10 for more information).

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