23 minute read
Evaporator pressure regulators
When energized, a solenoid causes the valve to close, which allows hot gas to flow in the opposite direction up the suction line.
By controlling the pressure in the evaporator, the technician is ultimately able to control the temperature in the evaporator. By Greg Scrivener
Evaporator pressure regulators are pressure regulators used in the suction line, leaving an evaporator to control the pressure. This means that they are inlet pressure regulators. They take the pressure input from the inlet piping and open/ close the valve to maintain a set pressure. The valve outlet pressure always has to be lower than the inlet pressure otherwise there will be no refrigerant flow. There are a couple of reasons why you may want to control the suction pressure in an evaporator.
In commercial refrigeration, these valves are most commonly referred to as evaporator pressure regulator (EPR) valves and occasionally as ORITs (based on a common model nomenclature). In industrial refrigeration, they are usually only referred to as suction pressure regulators or simply suction regulators.
Recall, of course, that by controlling the pressure in the evaporator, we are controlling the temperature in that evaporator. This type of control may be desirable or necessary for several reasons, including preventing ice formation on an air evaporator and minimizing defrost, preventing freezing in a chiller, or controlling the temperature of the evaporator to minimize product impact.
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Figure 1: Here is an example of a basic refrigeration system with no EPR valve.
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First, let’s take a look at the simple refrigeration system in Figure 1. In this system, the evaporator pressure, and therefore the temperature, is only a factor of the refrigeration system balance. If there is a decrease in load at the evaporator, less refrigerant will boil. The compressor has to move the same amount of refrigerant as the evaporator boils for the pressure to stay constant. That way if the evaporator reduces how much refrigerant boils, the pressure will drop until the flow balances. This happens because as the refrigerant pressure falls its density also decreases. Since the compressors we use are constant volume pumps, a lower density means less mass is moved through the compression each stroke or cycle. The condenser will reject the heat that was absorbed in the evaporator combined with the heat that was added during the compression.
Special cases
In many refrigeration systems, the basic system described above works perfectly fine because as soon as there isn’t a load at the evaporator, the temperature is low enough that the system shuts down (or that evaporator shuts down at least). However, in some cases, this decrease in pressure and temperature is not acceptable. Consider an application with sensitive products like flowers. In some of these applications, we want to make sure that the air temperature off of the evaporator never decreases below a certain point. In order to do that, we can add a pressure regulator in the suction line, as shown in Figure 2.
This pressure regulator functions by adjusting to match the inlet pressure setpoint. Mechanical valves use a spring and bellows so that when the pressure drops below the setpoint, the valve is completely closed. As the pressure increases above the setpoint, the valve opens, depending on its sensitivity, until it is fully open.
Using R507 as an example, if we set our EPR from Figure 2 at 76 PSIG, we would be assured that the evaporator coil never reached a temperature below 32 F. In fact, it would be at almost exactly 32 F whenever it was running, and this provides very consistent air temperature leaving the coil. Consider a water chiller as opposed to an air coil in this application. The evaporator temperature mustn’t go low enough to freeze the water. Water chillers also often must operate in a very large range of capacities and have compressors with unloaders and other capacity control. This means they are at fairly high risk of being in a situation where there is an imbalance between the compressor and evaporator that causes the pressure to decrease.
Frost levels
Similarly, it is usually desirable to reduce the amount of frost that builds up on an evaporator. In the case of an air conditioner that isn’t designed to handle any frost, an EPR can be used to maintain adequate suction pressure to prevent frost from forming at all. Employing an EPR in this way for air conditioning is not typical since most air conditioning systems can operate fine without this extra control but they are used on some specialty air conditioners. It is more common to see EPRs used on a system with multiple evaporators operating at different temperatures, as shown in Figure 3. It is possible to refrigerate a space
Figure 2: Here is a basic refrigeration system with an EPR valve.
Strategically
employing EPR
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to 35 F using a -20 F coil. However, the amount of frost that collects on a coil increases with a decrease in the coil temperature, and coincidently, this also results in low humidity in the space since more water is removed. In order to prevent this, an EPR can be used to maintain a higher temperature in the coil.
Drawbacks
Other than the obvious fact that using an EPR increases the cost of the system, there are two main drawbacks to using an EPR. The first is that there is always an energy penalty when you use a pressure regulator on a suction line. At full load, you have introduced a pressure drop that wouldn’t otherwise exist in the line, and if you recall the rule of thumb, for each 1 F SST equivalent in pressure drop, there is about a two per cent energy penalty. For our R507 example, that means if this regulator introduced a 1.5 psi pressure drop (which it likely would), there would be a two per cent energy penalty. The other drawback is a bit more subtle and applies mainly to systems with high peak loads. It is sometimes desirable to float suction pressures down to increase the refrigerated capacity of the evaporator. This can be done in modern refrigeration controls by decreasing suction pressure set points, which allows more compression (either with capacity control on a single compressor or by adding compressors). This option is not possible with standard EPR valves.
EPR valves are available with many options. Probably the most common is a combination EPR/suction stop valve that is used for hot gas defrost. These valves include a solenoid that, when energized, causes the valve to close so that hot gas can flow in the opposite direction up the suction line. Hot gas valve groups will be a topic of a future article since there is not enough time to go into detail here.
Strategically employing EPR valves can improve the operation of complex refrigeration systems; while using EPR valves on every circuit is common practice in both industrial and commercial applications, there is a substantial energy penalty that ought to be considered. There are additional complications when using these types of valves with pumped liquid; things can become even more challenging when electronic suction regulators are used since they behave differently in power outages. As is often the case, there is a delicate balance between operation and energy and lots of things to consider. :
Figure 3: An EPR can be used to maintain one evaporator at a higher temperature. An EPR valve doesn’t always need a suction stop solenoid.
Greg Scrivener is the lead refrigeration engineer and a partner at Laporte Consultants, Calgary, and works throughout Canada and the U.S. He is a professional engineer and journeyperson refrigeration mechanic. He can be reached at GScrivener@laporteconsultants.com.
After three decades, Marie Li-Ying will be retiring and will be taking a welldeserved break.
After 30 years of working within the refrigeration sector, Marie Li-Ying announces her retirement from Honeywell. By Leah Den Hartogh
“It’s been quite a ride,” stated Marie Li-Ying, business manager of fluorine products at Honeywell. “I’ve enjoyed every minute of it. You’ve got the highs and lows, and interestingly, being with the same company for such a long period of time, I’ve been able to see how business has changed over the years.” Li-Ying has been with Honeywell for 30 years as she announces her retirement.
A long-time volunteer within the HVAC/R industry, Li-Ying has worked closely with HRAI for many years.
Over her career, she has put plenty of time and effort into volunteering at associations, including her work at Refrigerant Management Canada (RMC). It was her work with this association, managed by the Heating, Refrigeration, and Air Conditioning Institute of Canada (HRAI), that she received the Warren Heeley Environmental Achievement Award in 2021. She was instrumental in the creation of RMC, which is essentially an environmentally responsible program. It manages the disposal of Canada ’ s stocks of surplus halocarbon refrigerants for the refrigeration and air conditioning industries.
“You are well deserving of this award. On behalf of HRAI, we wish to thank you
for the countless hours that you have spent volunteering your time and for helping Refrigerant Management Canada with our simple, easy to use, industry-wide collection program for the final disposition of the end of use of refrigerants in a safe manner,” said Caroline Czajko, director of environmental services and the manufacturing division at HRAI, in a video awarding the honour to LiYing.
According to Li-Ying, Refrigerant Management Canada is the first of its kind, worldwide — “Other companies, other countries have looked at it and it’s become something to be proud of as Canadians.” She is currently the past chair of the board of directors and previously was the treasurer for RMC.
Additionally, the work she has been a part of during her tenure at Honeywell has been something she is quite proud of, especially the amount of money the company has invested in research and development. “Overall, when you look at what the company has done with this new product, the HFO or hydrofluoro-olefin, it’s equivalent to like 688 million barrels of oil that you’re removing from the atmosphere.”
She initially joined Honeywell in the midst of the phasing out of CFCs. “It was quite hectic
initially and then it would slow down,” said Li-Ying. “It makes you feel good when you’re part of an industry that’s looking ahead at the environment in general. The sustainability of the product and what we can do to make sure that the carbon footprint that we’re leaving is responsible as well.”
Pay-it-forward
Being able to pay-it-forward is something that Li-Ying has tried to embody in both her personal and professional life. During our conversation, she remained quite humble regarding the work she has done for the industry over the past three decades.
It’s to no surprise that she said that she hadn’t quite accomplished all that she could have in her career. But she did remark that very few could probably say that they have done everything that they’ve set out to do. “That goes part of always learning and wanting to do more,” she said. “I’m always surprised and humbled that anyone would ask me to be a role model. ”
Growing up in a Chinese family, she said that oftentimes the males of the family took on the more dominant role, but that her grandmother was unique and ahead of her time. “Even as a female, you need to do the best you can and support yourself. You’re not supposed to be dependent on anyone just because you’re female,” said Li-Ying. “My mom and my grandmother were very great role models.” When she first started in the industry, she often found herself being the only woman in a lot of her roles.
Time-off
It hasn’t always been easy juggling a healthy work-life balance, especially over the pandemic, but she is looking forward to some “me time. ” She and her husband are thinking about doing some renovations to their home. There has also been some planning to do some travel. “We love to see exotic places. We’ve done a fair bit of Europe, but we haven’t done much of Asia. So, we’re looking forward to doing more travelling. ” :
People The
Navac appoints Bryan Schwartz to the newly created position of national training manager. He will be responsible for training development programs, in-person and Bryan remote instruction, organizing Schwartz education-relation projects and opportunities, and managing other Navac training personnel. Schwartz initially joined the Navac team in 2020, and prior to his time with Navac, he was senior national training manager for LG Electronics.
Centrotherm welcomes Eckhard Hilscher as the new regional sales manager, responsible for the east coast. He comes to Centrotherm after nearly two decades with Hart & Cooley, where he previously served as national accounts manager of the wholesale division.
Eckhard Hilscher
Adam Hedden Bryan Jones Evan Cikaluk
Nick Bérubé
Pierre Huneault
Equipco has announced several new associate partners to its team. Adam Hedden, Bryan Jones, Evan Cikaluk, Nick Bérubé, and Pierre Huneault will take on the role of associate partners. “As we celebrate 40 years in business this month, we also are looking ahead and planning for the next 40 years! Please help us congratulate Nick, Adam, Pierre, Evan, and Bryan for being selected as that “next step” and receiving the title of associate partner,” shared Equipco on its social media.
The Companies
Sauermann Americas announces the appointment of Wildon Sales and Marketing Inc. as its Canadian territory representative for combustion products. As the Canadian territory representative, Wildon’s team is set to develop new partnerships and contribute to Sauermann America’s combustion product sales and business strategies in Canada.
Wolseley Canada opens a new branch in West Kelowna. Located at 1315 Industrial Road, the West Kelowna branch is a 17,000 sq. ft. facility that offers a full range of Wolseley Canada’s roster of plumbing and fire protection products, with HVAC products to be added over time. A formal grand opening was held on Nov. 17, while the new branch has already opened.
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Patent Pending
A recession could be coming down the pipeline; set up a preventative maintenance plan for your business now. By Ron Coleman
Interest rates have skyrocketed in recent months. Not only that, but the forecast for 2023 showcases further increases. The good news is that Canada created 108,300 full-time jobs in October 2022.
The bad news is that 42 per cent of small businesses didn’t pay all of their rent in October, and September was almost as bad, according to an Alignable Research Center poll published in October.
A recent study by Statistics Canada shows that the country has a very low unemployment rate and that labour costs are increasing dramatically. These costs get passed on to the consumers and push inflation higher. The government counters this by pushing up interest rates, which in turn causes increases in wages, and so on.
The balance the government is aiming to achieve is to tame inflation without causing a recession. That is an extremely difficult task. We need to ensure that, while we hope for the best, we must plan for the worst.
The beginning of 2020 was very rosy. Nobody had any idea what the next two years were going to bring. Without financial aid from the government, I am sure many would not still be in business. It is highly unlikely that the government is going to bail us out in 2023. We are on our own and must plan accordingly. Running your HVAC or plumbing business is akin to the feds aiming to balance inflation and recession. Difficult but not impossible.
Find the stability
Let’s explore interest rates first. Normally I advocate businesses and homeowners to go with variable interest rates. But, now that we need a better sense of stability, I would recommend that you lock in as much of your debt as possible for at least three years.
If you are going to borrow money, make sure that it will generate a positive cash flow. Buying new equipment and vehicles is an ongoing investment we make in our businesses. The cost of vehicles is at an alltime high, and operating costs are also rising rapidly. Explore not only the capital cost of a vehicle but the operating costs. We all know that electric vehicles are the way to go. So, buying a gas-powered vehicle now, which you will expect to use for at least five years, might not be the best decision. The availability of electric vehicles will be a lot better in two years. Maybe buy a used vehicle and keep it for two to three years. This also reduces your investment and interest charges and will reduce your operating costs when you get the electric vehicle. Only buy what you really need.
If your need is short-term, then do a shortterm rental or lease. Do an internet search or check with your association as there are companies that specialize in short-term rentals and leases. Can you rent the equipment you need? Can you defer the investment?
Working capital
Apart from fixed (capital) assets, we also use lines of credit for financing our operations. That’s called working capital. There are several reasons we need working capital in our business. First, look at your current assets. The largest categories are likely accounts receivable and inventory.
Reduce your accounts receivable by being more persistent in your collections and by getting deposits. If you are doing new construction, monitor your holdbacks. Make sure you invoice all work at the earliest date possible.
There are two sides to inventory, which we covered this in a previous article. The balance is between carrying enough to service your customers in a timely manner and maintaining the lowest level to lower borrowing costs.
We need to have a contingency plan in case of a recession. We had enough surprises with COVID-19, we can’t afford anymore.
If you look at your salaries (that excludes wages in direct labour), you will see that
salaries represent approximately 50 per cent of your overhead. You will also realize that most of your overhead is fixed or very close to fixed. You can make some savings on cost elements such as advertising as long as it doesn’t reduce your income. You do need to look at the cost/benefit of overhead decisions.
The real focus needs to be on your overhead labour. As the owner, maybe you can reduce your salary temporarily. It’s your company, so you’re not really losing anything. You are protecting your investment. Have a strategy for having estimators, project managers and other staff with trade backgrounds being pushed down to direct cost as superintendents. You will retain your good people, reduce your overhead, and likely increase production as these are often people that are very efficient on the job front. Superintendents become foremen, foremen become journeymen and lay off the least productive journeymen.
I know we hate to lay off our top people, but if our numbers are not there, we can’t afford the false economy of hoping things will turn around. Hope is not a strategy.
Cost cutting methods
We also need to look at cost-cutting measures in the field and the shop. Start by looking at areas that can be automated. I hope none of you are still using traditional timesheets. Technology has moved so far in recent years that many steps in our businesses are being automated. Your competitors are doing this, and you are getting left behind if you are not investing in technology.
There are numerous government incentive programs to streamline your technology. We have covered those in a previous article, as well as explored areas around efficiency.
Revisit your estimated costs and your charge-out rates. I recently did a workshop on labour rates and none of the contractors were including a warranty as a cost of labour. MCA Canada recommends that labour costs should be increased by three per cent to cover potential warranty issues.
There is no downside in preparing for a recession. There are several upsides. The first one is it will force you to be more profitable. That will reduce your need for borrowing and build up your cash reserves to protect you in case of a recession. This will increase the value of your business. You will also feel more secure and less stressed out and know how to protect your key employees. By streamlining your investment in equipment and vehicles, you will reduce costs.
I am sure all you service contractors constantly tell your customers the importance of preventative maintenance. No heat and burst pipes are never fun. They cost more to fix and are very disruptive. Follow the advice you give to your customers and start your preventative maintenance plan now. :
Ronald Coleman is a Vancouver-based accountant, management con sultant, author and educator spe cializing in the construction industry. He can be reached by e-mail at
ronald@ronaldcoleman.ca.
Best of KBIS accepting entries for 2023 contest
Each year, the Kitchen and Bath Industry Show recognizes the newest innovative products to the plumbing sector.
It’ s that time of year again. The National Kitchen and Bath Association (NKBA) is hosting its annual Kitchen and Bath Industry Show (KBIS) from Jan. 31 to Feb. 2 at the Las Vegas Convention Center in Las Vegas, Nevada.
In addition, entries for the show’s 2023 Best of KBIS Awards are now being accepted. The contest recognizes new innovations in the kitchen and bath industries, with a formal ceremony taking place at the KBIS NeXT Stage on Feb. 1.
“The Best of KBIS program celebrates new product innovation among the kitchen and bath industry and assists in elevating the KBIS platform,” said Suzie Williford, executive vice president and chief strategy officer of NKBA. “This program showcases year-after-year, the “best-of-the-best” in our industry. I can’t wait to see what new innovations come to Vegas this year!”
The Best of KBIS is broken down into different categories, including best of show, kitchen (gold and silver), bath (gold and silver), connected home technology, and the impact award (judge's choice). Submissions will be accepted until Dec. 2.
To be eligible for the contest, all products must have been introduced after Feb. 1, 2022. To enter, exhibiting manufacturers must complete a submission form and submit at least two high-resolution images. Products may be entered in multiple categories but require an individual entry form and submission fee for each category.
A judging committee, comprised of five design professionals, will narrow the entries to 50 finalists, which will be judged onsite at the show. Each finalist will have five minutes to present their product to the judges during an in-booth visit. The judges will be announced at a later date.
INDEXto ADVERTISERS
Bradford White .....................................4 CB Supplies .........................................16 Delta ...................................................47 Equipco .............................................38 Fernox ................................................26 Flocor .................................................10 Fujitsu .................................................32 Giant .................................................11 Haier ..................................................22 Honeywell ..........................................34 ICP .....................................................27 Intertek ..............................................23 Lync .....................................................2 Lyncar ................................................42 Master Group ....................................20 Napoleon ...........................................18 Navien .................................................9 Rinnai ..................................................6 RWC ..................................................48 Thermo Manufacturing ......................33 Triangle Tube .....................................30 Watco ................................................43 Wolseley ............................................36 Woodford ..........................................24 Ziehl-Abegg .......................................14
Calendar
Nov. 30 – Dec. 2, 2022,
The Buildings Show,
Metro Toronto Convention Centre, South, Toronto, Ont. For more information, please visit www.informaconnect.com/ the-buildings-show.
Jan. 31 – Feb. 2, 2023,
NKBA/KBIS:
Las Vegas Convention Center, Las Vegas, Nevada. For more information, please visit www.kbis.com.
Feb. 6 – 9, 2023:
AHR Expo 2023,
Georgia World Congress Center, Atlanta, Georgia. For more information, please visit www.ahrexpo.com.
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HOW COPPER WORKS
Research indicates that copper has several modes of action against bacteria. One such mode of action is ion exchange, which researchers believe works like this1:
1.Copper surfaces contain copper ions that are recognized by bacteria as an essential nutrient.
2.The copper ions enter the bacteria providing a lethal dose that interferes with normal cell function and membrane integrity.
3.Cell respiration/metabolism is impeded and DNA damage may occur. The bacteria can no longer consume food or reproduce, and dies.
Clean and sanitize according to standard practice. Healthcare facilities must maintain the product in accordance with infection control guidelines. The use of this surface is a supplement to and not a substitute for standard infection control practices; users must continue to follow all current infection control practices, including those practices related to cleaning and disinfection of environmental surfaces. This surface has been shown to reduce microbial contamination, but does not necessarily prevent cross contamination. 1 Vincent, M., R.E. Duval, P. Hartemann, and M. Engels-Deutsch et al, Contact killing and antimicrobial properties of copper, Journal of Applied Microbiology, December 27, 2017; 124:1032—1046. Source of graphics: Drs. Grass, Keevil, Rensing, and Soliaz courtesy of the Copper Development Association
CuVerro® and CuVerro ShieldTM are registered trademarks of Wieland North America, Inc. and are used with permission. © 2022 Masco Canada Limited
