n Controls

Complete building control

Honeywell, Atlanta, Georgia, launches several new products during the recent AHR Expo 2023. The Honeywell Optimizer Suite consists of a variable air volume (VAV) controller, a unitary controller and an advanced plant controller to help any existing building system. The Honeywell Remote Building Manager allows owners and tenants to monitor energy use, reduce operational costs, and manage their building’s systems 24/7 from anywhere. The TR50 Indoor Air Quality Sensor provides continuous IAQ monitoring and visual confirmation of air quality. Lastly, the Honeywell Buildings Sustainability Manager is an autonomous controls platform with a suite of applications that help customers meet carbon reduction goals.

Honeywell www.honeywell.com

Plug-and-play zone solution

Airzone, Atlanta, Georgia, announces the launch of Easyzone in North America, a plug-and-play, all-in-one zoning solution for concealed inverter and VRF HVAC units. Easyzone can regulate temperature and airflow capacity in up to six independent zones. The Easyzone ships as a pre-wired kit, including a thermally insulated motorized plenum, control board and plenum neck. Easyzone is available with either six-inch or eight-inch dampers.

Airzone www.airzonecontrol.com

CO2 monitoring

Network Thermostat, Grapevine, Texas, introduces its latest flagship model, the NetX X7C thermostat, which features CO2 monitoring and control. The NetX X7C features an internal CO2 sensor and does not require field calibration for five years. The thermostat also includes an internal expansion port for the NTMOD-ULE, creating the ability to use Dect ULE wireless sensors. Daily commercial scheduling, independent event scheduling, keypad lockout, and demand response control are included in all X7 thermostats.

Network Thermostat www.networkthermostat.com

Mini split/VRF controller

Fujitsu, West Fairfield, New Jersey, announces the Kagami controller, its new mini-split and VRF controller. The controller offers touchscreen control of Airstage H, J and V-Series systems. It features a backlit touch panel that displays room temperature when activated, along with the current time. Kagami can be customized with logos from hotels or other properties. It allows up to 16 individual Fujitsu indoor units to be simultaneously controlled from a single unit.

Fujitsu www.FujitsuGeneral.com

Single stage heating thermostat

Watts Water, Burlington, Ont, debuts its new smart and connected W561 thermostat to market. The Wi-Fi connected thermostat offers temperature control of a single-stage heating system and can be controlled remotely. The W561 features a seven-day, four-event programmable schedule and an early start feature that automatically heats up a room by the scheduled time.

Watts Water www.watts.com

Single-family controls

Uponor, Mississauga, Ont, debuts the Smatrix Pulse, a new multi-zone wireless control for radiant and air-side comfort in single-family residences. The Smatrix Pulse allows users wireless control of their radiant floor heating and forcedair heating and cooling systems. The controller can accurately measure air, surface, and floor temperatures in each zone with embedded operative sensors in the thermostats along with optional slab sensors. It can be connected to a smart home device for voice-activation control. A single controller configures up to six thermostats, eight actuators, and one remote relay using local networks. Adding an expansion module adds six more thermostats, eight more actuators, and one more remote relay to the controller. For larger residences, a controller with an antenna can connect up to four controllers and expansion modules for a total of 48 zones.

Uponor www.uponor.com

Environment controller

Johnson Controls, Milwaukee, Wisconsin, announces the release of the Metasys CCM09090 critical environment controller. The CCM09090 is a room-level controller that controls temperature, humidity and air handlers for spaces like complex labs with multiple fume hoods and healthcare facilities. The controller also features a high-definition capacitive touchscreen display and 18 communication points to equip input/output flexibility.

Johnson Controls www.johnsoncontrols

By Greg Scrivener

As air conditioning season gets underway, it’s a good time to review how to measure superheat and subcooling. These two measurements are two of the most important parameters needed to understand what’s happening in an air conditioning system when either charging or troubleshooting. In simple terms, and in the context of air conditioning, superheat is above the boiling point of a substance – in our case, refrigerant.

The function of an evaporator is to boil liquid refrigerant by absorbing heat from the warmer air going over the coil. This is the same concept as a pot of water absorbing heat from the element on your stove to boil, except that in the air conditioning coil, it’s happening a lot colder, around 40 F. Once the refrigerant has completely boiled and is 100 per cent vapour, it is still colder than the air going over the coil; this means that any more heat we add to it will start to increase the temperature of the refrigerant. This increase in temperature is what we call superheat.

It’s very difficult to measure the actual temperature of the coil since it’s inside ductwork with air moving over it; instead, we use the relationship between pressure and temperature to determine the temperature of the coil. A pure fluid boils at a constant temperature for a given pressure. For example, water boils at 100 C at sea level, but at the top of Mount Everest, it boils at 68 C because the air pressure is so much lower. Similarly at sea level, R410A boils at -51 C and on the top of Mount Everest it would boil at -71 C. Explained in the opposite way, as we increase the pressure on a fluid, the boiling temperature goes up. It turns out that for R410A, if we measured a pressure of 118.4 psig in our coil, then the temperature at the evaporator coil would be 40 F.

Figure 1 shows this relationship on a screenshot from a refrigerant pressuretemperature (PT) app and schematically with a pressure measured on the suction line determining the temperature in the evaporator coil.

Measuring on the suction line

Superheat is heat that is added above the boiling temperature. On split systems, this is often measured on the suction line near the compressor, as shown in Figure 2. In this case, you can see that the temperature in the coil is 40 F and the temperature on the suction line is 55 F. The superheat is the difference between these temperatures, which would be 15 F. There are two potential pitfalls with these measurements to pay very close attention to suction line pressure drop and suction line temperature gain. Consider a suction line that has a pressure drop of five psig. In this case, you would see what is shown in Figure 3. The pressure at the condensing unit would indicate 113.4 psig, which would lead you to believe the evaporator temperature is 38 F. With the same temperature measurement of 55 F as the previous example, the superheat would now seem to be 17 F

Similarly, there is a potential problem with measuring the temperature at the condensing unit. Since the suction line is most often colder than the ambient air temperature around it, the refrigerant gets additional superheat as it travels from the evaporator to the compressor. This temperature rise is particularly noticeable if the suction line is long or poorly insulated. Figure 4 shows how this could cause an overestimation of superheat. In this case, the actual evaporator superheat is 5 F and there is 10 F of suction line superheat.

The distinction between evaporator superheat and suction line superheat — often called useful and non-useful superheat, respectively — may or not be important to you. If you are just checking the superheat to ensure that the compressor is protected from liquid flood-back, a degree or two may not matter at all. However, if you are setting up a new air conditioner or troubleshooting, these two potential measurement errors can have significant consequences. One of the reasons these concepts are important to grasp is that many types of electronic gauges do all of these calculations for you. This can lead to a reliance on the information the gauges provide without a solid understanding of

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Canadian refillable cylinders available