Condensing units may well be the “face” of the air conditioning industry. If you ask typical consumers about air conditioning, it’s likely they would point you to the sharp-looking unit next to their house. But, condensing units are also much more than a pretty face — they’re one of the key economic drivers in the HVAC industry.

According to Tom Archer, product manager, Carrier Corp., variable-speed or inverter-based equipment is an emerging trend in residential ducted condensing air conditioners and heat pumps. Multistage condensing units and variable-speed ductless condensing units have existed for several years, yet, only recently have the advantages of variable-speed compression been applied to ducted equipment.

“Variable-speed compression offers the ability to better match the equipment performance with the needs of a variable load, as in residential homes,” Archer said. “A variable-speed condensing unit offers advantages for several applications, including heat pumps where, as the ambient temperature declines, the compressor speed can be increased to pull more heat out of the ambient air, or in high humidity, where the variable-speed compressor can improve the humidity control of the system by reducing its operating speed.”

While equipment is typically sized for the design load, it frequently operates at less than full load, said Archer, adding that 70-80 percent is typical for the majority of its operating cycle. Variable-speed equipment can reduce the compressor operating speed to more closely match the load condition. This increases efficiency by drawing less power at lower operating speeds.

In contrast, a single-stage condensing unit operates at a fixed speed. It cannot speed up for improved performance nor can it reduce its speed when the operating parameters are at part-load conditions.

Variable-speed condensing units also have enabled manufacturers to make dramatic reductions in the overall size and weight of condensing units. Some recent models are approximately 50 percent the size of a traditional single-speed, two-stage condensing unit with the same efficiency rating.

Archer concluded that communicating HVAC systems are becoming increasingly prevalent. In these systems, each component can communicate with the others beyond a simple 24-vac on-off signal. This allows the system to self-configure, share optimal operating information, and communicate diagnostic information.


Farooq Mohammad, director, product management, air conditioning division, Rheem Mfg. Co., said the general trend in the industry continues to be higher efficiencies. How those higher efficiencies are achieved is changing, however, particularly in the U.S.

According to Mohammad, U.S. manufacturers traditionally used the air side of the system to gain higher efficiencies. They’ve increased the size of the heat exchanger surfaces and moved to more efficient fans and motors. This is an effective way to increase efficiencies when space isn’t a constraint. In the space-restricted Asian market — Japan, in particular — the concentration since the 1980s has been on managing refrigerant flow.

“We’ve kind of come to a crossroads here in that the size of the equipment continues to increase, and the cost of materials goes up,” Mohammad said. “So, we’re increasingly turning our focus to the refrigerant side of the system and going with variable-speed compressors and drives to increase efficiency.

“It’s a little bit more sophisticated in terms of technology and controls, but it makes the overall system cost a little more bearable and allows some higher efficiencies to be reached,” he added. “On the air side, we were beginning to run into the laws of diminishing returns.”

Mohammad said contractors will see the largest difference in the areas of education and training, adding, Rheem has a robust training program for all the distributors who are going to carry the company’s premium inverter products, as well as for service managers and contractors.

“There’s more complexity on the premium, high-efficiency equipment,” he said. “It won’t add a whole lot of time to the installation, but, when it comes to servicing the equipment, contractors and technicians are going to need to understand the technology and the different signals and diagnostics the equipment is providing them. Training is going to be a very important part of implementing these high-end units.”

Looking down the road, Mohammad said he expects consumer demand to drive more high-end products. “Our industry has never been a ‘bell curve’ type of industry,” he said. “Most industries sell a small number of minimum-feature products, the bulk of sales come from the middle, and a small amount occurs at the high-end, premium side of the curve. Traditionally, the bulk of our industry has been built on the minimum-feature, minimum-efficiency type of products, then there’s a presence in the middle, and very little at the high end.

“I think that’s going to change five years down the road because society is becoming more informed and tech-savvy,” Mohammad said.

“Products are becoming more sophisticated, whether it’s smartphones, TVs, appliances, or automobiles. I think there’s a general expectation that people want to be able to control and communicate with their appliances and electronics. It’s just a general paradigm shift in our society, and everything is moving at breakneck speed. So, we’ll see some of that impact in our industry, as well. The increased use of electronics is kind of a megatrend in society; our industry is just catching up with it.”


Tom Brittain, product manager, air conditioners and heat pumps, Lennox Intl. Inc., said, in order to understand trends in the HVAC industry, one must look at what’s happening on the regulatory side related to minimum efficiencies and what the market is demanding related to high-efficiency systems. For example, condensing units produced in 2015 and beyond will need to meet U.S. Department of Energy (DOE) regional efficiency standards.

“It’s important dealers understand the minimum efficiencies required for residential installations in their areas,” Brittain said. “Dealers also need to understand the record-keeping requirements for residential equipment installations.”

For split-system air conditioners in the U.S., 14 SEER is now the minimum for the South and Southwest, while 13 SEER remains the standard in the North. For split-system heat pumps, the new minimum national standard requires 14 SEER and 8.2 HSPF. Brittain said consumers ultimately will benefit from the push toward higher-efficiency systems and reassured dealers that Lennox will continue to ensure the right products are in the right locations to help them remain compliant with the 2015 standards.

Like Archer and Mohammad, Brittain said manufacturers are using a variety of new technologies, such as variable-speed and capacity, to deliver better comfort and connectivity. “Instead of having one or two stages, manufacturers are delivering multistage and variable-capacity condensers,” Brittain said. “The idea is to provide the exact amount of cooling and humidity control required to meet the demands of a home and, therefore, a customized level of comfort on any given day. Look for that type of technology to become more prevalent in the coming years.”

He also agreed that communication capability will continue to expand with condensing units.

“Increased connectivity known as the Internet of Things [IoT] will continue to make an impact in the HVAC industry,” Brittain said.

“We’ve seen it in the proliferation of connected devices and in the area of home automation. The way in which consumers interact with their HVAC equipment will continue to evolve. In a very short time, we’ve gone from thermostats that were adjusted manually to programmable thermostats to Wi-Fi-enabled thermostats that allow homeowners to adjust their home temperatures from anywhere in the world.”

He pointed out that smart thermostats now can adjust a system’s fan speed based on local allergy-inducing conditions to provide better filtration and eliminate airborne particles, pollen, and ozone. Geofencing technology, which is tied to a homeowner’s mobile phone, will alert the HVAC system to turn the temperature up or down automatically based on the homeowner’s proximity to the house.

“It’s an exciting time for the industry,” Brittain said.


Matt Lattanzi, director of product management, Nortek Global HVAC (formerly Nordyne), also sees consumers looking for more flexibility, control, and lower energy bills, which is leading to more advancements in communicating technologies.

“The convenience of monitoring energy usage and the flexibility of remotely changing system settings are rapidly gaining prominence in the industry,”
he said.

Contractors can also expect to see more condensing units that communicate with the indoor system and the thermostat. Heating and cooling equipment will be a major component of the smart home.

“Another trend in air conditioning is new designs using inverter technology. Inverters allow the air conditioner to modulate capacity, so they are extremely efficient and quiet,” Lattanzi said. “These high-end systems are becoming more contractor- and installer-friendly as the industry gains experience with this technology.”

Contractors also are going to see a growing number of split systems with microchannel condensing coils. The benefits of this all-aluminum coil technology, according to Lattanzi, include reduced weight, up to 50 percent less refrigerant charge, smaller footprints, less susceptibility to transportation damage, and greater corrosion resistance.

Lattani concluded by noting that more regulation is imminent in the industry. “We are just getting into the 2015 regional standards, and the next rulemaking for central air conditioners and heat pumps has already begun” he said.

“In addition, unitary large equipment (light commercial) is also going through another rulemaking that will establish a new regulated metric. IEER, or part-load efficiency, will be the dominant metric in this market segment as we move forward.”


Roxanne Scott, condensing unit product manager, North America, Tecumseh Products Co., said that, although viable alternative refrigerants are being approved by the U.S. Environmental Protection Agency’s (EPA’s) Significant New Alternatives Policy (SNAP) program, OEMs still require testing to determine how they impact overall performance and efficiency of the system, including the condensing units. With any condensing unit, the compressor and coil selections have to take into account which refrigerant is used.

“With unknown factors, such as which refrigerant the major players in the industry will move to, and whether the EPA will increase flammable charge limitations or extend the time for delisting R-404A/R-507A and R-134a, designing an unfavorable refrigerant that no one else intends on using could be a deal breaker,” Scott said.

“The industry, as a whole, is trying to determine the overall direction by diligently testing and identifying promising alternative refrigerants under programs like the Air-Conditioning, Heating, and Refrigeration Institute’s (AHRI’s) Low-GWP Alternative Refrigerants Evaluation Program to reduce duplicative work and decide the
best alternatives.

“Until a definitive direction is provided, engineers are scrambling to be prepared to move in the direction the DOE requires for efficiency without ultimately knowing which refrigerant will be the one the market demands,” she added.

According to Scott, design trends for condensing units will lean toward selecting the most energy-efficient components while attempting to remain within the same footprint or smaller. Footprint and overall condensing unit size are strictly limited due to their installation within the end-user’s cabinet or case. Customer connection points and devices such as dual- or low-pressure controls typically need to remain in the same locations for ease of access and installation purposes; however, this has a bit more flexibility than the overall footprint and size of the unit.

“Unfortunately, increased capacity typically also means an increased refrigerant charge, so, modifications will be needed to reduce the charge size of an R-290 condensing unit to remain below the EPA’s 150-g charge limitation,” Scott noted.

“Condensing units can be redesigned to achieve this by paying attention to the internal refrigerant volume of coils and the liquid receiver and by using different evaporator tube sizes and/or changes to capillary tubes. Flammable refrigerants being used may also mean other components within a condensing unit will have to be suitable for flammable use. Other component changes need to be addressed to account for pressure differences — a high-pressure switch intended to be used on an R-290 condensing unit may require a different psi setting rather than that used for R-134a today.”

Depending on the application in which the condensing unit is used, other technologies may be integrated into the overall systems, added Scott. These may include hot-gas bypass, variable-speed condenser fan motors, and controllers driving the condenser fan motors to adapt condenser operation to changing ambient temperatures (effectively by creating floating head pressure), LED lights with lighting sensors, and improved evaporator coils.

Publication date: 6/8/2015

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