He also cited quiet operation, aesthetics, and comfort as consumer issues that may become contractor issues.

Being able to perform basic diagnostics, such as superheat and subcooling calculations, will help contractors and technicians make sure that heat pumps are installed and serviced as they should be.

INSTALLATIONS AND REPLACEMENTS

"Older installations that were sized primarily for heating may not have adequate ductwork for cooling requirements," Lashar said.

Granderson said that during installations, particular care needs to be given to the air side. "Heat pumps are not as forgiving as conventional air conditioners," he said. "The contractor really needs to pay attention to the details. The single largest issue is inadequate airflow on the indoor side."

The cause, he said, could just be a poor or undersized duct system. "The indoor unit cannot move the air it needs to. During heating operation, it's really critical. If the airflow is not correct, it skews the refrigeration system's operation, which winds up having an adverse impact on the refrigeration side. Techs may misinterpret this as a refrigerant problem and add or remove refrigerant, and it's really an airflow problem."

Duct leakage can lead to problems, agreed Lashar. "Older installations that were put in before new, stricter building codes may leak up to 20 percent or more of the total air volume, reducing efficiency and airflow to the space," he said. "In many cases, the ductwork is inaccessible and cannot be changed. These issues, however, need to be addressed by the dealer as best as possible."

Systems that use R-410A have special issues. "Refrigerant and oil incompatibility and coil surface area are just a couple of issues that must be addressed," Lashar said.

Contractors need "complete understanding of the heat pump system, not only the cooling side but the heating side, airflow, and refrigerant - a good global understanding of heat pumps," Granderson said. "They simply may not understand that the ductwork is undersized, or the refrigerant line is too small, or coils are mismatched. You can get into trouble very quickly - it really throws the refrigerant side askew very quickly."

These problems aren't new, he added. But they are more critical when it comes to heat pumps, than with cooling-only central systems. And newer systems may be more strongly impacted. "An air conditioning system is a little more forgiving," Granderson said. "But the heat pump, because we're operating in cooling and heating, the tolerances, the forgiveness factor is not nearly as great."

COIL SIZE

"The new sizes can be a very big issue," Granderson said. "In a retrofit, for instance, they may not have room to put in a new indoor coil; we're dependent on the indoor coil for the heating mode. Performance and efficiency will suffer at the very least" if that indoor coil is not properly matched to the new system.

"In the long run, it will be better for the homeowner to have the entire heat pump system replaced," said Lashar. "They will gain the benefits of motors that are more efficient, and compressors and evaporator coils that have been designed to provide optimal efficiency for its matching heat pump."

In addition, "Both service and installation can and will be substandard unless all technicians are properly trained," Lashar said. "Risks may seem larger when it comes to an improperly installed system, but try to explain that to a homeowner who has had to meet a service technician at home on numerous occasions because of a poorly serviced or installed unit."

EQUIPMENT CHANGES

"Our product incorporates a control board for the outdoor unit that monitors the compressor," Granderson said.

"It's a diagnostic aid for the technician called the Comfort Control system from White-Rodgers. It offers active protection and monitors the system; a pressure switch communicates to the control, so the technician has a starting point for troubleshooting." A flashing light alerts homeowners to potential problems.

"The ECM motor also helps heat pumps go beyond those airflow issues," Granderson said. Using a programmed configuration and dipswitches, the technician can set up the unit to deliver a certain amount of airflow.

"The motor can ramp up or down to deliver the correct amount of airflow. It can overcome poor duct systems to a point." The ideal solution, of course, is to fix the ductwork.

Lennox said it has "continually tried to improve upon heat pump reliability and the tools provided to service technicians." The Lennox System Operations Monitor (LSOM) can monitor and collect data to provide visual indicators of potential system faults. The company says this "greatly improves troubleshooting accuracy and technician productivity."

Demand defrost boards with self-monitoring diagnostics can sense the temperature on the condenser coil and activate the defrost mode as needed, the company said. Specific to R-410A systems, the company uses specially designed scroll compressors and reversing valves with a more robust slide mechanism.

York's 18 SEER Affinityâ„¢ unit uses the Ultratechâ„¢ compressor as part of the QuietDriveâ„¢ system.

"QuietDrive utilizes a swept wing fan design, isolated compressor compartment, composite base pan, and two-stage cooling to provide four times' quieter operation and 60 percent more energy-efficient performance," Lashar said.

The Affinity 8T heat pump features hot heat pump technology "that produces discharge temperatures that are, on average, 10°F warmer than the discharge temperatures of standard heat pumps," he said. The unit can reach up to 18 SEER when matched to a York variable-speed furnace or air handler. It is available with HSPF ratings of 8.0 through 8.5, and is Energy Star® qualified.

The Affinity heat pump offers a full-end, full-service access panel with a handle, Lashar said an isolated compressor compartment, easy-access side-discharge service valves, and an adjustable knockout plate for electrical whips. The unit also features a solid-core filter-drier, demand-defrost board with service analyzer capabilities, integrated control, fault code retention, hot heat pump and fossil fuel jumpers, high- and low-pressure switch connections, and special features to protect a home against pipe freeze-ups.

STILL RELIABLE

"Dealers must educate homeowners and be sure to offer the choice that will provide the highest level of economical comfort," he said. "With the recent jump in gas prices, even without local utility rebates, heat pumps are once again a viable option in most parts of the country."

"In those situations where the equipment isn't properly matched and indoor airflow is inadequate, [consumer perception] will be at risk," Granderson said. "If those are done properly, it will be on the flip side; it will increase reliability."

Publication date: 05/22/2006