Heat pump SEER ratings now reach well over 20, but if the equipment is not installed correctly, homeowners will not achieve anywhere near the level of energy efficiency (or comfort) they purchased. This is evidenced by a recent study from the National Institute of Standards and Technology (NIST), which found that improper installation of heat pumps may increase household energy use for space heating and cooling on the order of 30 percent over what it should be.
According to the study, the most common installation problems include duct leakage, refrigerant undercharge, oversized heat pumps with non-oversized ductwork, low indoor airflow due to undersized ductwork, and refrigerant overcharge. Each one of these issues has the potential to cause significant performance degradation and increased annual energy consumption for homeowners. Homes often have a combination of these issues, which can lead to expensive, but necessary, repairs.
Charlie B. Thompson, operations manager, Munn’s Sales and Service Inc., Fruitland Park, Florida, has seen his share of poor heat pump installations. About 65 percent of his customers utilize heat pumps, and when he works on systems his company didn’t install, he often finds undersized ductwork to be a problem.
“If we suspect undersized ducts, we will test the static pressure of the duct system,” Thompson said. “If the static pressure is too high, we’ll physically inspect the ductwork to confirm our static pressure readings.”
Unfortunately for homeowners, tracking down the ductwork problem can be much more affordable than actually fixing the problem.
“It’s definitely in the customer’s best interest for a contractor to properly size the duct on the initial installation rather than save a little money by undersizing the duct,” said Thompson. “Enlarging ductwork in a retrofit situation can quickly become costly.”
About 50 percent of Matthews, North Carolina-based McClintock Heating, Cooling, and Electrical Inc.’s customers use heat pumps, and company president, Rob McClintock, maintains ductwork is the primary problem when it comes to older heat pumps.
“We regularly see duct systems that were improperly designed and installed, leaky, and coming apart,” said McClintock. “Design issues can contribute to an overall lack of proper airflow, and airflow deficiencies can result in an inability to properly charge the system. This can cause premature compressor failures, system component failures, drafty winter operation, high utility bills, and an overall dissatisfaction with the system itself.”
Sometimes it is not a design issue that causes a heat pump to perform poorly; it is a lack of regular maintenance. To determine whether there are any design or neglect issues, McClintock and his crew run airflow tests on every heat pump system they encounter. After establishing a baseline, he can tell if the system is operating within the manufacturer’s specifications.
“Of course, this takes a little more time, but we find it can give us an insight into what may be the next thing to go wrong and then counsel the homeowner accordingly.”
John Poyle, president, Hagerstown Heating and Cooling, Hagerstown, Maryland, is used to working with heat pumps as 90 percent of his customers have one installed. He encounters improperly installed heat pumps all the time, and many have the problems listed in the NIST study. Additionally, a lack of proper clearance around heat pumps is a common issue. This usually occurs when contractors install new, energy-efficient units.
“The new, higher-SEER units are physically bigger, and when contractors place them in the same location as older units, air restrictions may occur, which can hinder system performance,” said Poyle. “We move or modify heat pumps every year due to air restrictions, and it can be costly. In some instances, line sets and the line voltage have to be rerouted in order to move the unit to a different location. These repairs can exceed $1,300 for something that the previous contractor could have done for half the cost during the installation.”
Of course, the solution to all these problems is to correctly install the heat pump in the first place. And, whether it’s new construction or replacement, all successful installations start with conducting a comprehensive load calculation, said McClintock. “This calculation should include all the important things about a house, such as all building materials, window coverings, direction to the sun, specific location of the house, intended temperature targets, etc.”
Once the load calculation is finished, a duct system, if new, can be properly designed. If it is a replacement system, it can be evaluated, said McClintock.
“If replacing a system with the same size equipment, contractors should never assume the duct system is properly designed and sized,” he said. “Remember, a system’s efficiency is only as high as the weakest link, which, in many cases, is the duct system.”
Once the heat pump is installed, be it in new construction or as a replacement, a commissioning report should be conducted to ensure the system is operating per manufacturer specifications.
“This report should begin with airflow verification, because if the system does not meet the proper airflow requirements, then virtually no other test can be performed,” said McClintock. “Performing a commissioning report takes time, teamwork, and sometimes more money than was originally allotted. But, this will almost always save money over time and result in a happier customer.”
Poyle agrees that commissioning each heat pump installation is a good idea, because it creates a company culture in which everyone has skin in the game.
“A quality control system shouldn’t make anyone feel like they can’t be trusted,” he said. “Instead, it should be viewed as bragging rights, because no one can find anything wrong with the installation. It’s a great way to create competition and recognition within the company and a good way to identify poor craftsmanship and attitudes.”
Performing a standardized startup and commission on each installation is a requirement at Munn’s, which utilizes a checklist for both retrofit installers and new construction startup technicians to follow. The checklist includes, among other things, inspecting all ductwork on each system change out, setting up fan coil blower speeds to achieve proper airflow across the indoor coil, and measuring the refrigerant charge to make sure it adheres to manufacturers’ specifications.
“An ounce of prevention is worth a pound of cure,” said Thompson. “We are the professionals. We have complete control over whether customers have properly operating, comfortable systems or miserable, uncomfortable homes. If we don’t have complete control, then who does?”
Publication date: 5/29/2017