Heat pump installation: what to expect and how to choose an installer

Why the installation matters as much as the equipment

A Department of Energy checklist, content by Pacific Northwest National Laboratory, says a quality installation is integral to a well-performing system. It says nearly half of heating and cooling systems in U.S. homes are not installed to manufacturer's instructions. As a result, it says, they perform below rated capacity and efficiency.

ENERGY STAR, a program of the EPA and the Department of Energy, lists what poor installation can lead to. Its list includes insufficient dehumidification, dust from leaking ductwork and poor air distribution.

The Department of Energy checklist is meant to be signed. It says the contractor shall check each box, then sign and date it to certify the work is completed. That gives you a simple ask: request a signed checklist like it with your job.

Sizing and a matched system

The Department of Energy checklist calls for a room-by-room load calculation under Manual J. Manual J is the method published by the Air-Conditioning Contractors of America (ACCA).

The same checklist says the heat pump should be sized under ACCA Manual S, based on the Manual J results.

One manufacturer's instructions say that when a condensing unit or air handler is replaced, the system must be manufacturer approved and AHRI matched, and that installation of unmatched systems is not allowed. AHRI is the Air Conditioning, Heating and Refrigeration Institute, whose certificate documents a matched system.

Another manufacturer recommends installing only approved matched indoor and outdoor systems. It lists maximum efficiency, optimum performance and the best overall system reliability as some of the benefits. ENERGY STAR says your contractor should provide an AHRI certificate to document that the system was properly matched.

Where the outdoor unit sits

The outdoor unit needs a firm, level base. One manufacturer says that at ground level the unit must be on a solid, level foundation that will not shift or settle. It adds that a concrete slab raised above ground level provides a suitable base.

Frost can build up on a heat pump's outdoor coil, and the unit runs a defrost cycle to melt it. One manual, in a note on areas of heavy snow accumulation or prolonged continuous subfreezing temperatures, says heat pump bases have cutouts under the outdoor coil to drain that frost. It says to place the unit so defrost water and ice can drain freely.

Another manual, for units installed where snow accumulation and prolonged below-freezing temperatures occur, says the drain holes in the base pan must not be blocked. It says the pad must be level and high enough above the ground to allow for drainage. It also says to check local codes for tie-down methods and protocols.

Flood elevation and wind have their own section in heat pumps in Florida.

Leave room for service. One manual calls for 24 inches of clearance in front of the control box and on any other side that needs service. The installer should follow the clearances in the manual for your unit.

Heat pump checks: reversing valve, backup heat, defrost and charge

One heat pump manual says the reversing valve energizes in heating and cuts off in cooling.

Some heat pumps also have electric auxiliary heat. One manufacturer's wiring list names an electric auxiliary heat signal, and its checkout list includes this item: verify operation of supplementary electric heater. Ask the installer to show you that check was done. Our auxiliary heat guide explains more.

One manual says heat pumps are equipped with a time/temperature defrost control with field-selectable defrost intervals.

One manufacturer says the proper method of charging a heat pump in heating mode is by weight, with additional charge adjustments for line size, line length and other system components. It says to make final charge adjustments in the cooling cycle.

Ducts, airflow and the thermostat

The Department of Energy checklist says exposed ducts should be inspected, and damaged or disconnected ones repaired or replaced. Visible leaks should be sealed with UL 181 tape and/or mastic.

The same checklist says the contractor should check whether the ducts are properly sized and make recommendations if they are not. ENERGY STAR's bid checklist suggests asking whether the contractor will test the largest system your existing ducts can handle.

Airflow is measured, not guessed. The checklist says airflow across the coil should be tested to confirm it is within the range the manufacturer specifies. One manufacturer says airflow and total static pressure for the indoor unit should be verified before attempting to charge the system.

If the thermostat moves, the checklist says to put it on an interior wall. It should be away from registers, appliances, lights, exterior doors, windows, skylights, direct sunlight and drafts. The evacuation and charging steps on installation day are covered in AC installation done right.

How to choose the installer

Start with the license. Florida's Department of Business and Professional Regulation (DBPR) runs a public search at MyFloridaLicense.com. It says users can verify licenses by name or license number. Florida HVAC contractor licenses explains the license types you may see.

One manual says it is meant for qualified licensed service personnel. Another says that where a license is required, only licensed personnel should service the equipment.

Refrigerant work has a federal rule as well. The EPA says its regulations (40 CFR Part 82, Subpart F) under Section 608 of the Clean Air Act require that technicians who maintain, service, repair, or dispose of equipment that could release refrigerants into the atmosphere must be certified. Under 40 CFR 82.152, activities reasonably expected to violate the integrity of the refrigerant circuit include but are not limited to attaching or detaching hoses and gauges, adding or removing refrigerant, adding or removing components, and cutting the refrigerant line.

Then compare what each installer will put in writing. The Department of Energy checklist page tells contractors to advise customers to insist that every bid include its checklist. It says this is to ensure equivalent quality work. Useful questions from the ENERGY STAR bid checklist include these:

Will you calculate the size using Manual J? Will you install a properly matched indoor coil and outdoor unit? Will you confirm proper levels of refrigerant and airflow across the coil? Will you leave the manuals, the Manual J calculations, the AHRI certificate and your test records with me?