Restoration Guide: HVAC Heat Pumps

Editor's Note: This is article 6 of 16 in Chapter 8: The HVAC/Plumbing Guide of Old House Web's Home Restoration Guide. This guide was developed and edited for old homes from original materials in the U.S. Housing and Urban Development (HUD) Rehab guide.

6. HEAT PUMPS

Heat pumps are an option for an older home restoration when both heating and air conditioning are desired. However, they might not be the proper solution for every climate. This article helps you decide when heat pumps are a good choice for your old house heating and cooling needs and discusses the various types that are available.

Section 1--Are Heat Pumps the Answer for an Older Home Renovation?

Heat pumps were first introduced to homeowners during the 1950s as a viable solution for their heating and air conditioning needs. They are a single system that is usually fueled by electricity, and they do not have a need for vents or chimneys. Early reliability issues were solved, and today many new homes use heat pump systems.

The area where your old house is located can play a part in your decision as to whether you should install a heat pump as a part of your older home restoration. Heat pumps operate at peak efficiency when you have a great need for cooling, but your heating needs are moderate. If your heating needs are very small, such as areas of the Southeast or Southwest, then it may be more cost effective to install a separate electric resistance system, and an electric air-conditioning system. Old house owners in the Northeast or Midwest, where winters can be severe, may find that a gas furnace/air conditioning system is less expensive to operate.

Heat pumps do not operate well when the temperatures get very low, and a supplemental electric resistance heat system turns on to provide the additional heat needed. If your local climate has low temperatures which cause the supplemental heat system to operate on a regular basis, the system can become expensive to operate. Heat pumps are available with different efficiency ratings, and when comparing various heat pumps you should compare ratings based on the temperatures common to the area where the heat pump will be installed.

Section 2--Heat Pump Options

If you feel your old house's climate is suited for a heat pump system, there are several choices for your older home renovation.

2.1: Adding a Split System Air Source Heat Pump (ASHP)

This is the most common type of heat pump found in homes, and it provides air conditioning during warm weather months and heating during cold months. There is a supplemental resistance heating system for when it gets too cold for the heat pump to provide enough heat. If you feel that you are in an area where the supplemental heat may operate more often than you like, there are options for additional heat you can install to reduce the use of the resistance heat system.

2.2: Adding a Single Package Air Source Heat Pump

If your old house happens to be in an area where locating an outdoor heat pump compressor/condenser is difficult, there are heat pumps available in a single package. This unit is about the size of a furnace, and contains all of the components of a split system heat pump. The unit is positioned where it can use a fan to pull outside air into the unit and over the coils. The unit can produce more interior noise than a normal furnace.

2.3: Adding a Packaged Terminal Heat Pump (PTHP)

Packaged terminal heat pumps are similar to the single unit heating and air conditioning units discussed in Section 5. The unit fits through an exterior wall opening just as the heating and air conditioning unit does, but the PTHP uses an electric heat pump for heating rather than just the resistance heat provided by the heating and air conditioning unit. These units can be somewhat noisy.

2.4: Adding One or More Ductless Split Systems or Mini-Splits

This is an old house friendly heat pump system. If you have discovered during your older home restoration that there is no heat or cooling distribution system, and you don't want to reconfigure the house with ductwork, these split systems do not require any ducting. There is an outdoor condenser unit, but the indoor unit sits just inside the exterior wall and distributes warm and cool air from that point. You can connect several interior units to one exterior unit. A downside to ductless split systems is that they cannot distribute fresh air from the outside.

2.5: Adding a Ground Source Heat Pump (GSHP)

Ground source heat pumps use the heat of the ground as a source of heat rather than the outdoor air. Since the temperature well below the ground's surface can be warmer than the air temperature during cold months, this can be an attractive option for northern areas. It can also be more efficient than air source heat pumps in cold areas, as the below ground temperature doesn't change as much from day to day as the air temperature often does. The most common type of GSHP uses a closed loop of piping containing water or an antifreeze solution which is pumped to absorb the ground's temperature.