What is an air source heat pump and an add-on heat pump you ask?

Q.What is an air source heat pump?

A. A heat pump is a modified refrigeration machine similar to cooling in the summer, a heat pump heats in the winter. There are two types--conventional and add on.

A conventional heat pump consists of two sections and looks like any central, forced-air heating system with air conditioning.

One section resembles the familiar warm-air furnace and goes inside the house-usually in the basement.

This section contains the part of the heat pump called the A-coil plus electric heating which distributes the heated or cooled air throughout the house.

The other section goes outdoors and looks just like a central air conditioner. Refrigerant lines connect the two sections.

An add-on heat pump looks much like a conventional heat pump but differs in one way. The indoor part has no heating elements--just an A-coil installed in the ductwork atop your existing gas- or oil-fired furnace.

Q. How does a heat pump work?

A. Much like your refrigerator or freezer. In fact, the freezer provides a good example of how refrigeration extracts heat from very low temperature air. When the temperature in the freezer goes above a certain point -- usually at or near zero degrees Fahrenheit-- the freezer's thermostat starts the compressor. The refrigeration process removes heat from the near zero-degree air in the freezer. The extracted heat is "pumped" out of the freezer through condenser coils which release it into the air. You can feel the heat when you place your hand near the coils. If this heated air were distributed through a system of ducts, you would have, in essence, the heating cycle of a heat pump.

Remember, a heat pump does not produce heat. It moves heat from one space to another. in the cooling cycle, the heat pump removes heat from the conditioned space and releases it outdoors. During the heat cycle, the heat pump, by reversing the refrigeration process, takes heat from outdoors and moves it into conditioned space.

Conventional Heat Pump

Q. Can a do-it-yourselfer install an air source heat pump?

A. No! Installing an air source heat pump is not a do-it-yourself project. Seldom can anyone except a qualified heat pump dealer satisfactorily design, install, or service a heat pump system.

Q. What about maintenance of an air source heat pump system?
How much is really required?

A. Maintenance is an important consideration for any heating and cooling system. Owner performed maintenance of an electric heat pump is the same as for any central air conditioning. Specifically, after first shutting off all electric power to the unit, the owner should:

(1) Periodically inspect air filters (once a month is not too often) and clean or replace them as required.

(2) Periodically inspect and clean around the exterior of the outdoor unit to prevent buildup of leaves, grass clippings, and other debris. In winter, make sure snow does not build up around the outdoor unit because it will block necessary air flow.

(3) Oil the motor and/or fan bearings in accordance with the manufacturer's instructions.

In addition, you should have an annual maintenance check by a qualified heat pump dealer trained and equipped to service your particular unit. He can make a complete check of all heat pump system components. He also will check for refrigerant leaks and observe system operation. This step will help assure getting maximum efficiency and can help prevent problems by detecting deficiencies before they become major problems.

You can get maintenance and service contracts for heat pump systems installed in accordance with the manufacturers' specifications. These contracts are similar to the ones available for protecting major household appliances. It is RECOMMENDED that you buy a full service/maintenance contract (minimum of five years). Remember, it is the homeowner's responsibility to maintain the heat pump to the manufacturer's recommendations.

Q. How do the supplementary heating elements work in a conventional heat pump?

A. These electric heating elements, normally found in the indoor section of the heat pump installation, begin operating when the outdoor temperature drops below the balance point--between 25 degrees and 30 degrees. As outdoor temperatures fall, these elements come on and operate along with the heat pump which continues extracting heat from the outside air.

Q. Can I have a conventional air source heat pump installed in my present home?

A. Conventional heat pumps have replaced many existing heating systems. However, if you decide to install one, you should have your home insulated. Also, you should make any other changes necessary for efficient heat pump operation.

If you have questions about an existing home's installation, discuss them with a qualified heat pump dealer.

Q. What are the requirements for a good conventional air source heat pump installation?

A. To get maximum efficiency from your heat pump, you should:

(1) Choose a factory-trained and qualified dealer to install your heat pump. Most heat pump manufacturers conduct training schools for their dealers.

(2) Make sure the house is insulated and that all ductwork in unconditioned areas is insulated.

(3) Make sure the heat pump is sized correctly. That's necessary for efficient, economical operation year-round. The contractor should conduct a complete heat loss and heat gain study on your home to determine the size (capacity) equipment required. Also, the total connected wattage of the heat pump's supplementary heating elements should not exceed 80 percent of the wattage calculated as necessary to heat the home.

(4) Make sure the heat pump's indoor unit is located as centrally as possible.

(5) Make sure the dealer properly designs and installs the ductwork. Adequate sizing is VITALLY IMPORTANT to efficiency and comfort. That's because air distributed from a heat pump has a lower temperature than with other central heating systems and that requires a greater volume of air. Also, a greater volume of air is necessary for efficient cooling.

(6) Make sure supply registers are of the type for heating and cooling to ensure proper air distribution throughout the room. Also, use registers designed not to direct air onto the occupants of a room.

Install dampers in all branch ducts to permit adjustment of the air supply to each room.

(7) Follow the complete maintenance program recommended by the heat pump manufacturer. See your owner's manual for exact details.

Add-on Heat Pump

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