April 08, 2020

Is hybrid heat pump the best choice?

Dear Jim: I want to install the most efficient heat pump for lower heating bills, but I also want low summer cooling costs. Is a hybrid heat pump a good choice and what features should I look for in a heat pump?

– Bob M.

Dear Bob: Installing a high-efficiency heat pump is certainly a choice most homeowners should consider, particularly with volatile natural gas and oil prices. Electricity prices do increase over time, but they tend to be more stable than other energy sources.

Depending upon the outdoor temperature, a heat pump can produce $3 worth of heat for each $1 on your utility bills.

You often hear people say that heat pumps produce “cool” heat, which is uncomfortable. This may have been true with the early designs of heat pumps many years ago, but new ones can keep a house as comfortably warm as a gas, oil or electric furnace. I use a heat pump in my own all-electric home.

Installing a hybrid heat pump system is a good choice if you already have a functioning gas or oil furnace or you are building a new home and also air-condition your home during the summer. Sometimes the heat pump is used to heat your home and the gas or oil furnace comes on other times.

Heat pumps lose efficiency as the outdoor temperature drops because they draw their heat from the outdoor air. At some outdoor temperature, the gas or oil furnace becomes less expensive to use. Your heating contractor will set the switch-over (heat pump to gas or oil) point based upon several factors to provide the least expensive heating and best comfort.

Heat pumps are basically central air conditioners that run in reverse during the winter. Instead of pumping heat from indoor air to the outdoors during summer, they pump heat from outdoor air indoors during winter.

The additional components and controls cost several hundred dollars more than an equivalent central air conditioner. When making your decision to buy a heat pump, consider the same features as you would when selecting a central air conditioner. Always have your heating contractor do payback analyses on several models with various efficiencies and comfort features. There are also environmental factors.

A more efficient one produces fewer greenhouse gases and R410A refrigerant is ozone-friendly. The most efficient heat pump, which also provides the ultimate comfort, is a two-stage model with a variable-speed indoor blower motor. Both heat (winter) and cooling (summer) outputs vary depending upon the heating and cooling needs of your home. During mild weather, it runs slower, but longer. A less expensive option is a single-stage model with a scroll compressor. To improve comfort, a variable-speed blower can be used with a single-stage model. Combined with a matching thermostat, this provides control of both the indoor temperature and humidity level.

Write for (or instantly download at www.dulley.com) Update Bulletin No. 763 – a buyer’s guide of the 20 most efficient, comfortable heat pumps listing stages, efficiency, compressor type, refrigerant, size, blower speeds, and a savings-and-payback chart. Include $3 and a business-size SASE.

Dear Jim: I recently moved from Michigan to southern North Carolina. We always used a whole-house ceiling vent fan in Michigan. Since this is a warmer climate, should we install one in our new home here?

– Jo Ann H.

Dear Jo Ann: A whole-house fan can be effective in almost any climate. In warmer more humid climates, such as the Carolinas, or hot climates, such as Phoenix, you might not run it as often as in Michigan.

Even if the outdoor air is somewhat warm, a whole-house fan will create a comfortable breeze indoors at night. During extremely humid weather, avoid using it because it may increase the load on the air conditioner to remove the excess moisture the next day.

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