A super-efficient geothermal heat pump shown with and without the front cover. Notice the large air cleaner and water fittings for also heating hot water. Photo credit: Waterfurnace
Sometimes in replacing heating and cooling systems, it can make economic, environmental and lifestyle sense to switch to an entirely different type of heating source for your home. The costs of fuels, such as natural gas, propane, heating oil and electricity, have shifted dramatically over the past decade. Many new heating systems last 20 years or more, so with wide variations in fuel costs, long-term estimated operating costs and paybacks are not always reliable.
Electricity prices are the most stable and will probably continue that way. For homes heated with electricity, air-source or geothermal heat pumps make good sense because they can heat, as well as cool, your house efficiently.
A standard air-source heat pump is basically a central air conditioner with a few extra parts. The outdoor unit looks exactly the same as a central air conditioner. It is called a heat pump because it literally pumps heat out of your house (cooling mode) or into your house (heating mode) to or from the outdoor air around the outdoor compressor/condenser unit.
Among central heating and cooling systems, geothermal heat pumps provide the highest efficiency and lowest year-round utility bills. While geothermal heat pumps have much higher initial installation costs (due to the need to place loops, or tubing, to run through the ground or to a well or pond), the federal stimulus bill provides consumers (through the end of 2016) a 30 percent tax credit on the cost of putting in a geothermal heat pump system, making them much more affordable. There is also a 35 percent North Carolina personal tax credit available through 2015 for geothermal systems.
The primary advantage of installing a heat pump of any kind is they can be used year-round for both heating and cooling. This means year-round savings and a shorter payback period. In contrast, a super-efficient furnace gets used only during winter and a central air conditioner only during summer.
I use a portable heat pump in my own home/office for year-round savings. It cools the room during summer and also functions as an efficient portable heater during winter. It produces 14,000 Btu per hour (Btuh) of cooling and 11,000 Btuh of heating. This is much more heat output than a standard electric space heater using the same amount of electricity during winter.
The efficiency of a portable air conditioner is similar to a window air conditioner. Although this is less efficient than the newest central air conditioners, using one can still save money. By keeping just one or two rooms comfortably cool with clean air, you can set your central thermostat higher and save electricity overall. They are typically mounted on casters so they can be easily rolled. Use it in the dining room for dinner, roll it into the living room for television, and then to the bedroom for sleeping. Most operate on standard 120-volt electricity, so they can be plugged into any wall outlet near a window.
A portable air conditioner/heat pump operates similarly to a typical window unit. The internal rotary compressor, evaporator and condenser function in the same way. The primary difference is it is not on casters and rests on the floor.
Every type of system requires some maintenance that can increase the overall costs. A heat pump requires about the same amount of service as an air conditioner.
About the Author
James Dulley is an engineer and syndicated columnist for the National Rural Electric Cooperative Association. www.dulley.com