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Kentucky Living Home

Savings from the ground up

By James Dulley from June 2014 Issue

Savings from the ground up

Credit: WaterFurnace

The Earth's steady temperature belowground can keep your home comfy year-round using today's highly efficient, energy-saving geothermal heat pump systems.

I have an old inefficient propane furnace and central air conditioner. I was thinking of replacing them with a geothermal heat pump. Does this sound like a good idea and what types are best?—Steve H.

With all the problems last winter of propane shortages and the price uncertainty of natural gas, many people are considering geothermal heat pumps. In fact, I just installed a variable-speed WaterFurnace 7-Series geothermal heat pump in my own home. 

Instead of the outdoor condenser unit in a standard heat pump system, a geothermal unit uses liquid-filled (water/antifreeze mix) piping belowground. Most people install deep vertical loops, but I have a large back yard, so I installed a 5-foot-deep horizontal loop. Using the free heat from underground, my system produces more than $5 worth of heat for each $1 on my utility bill. 

The big advantage during the winter is the heating output of a geothermal system does not drop as it gets colder outdoors, which is when your house needs the most heat. For this reason, the backup electric resistance heating very seldom comes on with a geothermal heat pump.

In addition to being extremely efficient and comfortable during the heating season, a geothermal heat pump is also the most efficient central air-conditioning system available. 

Fan-speed strategies
The simplest design for a geothermal heat pump is a single-stage compressor, which is either on or off. The next step up in comfort and efficiency is a two-stage compressor. Most of the time, it runs at the lower-output speed. But when it cannot heat or cool your house to the thermostat setting, it automatically switches to the higher speed for more output. 

For the highest efficiency, I chose a variable-speed compressor and matching thermostat that can fine-tune the heating and cooling output to the instantaneous needs of my house. By constantly varying the output, it runs in more efficient, slower, quieter, and longer cycles. This is coupled with a variable-speed blower that matches the airflow from the registers to the compressor output for excellent comfort. And it provides good humidity control in summer. 

Check with your local electric co-op and geothermal heat pump vendor for how to qualify for a 30 percent federal tax credit (when installed by December 31, 2016) and a 30 percent state installation tax credit not to exceed $250 (when installed by December 31, 2015) for qualifying ENERGY STAR geothermal heat pumps.


EFFICIENCY BONUS
Give your water heating a boost
Adding an optional hot water assist unit to a geothermal heat pump system provides even more energy savings. During the summer, excess heat being pumped from the home's interior is routed to the water heater. During the winter, any excess heat being produced by the geothermal heat pump goes to the water heater. This can lower electricity use by the heating element to one-fifth the typical amount.



Mail requests and questions to JAMES DULLEY, Kentucky Living, 6906 Royalgreen Drive, Cincinnati, OH 45244, or visit www.dulley.com.