Bruce Saller, ADVANCE CONTRIBUTOR

If your house has hot water heating (i.e. radiators) and you are dreading the high cost of heating oil this winter, you finally have another option: Air-to-water heat pumps are now available in our area. They are similar to traditional air-to-air heat pumps except the inside unit heats water instead of air.

The air-to-water heat pump is very efficient, and you can find systems with coefficient of performance ratings around 4 (1 kilo-watt hour of electricity provides 4 kilo-watt hours of heat). They have been used in Europe for decades and are finally being manufactured in the US. Like the air-to-air unit, the system needs to be backed up with either an electric resistance heater or an oil boiler. If desired, you should be able to use your existing boiler as the backup.

The cost of the system depends on the capacity of the unit and other installation factors and will typically run between $10,000 and $25,000. I haven’t found a Dominion rebate or tax credit for these systems, but some manufacturers are offering rebates.

The heat pump uses $1.59 of electricity to provide the same amount of heat as burning one gallon of fuel oil. The average price of a gallon of fuel oil in Fredericksburg is currently $5.50, so your heating costs should be 71 percent less with the air-to-water system. If you are spending $600 per month on fuel oil, you should save $420 per month.

If you have an oil-based air furnace, you have the same options. You can install a traditional heat pump with electric backup or install a dual fuel heat pump and retain your oil furnace. Either option should save you hundreds of dollars a month on your heating bills. The cost of the system should be between $5,000 and $15,000.

The payback period for switching to a heat pump will vary but should be less than 10 years.

(Here’s how the math works, for inquisitive minds: 1 gallon of fuel oil provides 138,500 British Thermal Units (BTUs). Typical older oil furnace efficiency is 87 percent. There are 3412 BTUs in a kilo-watt hour. Use a coefficient of performance of 4 and an electricity cost of $.18 per kilo-watt hour. So, the cost of the heat pump to provide the same heat as a gallon of fuel oil is 138,500 x .87 / 3412 / 4 x $.18 = $1.59.)

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Bruce Saller is a retired systems engineer with degrees in electrical engineering and computer science.

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