Q: I can't afford geothermal. Is an air-to-air heat pump my best option for heating? I do not have natural gas. Most homes around here [in New York] are heated using oil. I have no heating system at all. What would you recommend? Also, I should mention I have a 7.7 Kilowatt PV system on a south-facing roof, producing about double my electrical needs.
Sent by Chris
Editor: Here's what our friends at Green Home Guide say.
Answered by Answered by Randy Potter, EarthBound Homes:
Air-to-air heat pumps are a great efficient technology for heating and cooling living spaces. Like your refrigerator, heat pumps use electricity to pump refrigerant and transfer heat from one space to another.
- When we transfer heat from within our home to the outdoors, we call it "air conditioning."
- Conversely, when we transfer heat from the outdoors to within the home, we call it a "heat pump."
Simple and relatively inexpensive (~$1,000-$2,000) heat pump systems called mini-splits can be a nice solution. A mini-split is a small unit which is split into 2 pieces:
- The first piece is the evaporator/fancoil unit, which is generally wall-mounted to an exterior wall. This unit acts as your ductwork as well (this is where the heat/cool comes out of).
- The second unit is the actual compressor/condenser, which sits on the ground on the exterior side of the wall that holds the evaporator/fancoil unit. This is similar to the setup that many people have seen with air conditioners where the noisy compressor is outside the house.
We use these mini-split systems in California all the time, and our clients love them. They provide very efficient heating and cooling, they create automatic zoning (since each unit operates independently), and they are relatively inexpensive.
The one issue that you may face when heating in New York is pretty obvious; a heat pump works by pulling heat from the outside air, so if there is no heat to pull (i.e., on <0 degree days) the system cannot provide heat. This means that you might have to keep lighting the wood stove during the really cold periods of winter.
- The good news is that the same unit can provide wonderfully efficient air conditioning for you in the summer.
- The other good news for you is that these units run on electricity, which you are currently overproducing for free, so in theory you can run a mini-split system for free.
As far as systems go, we like the Fujitsu Halcyon products [PDF]. They offer a range of sizes as well as a concealed ceiling mount system if you want to go that route. They also have built-in inverter technology which allows the unit to run at variable speeds for maximum efficiency.