In colder climates, could an air-source heat pump be put in an attached (insulated, but not heated) garage as a way to improve its operating efficiency?
James Carrow • via email
Air-source heat pumps (ASHPs) work by extracting heat from ambient air and need an ample supply to work effectively. Installing an ASHP in your garage would suck out all of the warmth from the air captured there, effectively turning that space into a freezer, colder and colder until it would be impossible for the heat pump to extract heat effectively. Installing an ASHP inside a garage can void your manufacturer’s warranty and may cause permanent damage to the unit.
So while you want to avoid installing the ASHP in an enclosed space, installing one to replace an existing inefficient heating system, such as a furnace or boiler, can be a very good investment. I live in upstate New York, where many people are finding it harder to afford to heat their homes, especially with electricity, oil, or propane.
In my area, minisplit, hybrid, and geothermal heat pump systems are popular. Minisplits are the least expensive and easiest-to-install systems. A hybrid system is an air-to-air heat pump installed with a 92% or higher efficiency propane gas furnace. Geothermal heat pumps have the highest installed cost, but offer the greatest savings. Ground- or water-source heat pumps qualify for a federal tax credit of 30% of the installed cost.
Keep in mind that installing any heat pump is not a typical do-it-yourself project. Some manufacturers do not honor any warranty on equipment installed by homeowners or purchased on the Internet—so even though the online price may look great, you may end up paying a lot more to repair or replace equipment if it’s not properly sized and installed.
If you heat with electricity, oil, or propane, you should look at heat pumps as a way to reduce your heating cost. It would be wise to make energy-efficiency improvements before upgrading your heating equipment.
Bob Zima • Certified Radiant Professionals Alliance radiant heat instructor