Buildings

Reasons for High Heating Bills

Q: I think my 5 year old heat pump may be wearing out. Any time the heat comes on, even if the outside temperatures are mild (40 50 degrees), the blue and/or red lights on the thermostat come on. Last year my power bill for January was $123. We had ice storms and frigid weather. This year a mild January the power bill is $198. What's going on?

A: I consulted with one of our engineers who is widely recognized as one of the country's foremost experts on heat pumps. Based on his comments, I would say that it's unlikely that your heat pump is "wearing out." Heat pumps are designed with a life expectancy of 20 years, and, with proper installation and maintenance, easily last 15-20 years. While certainly not impossible, it would be rare for the unit to be dead at such a young age.

As for the problem of the strip heat coming on (indicated by the light on the thermostat), even in relatively moderate weather: Sometimes we have seen situations where a homeowner complains about the heat pump blowing "cool" air, and the service person "solves" the problem by wiring the strip heat to come on whenever the compressor comes on. Have you had this situation? This could explain your high bill. If this is the problem, you need to get a service person out there to determine why the system is blowing cool air. It could be that there is too much air flow, that the system is improperly charged, that a supply register is improperly placed, or that there are leaks in the duct system. Once these problems are solved, the strip heat light should come on only at or below about 35 degrees F.

The combination of machines, buildings, and people create all kinds of possibilities for problems. Last summer I went out to a house where the people were very uncomfortable. In a wonderful house with a fully-finished walk-out basement, they could never get the upper level below about 80o and in order to achieve any level of comfort, the lower level became so cold that they were running space heaters. In August! Two contractors had suggested new windows as the solution to their problem — at a cost of about $30,000.

After some testing, I determined that one major problem was that the return duct for the upstairs was totally disconnected. The first clue was that the filter — which hadn't been changed in about six months — was perfectly clean. Obviously, no air was going through it.

I also found serious air leakage paths between the living space and the attic and lots of missing insulation in the attic. Over the years, various remodeling projects had been done which required re-wiring. The electricians had apparently pushed the insulation aside and left it. In addition, the overall insulation level in the attic was inadequate by today's standard.

They hired a heating & air conditioning contractor to repair the ducts, a remodeling contractor to do the air-sealing and repair the (necessary) damage made by the first contractor, and an insulation contractor to re-insulate the attic. Not only would they be more comfortable, I assured them, but their investment of about $3,500 would also cause their utility bills to go down.

They called at the end of December to tell me they were much more comfortable, but their electric bill was $100 more than last December. I suggested waiting another month, since some of the work was still going on in early December. At the end of January they called again. The bill was $150 more than last year, despite a very mild month. The only thing I could think of was that the five-year old heat pump wasn't working, and they were heating with strip heat all the time.

The heating contractor came back out to check the equipment. It turned out that they had installed a new thermostat last summer and wired it up wrong. The heat pump was fine — it simply wasn't wired to ever come on in the heating mode!