heating cost comparison

[Alan L.]

Let's see if I can explain this. With a heat pump you actually do get over 100% efficiency because you are pumping heat from the outside to the inside, so you are only paying to pump, not generate the heat. They don't usually call it efficieny, it's called COP (Coefficient of Performance).

One kilowatt of electricty will make 3412 BTUs. You can get 2 or 3 times this number of BTU per kilowatt with a heat pump. The problem is that this number depends on the outside temperature and at low temperatures you switch to strip heating which is 100% efficiency minus the duct loses. If your ducts are in unheated space this can be very significant and even in heated spaces the duct loss heat is going where you don't really need it. This was why the space heater are so good. You put them in the center of the room and they put the heat only where you are with a real 100% efficiency. The big negative of heat pumps is the life. They average about 12 years. I replaced mine at seven years and have spend far more on the initial cost and the annual mantenace than energy. I have an insulated concrete form house and so it is very well insulated. The heat pump was a new design and pulled off of the market by the supplier because of reliabilty. They gave me a new unit at seven yeras and I just paid for installation ($4000, not trivial) I think gas furnaces will last 30 years. A gas furnace with heat pump gives you the option of using the heat pump above 40 degress where it is effiicient and not stressed and the gas furnace below 40. You can change this temperature depending on how the prices of these energy sources change.

We have a heat pump but I can't imagine running any kind of heat if the temp is above 40 outside. We ran our window unit A/C last night set to cycle to maintain a temp of 60 in our bedroom. The low was about 43 or so, but the a/c ran quite a bit.

The problem with our building is that its hard to get any air ventilation in the house. You can open the windows and it still won't cool down. The only time we run heat is in the morning in the bathroom (even when its in the 20s outside) or if the temp stays windy and cold for 2 or 3 days in a row. Then, we need heat.

Without running heat, and temp of about 20 outside, it never gets below 59 degrees in the bedroom at night by morning. That would be too cool for sitting around the house, but under the covers its great.

 

[BobRip]

We have a heat pump but I can't imagine running any kind of heat if the temp is above 40 outside. We ran our window unit A/C last night set to cycle to maintain a temp of 60 in our bedroom. The low was about 43 or so, but the a/c ran quite a bit.

The problem with our building is that its hard to get any air ventilation in the house. You can open the windows and it still won't cool down. The only time we run heat is in the morning in the bathroom (even when its in the 20s outside) or if the temp stays windy and cold for 2 or 3 days in a row. Then, we need heat.

Without running heat, and temp of about 20 outside, it never gets below 59 degrees in the bedroom at night by morning. That would be too cool for sitting around the house, but under the covers its great.

I am speaking a little out of my area here, but here I go. Generally a heat pump is sized to have adequate heating capacity to heat a house down to around 30 degrees, this of course varies given the many variables involved. Given this situation propane or gas is a good choice if your climate gets below 30 for many days a year. It's not that the heat pump does not work much colder, as with my house it will provide heat down to below 20 and then the emergency heat is need if it stays there long enough. For your place you don't need any heat until it gets real cold. Because you are so well insulated, even at say 20 degrees you heat pump will heat your house and not have to run full time. For this situation where the emergency heat is only needed very rarely, then electric strip heating is your best choice. This is an over simplification as I don't know your climate or house construction. I have electric as the backup for the same reason. The emergency heat is only needed for a few hours a year typically. Please consult a profession who knows your climate and house construction for selecting a unit. This is not my profession. What is your house construction. Sounds like Adobe with very thick walls.