I am in the process of overhauling my home heating and plumbing. I bought a 2600sq/ft 1980s Cape Cod in southern Maine on the coast. I've reinsulated the walls and roof and am continuing to make improvements in sealing the house. Overall, the insulation is pretty good. The house is built on a slab with a 5 ft high frost wall.
Currently I have a old noisy oil burning boiler/on-demand water heater and forced hot water baseboard heating. I also installed a Jotul Oslo wood stove and a Fujitsu 15RLS2 heat pump. The boiler is a mess, the previous owner never serviced it. It has broken down twice and I have dumped about $1500 into it within the past 18 months.
This past winter we relied almost exclusively on the wood stove and heat pump which got me thinking. Do I even need this oil boiler? Even in the summer, when it is just heating hot water, it can easily go through 60 gallons of oil per month. We do not have natural gas lines in my town.
My thought is to scrap the oil boiler, get another heat pump, and install electric baseboard as a backup. I would also install a heat pump hot water heater. In the long run I plan to install a solar electric system…
Is this plan crazy? Should I keep some sort of fossil fuel based heat source? Is the electric baseboard a bad idea?
Here are temperature statistics for the town I live in: http://temperature.weatherdb.com/l/3943/Cape-Elizabeth-Maine
Best Answer
First step is to convert those prices into something you can compare on equal footing. $0.063042/kWh = $17.50/GJ, for oil, $2/gal = $13.7/GJ
So, superficially, oil is cheaper than electricity for the same amount of energy. However, there are a couple of other things to consider.
Oil combustion is only about 75 - 90% efficient at heating because you have to exhaust the products of combustion, losing some heat in the process. Electricity on the other hand, when converted directly to heat (like in a baseboard heater, or electric furnace) is 100% efficient.
Electricity can be used to run a heat pump which, instead of turning the energy source directly to heat, uses a refrigerant to move heat from outside, allowing you to get 2 - 3 GJ of heat into your house for every GJ you put into the heat pump. This GREATLY improves the cost effectiveness of electricity... but....
Heat pumps typically have a minimum temperature at which they will operate effectively. This temperature will depend on the model and they are getting much better, but you may still have to depend on resistive heating on the coldest days of the year.
Given your assumptions, the prices you have thrown out, it seems like it will be a wash, or slightly cheaper to use electricity. Long term reliability, equipment costs, and other concerns may be a different story, however.