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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

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    This will completely depend on the fuel costs in your area (and over time), and personal preference. – Tester101 Sep 1 '15 at 2:23
  • Okay. Thanks. For the sake of argument, assume my preference is electric heat. Electricity is $0.063042 per KWH here and oil is around $2 per gallon. Also, for the sake of argument, lets assume those prices are static and if they do increase it will be in equal proportion. – Chuck D Sep 1 '15 at 2:49
  • @ChuckD: are you sure your electricity is only $0.06/kwh? That is freakishly low for New England. I would guess it is probably more like double that, maybe triple in the winter when electricity prices rise due to natural gas shortages. If you are looking at your bill, make sure you add up all the charges for supply, delivery, fees, taxes, etc. – Hank Sep 1 '15 at 18:47
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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.

  1. 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.

  2. 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....

  3. 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.

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    You have not met modern low-temperature air-air heat pumps, which can work effectively down to -5F or less. The model mentioned in the question states: "Rated heating capacity is maintained up to 20°F. This new model can operate down to -5°F." – Ecnerwal Sep 1 '15 at 3:42
  • I agree that electricity is generally more efficient than a combustion based heat source, but I disagree that electricity is 100% efficient in its conversion to heat energy, especially in electric baseboard heaters. – BrownRedHawk Sep 1 '15 at 14:11
  • @BrownRedHawk: In efficiency discussions, I find there is usually some confusion whether one is actually talking about engineering conversion efficiency or bang-for-the-buck efficiency. – wallyk Sep 1 '15 at 14:23
  • Thanks for your excellent answer. Speaking in general terms, what are your thoughts on long-term reliability and equipment costs? The heat pumps are complicated machines and seem to only last around 10 years on average. – Chuck D Sep 1 '15 at 14:31
  • @Chuck D, unfortunately I don't know too much about the long-term reliability or equipment costs; I suspect there's a wide range for any option and usually there's a trade-off as well - The more you pay up front, the more reliable. Something others have pointed out, though, is that you probably need to consider reliability of the electrical source as well. It does you no good to have a great electrical HVAC system if the power goes out for 5 days in the middle of a storm. Probably want to have a back up plan in that case, which is going to be a fuel. Even generators require diesel. – Joel Keene Sep 2 '15 at 19:07
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The operating range for the Fujitsu 15RLS2 to heat is -5°F to 75°F according to the specification. As long as temperatures are not below that for an extended time, this looks like a very good choice.

As for whether to significantly rely on electric heat sources, I have pause. We have removed baseboard heaters and installed a gas fireplace insert to address long power outages—which only occur during heating season. One unfortunate characteristic of the Pacific Northwest is winter windstorms, tall trees, and power lines not playing together nicely. Last winter we were without power totaling approximately four days over five occurrences.

If power interruptions are not a concern, whether because power is reliable or you have a generator, UPSs, etc. then I think it is smart to be less polluting while also reducing energy costs. Oil is eventually going to go up in price, affected mostly by non-U.S. factors (right now it is at decades long lows adjusted for inflation) while electricity is more stable and mostly affected by U.S. factors.

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Also, consider Solar Power is getting cheaper every year, and thus electricity may essentially be free in 10 to 20 years. Solar coupled with something like a Tesla Powerwall will allow the solar generated electricity to be stored when the sun is not out. You know solar is starting to make inroads when utilities start fighting it like they are now.

This is looking at your question in the long view, but something to think about.

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    Oh boy! Too cheap to meter - where have I heard that before, Reddy Kilowatt? – Ecnerwal Sep 1 '15 at 12:53
  • Hey, it is not just me saying it: cleantechnica.com/2015/01/14/… – Off The Gold Sep 1 '15 at 14:02
  • It may be cheaper, but never pays for itself. Plus at least where I am in the NE there can be weeks with almost no sun due to heavy cloud cover that just won't leave. – Andy Sep 1 '15 at 22:56
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The winters are too harsh and unpredictable in the Northeast to rely mostly on electric heat. The wood stove is an OK backup heat source as long as the temperatures aren't extremely cold, and the outage isn't for more than a couple of days.

If you end up in a situation where the power is out for days, and there are sub zero temperatures, then you start running a big risk of freezing the pipes in your walls. The insulation you are adding may help to prevent this from happening a little bit, but you can never be too sure.

You should think about having a backup heating source. If it isn't oil, then your options are limited since you are not able to get natural gas.

There are a few other choices that I can come up with. You could get a gas furnace and run it off of propane, replace your oil burner with a wood burning boiler, or get a pellet stove.

Propane can be expensive, but if you only use it for heating to take the chill off, and don't use it for heating up bath water, etc. then it is fairly cost effective.

Pellet stoves are quiet, they heat up quite a bit of space, and are easy to use. All you have to do is load up the pellet stove every morning, and make sure it doesn't get clogged up.

A wood burning boiler could work in your situation because it would allow you to reuse the existing baseboard heat. It would also only run when you are heating, so there is a big savings in fuel costs.

It would be a good idea to price out each one of these systems and weigh the pros and cons. There are a variety of heating systems on the market, and I am not endorsing which one you should ultimately end up with.

  • The oil boiler uses electricity for pumps and possibly draft fan and ignition. Most gas furnaces require electricity as well. Electricity outages are not really a good argument against going all-electric. – littleturtle Sep 1 '15 at 20:41
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    @littleturtle: You are correct, virtually all furnaces require electricity to run. However it is perfectly feasible to run an oil or gas furnace (or pellet stove) from a generator whereas that would be impractical with electric heat. – Hank Sep 1 '15 at 22:21
  • @HenryJackson. Good point! I hadn't thought about that. – littleturtle Sep 1 '15 at 23:44

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