At what point are electric space heaters more cost effective than oil furnace heat?

[amyamanda]

I picked up two fairly new electric space heaters for free today. I thought perhaps at some point it would make sense to use them as a cheaper supplement to our oil furnace heat, or, if we decide to install woodstoves, to use them in the parts of the house with water pipes where the woodstove head doesn't permeate well and we'd worry about pipes freezing.

I'm wondering how one would figure out when cost of the electric space heaters (traditionally considered "expensive") trumps the cost of oil heat? Any ideas?

I wonder if we'll get to that point this winter.

ShaggyDaddy, are you reading? Somehow I'm guessing you'll have an answer to this one.

[4evermom]

I dunno but we use an electric space heater in the room we hang out in for the bulk of the day so we can keep the thermostat low. It's a big house so it makes sense to me that this would be cheaper than keeping the whole house at a comfortable temperature. Basically our living room and kitchen are the only warm places in winter and we just dash through the other parts except when we are in bed with a pile of blankets, lol.

[ShaggyDaddy]

you are in vermont, so lets assume 14.88 cents per kWh

Electric Space heaters are typically 1000-2000 watt so lets say average 22.32 cents per hour, using 1500 watt space heater in our example.

A passive space heater (no fan) will produce a maximum of 5,119.5 BTUs with 100% efficiency... the truth is space heaters are one of the most efficient converters of energy because most of the typical "loss" in electricity is heat... so I will use that number.

So basically you get 5119.5 BTUs for 22.32 cents every hour of operation.
or...

Now lets look at heating oil.

The most recent price I can find is 2.75/gallon in Vermont, so I will use that number.
1 gallon has 138,500 BTU again with not very much loss.

so basically:
Oil@$2.75/gal = 1.9 cents/1000 btu
Elec@14.88c/kWh = 4.4 cents/1000 btu
so...
Oil at $6.10/gal = 4.4 cents/1000 btu
That would be the break even point on electric vs oil.

Of course space heaters are portable, and can be used in just one space, sometimes if you only have central heat, you will "lose" tons of energy heating spaces you don't need to... but in general, in terms of thermal energy heating oil is insanely cheap.

[karne]

I'm not sure I'd be comfortable running space heaters in places I couldn't see them, and all day/night, ie to keep pipes from freezing. I know lots of people do it, but it seems every winter there are really terrible home fire stories that seem to be associated with space heaters. If I had the choice, I'd choose wood, and just keep your oil heat thermosta low, but above the freezing point for your pipes.

[amyamanda]

Thank you ShaggyDaddy, for accomplishing what my brain could not. I greatly appreciate your breakdown of prices, and I will watch for that $6.10 point (assuming electricity stays the same...though I can use your math now, with new numbers.)

karne, your concern merits research. Thank you.

4evermom, thanks for your BTDT!

Anyone else want to weigh in? (I this place, BTW - because I can ask this kind of question and get really thoughtful answers that help me make good decisions!)

[zersha]

Originally Posted by karne

I'm not sure I'd be comfortable running space heaters in places I couldn't see them, and all day/night, ie to keep pipes from freezing. I know lots of people do it, but it seems every winter there are really terrible home fire stories that seem to be associated with space heaters. If I had the choice, I'd choose wood, and just keep your oil heat thermosta low, but above the freezing point for your pipes.

:

I bought a brand spanking new space heater that was supposed to be super safe this last year. It suddenly got a weird smell, and a part of it started to go up in flames. Luckily, I was sitting right by it, so it was turned off within seconds, but if I hadn't been there, it could have been bad.

I won't trust a space heater again unless it's a dire emergency and we desperately need heat, or I can guarantee someone will be awake and attentive enough to notice any problems within seconds.

[cristeen]

Originally Posted by 4evermom

I dunno but we use an electric space heater in the room we hang out in for the bulk of the day so we can keep the thermostat low. It's a big house so it makes sense to me that this would be cheaper than keeping the whole house at a comfortable temperature. Basically our living room and kitchen are the only warm places in winter and we just dash through the other parts except when we are in bed with a pile of blankets, lol.

:

Since we have a very poor set-up for "central" heating in our 100 yo house, we would have to heat the LR/DR to a ridiculous temperature (think dripping sweat) to even feel it in the rest of the house. So we keep the central at 60 which keeps the living portion of the house from being ridiculously cold when the temp drops, the oven heats the kitchen all winter (I tend to cook a LOT when it's cold), and the office has a space heater with a thermostat. It's kept at 60 also, only turned up if we're in the room. Between the space heater and the extraneous heat given off by all the electric equipment in the office, the one room stays nice and toasty all winter and we don't have to worry about ridiculous heating bills. I did discover this last winter that it was cheaper to keep the space heater set to 60 at night rather than turning it off.

[Sharlla]

Here I'm looking at $120 max winter electric bill while my neighbor is raying $300 month gas. I'd say for me it's cheaper. We use those oil filled radiant heaters, they work great.