electric garage heater advice.

[Stickjiggler]

I am thinking about putting electric heater in my garage.What do you have and how does it work for you? Does it add a ton to your elec. bill. My garage is insulated 22 x 22 with 10 ft ceiling.

Thanks, stickjiggler

[PurpleFloyd]

Mine is similar in size to yours. I am not sure what brand or size electric heater we have but this year I have been running it just enough to keep the garage above freezing and it does bump up the electric bill.

[MARINERMAGNUM]

Heat it how much? Up to 70, or just above freezing?

I'm a little unsure,but I would guess you'd need at least 10,000 watts to get it toasty and have a quick recovery after a garage door is opened.

10,000 watts would be the equivelent of running 100-100watt light bulbs every time the elements are heating.

So ya,you'll definately see it on your bill.

Go L.P.

[Stickjiggler]

looking to keep around 40 degrees

[MARINERMAGNUM]

I see alot of folks using a single 220V,4500watt hanging heater for what you want to do.

Would be about like running another hot water heater-most of those have 4500watt elements as well.

[BobT]

When I installed the electric heating system in our home I did some research to figure out how much power would be required. The amount of required power will vary depending on the size of the room, how well the room is insulated, number of windows, etc. The general rule of thumb that I learned for a typical home was that for each cubic foot of area you need 10w of heat energy. So a 10’x10’ room with a 10’ ceiling would require about a 1000w heater. Is your garage finished and how well is it insulated. The cement floor will be cold and a terrific heat sink. Consider the garage door as these are usually not very well sealed or don’t provide much insulation. Consider the windows and how much heat loss you can expect there.

If your garage is insulated and you’re not going to try and heat it to 70 you might get by with about 5000w.

For what it is worth, electric heat is about the most expensive form of room heating there is unless you are taking advantage of your power company incentives like dual-fuel. Here’s the cost comparison of a couple examples. I don’t know what your actual price for these fuels are right now so you can just redo the math using real values if you want to compare apples to apples. Just replace the bold type values with real ones.

If you know the actual efficiency rating of the LP or Fuel Oil furnace being compared, you can use those values to recalculate it more accurately.

5000w/hour = 17,075 BTU/HR

Electric heat at the consumer level is very close to 100% efficient so we don’t have to de-rate it for this.

1 gallon of LP delivers approximately 91,500 BTU/HR. Answers ranged from 91.3 – 91.6 so I used 91.5.

LP furnaces commonly run at about 94% efficient give or take.

Therefore 17,075 / 91,500 / .94 = .2 gallons required to deliver 17,075 BTU.

1 gallon of #2 fuel oil delivers approximately 140,000 BTU/HR.

Typical fuel oil furnace will be about 82% efficient give or take.

Therefore 17,075 / 140,000 / .82 = .15 gallons required to deliver 17,075 BTU

Now we can calculate the hourly cost to run these three furnaces continuously. Obviously, they shouldn’t run continuously but this can show how they compare.

If electricity is $.10/KwH then $.10 * 5000w / 1000 = $.50 per hour cost.

If LP gas is $1.50/gal. then $1.50 * .2 = $.30 per hour cost.

If fuel oil is $2.80/gal. then $2.80 * .15 = $.42 per hour cost.

[JohnMickish]

Excellent info Bob, thanks for doing the research. If a guy can get on off-peak or whatever your REA calls it electric can be a pretty affordable way to heat, but if your paying regular prices not so much.

[MARINERMAGNUM]

Most of the el cheapo little heaters at Wally world are 1500watts on their high setting. Heating a 10x10x10 room with only 1000 watts may be possible,but recovery time would be awfully slow.

I have a buddy who put his Edenpure in his garage. Keeps it above freezing.

[BobT]

The information I posted is for a well insulated home and not a garage. That's why I pointed out that there are things to consider such as how well the garage is insulated, type of windows (single pane, double pane, triple pane, low-E rated, etc.), garage door (usually not well sealed or insulated), etc.

A 10x10 room is pretty small and 1000w will heat a house room 10x10x10 just fine. My home is about 1800sq.ft. with 9' ceilings on the main floor and 8' ceilings upstairs and I heat it with a 16Kw system. My home is old and only 2x4 construction so insulation is not up to today's normal home standards but the system actually recovers faster on the electric heat than it does using the forced-air fuel-oil furnace.

The OP said his garage was finished and 22'x22'x10'. By finished I assume it is insulated. The area he wants to heat is 4840cu.ft. If he was planning to keep it at 70 degrees I would recommend closer to a 10,000w system but because he indicates that he only wants to heat it to about 40 degrees I think a minimum 5000w system will be sufficient. The fact that he posed his question here suggests he might be installing this himself so up front labor costs are immaterial and he can always add additional heaters if needed.

[MARINERMAGNUM]

Yep,insulation is the key,and it pays for itself. Our neighbors have an old 2 story with poor insulation and 20 yr old windows,they burn around 2500 gal of lp per yr. We burn about 800 gal in a year,so it was money well spent considering all our appliances are lp fired also. Our elect runs a yearly average of about $65/[email protected] cents per kw/hr.

[Stickjiggler]

Thanks for the info folks. Yes the garage is insulated and rocked.