My heater for the winter

[2011laramie]

I have a 24x28 garage with r20 walls and r50-60 in the attic and no windows. It has a 45000btu modine hawt dawg forced air unit that is always at 5° unless im out there then its at 12°. The wife opens the door 2x a day when she leaves and returns from work.

A few years ago i bought a kill-o-watt monitor to track the heater usage.

Nov 1 I reset it to 0 kwh.
March 28 its sitting at 73.11kwh.
It has a running load of 235 watts.

These monthly averages from a local website.
November ave temp -7c
December ave temp -9c
January ave temp -11c
February ave temp -15c
March ave temp -8c

We've had lows down around -35c throughout winter

So averaged out over 5 months by my calcs, the heater runs on average 2hrs a day. 2hrsx45000x.8 =72000btu required a day average.

This post has no real purpose other than a summary. I knew my garage was cheap to heat, i just never knew how cheap.

 

[ripperd]

hmm, that is really clever. I just installed a 45kbtu heater this winter and have no real idea how much it runs, since the house is new too, I can't even compare prior year's gas usage. I do have a kill-a-watt meter, I should hook it up. Although it is getting warmer out and it is hardly running now.

 

[bmxdukie]

Interesting.
I have a 26 x 32 with a 45k reznor.
R22 walls and r30ish ceiling. Unit set at 50deg all winter. Unit ran but i still think its reasonable.
Likely $50 month?
Ill get a better idea next winter as thus winter i didnt get it hooked up until janurary.

 

[Streetbu]

So your Hot Dawg doesn't draw much electricity, but how much fuel does it use?

 

[JamesW84]

there are 3.41 btu/watt. 72000/3.41=21,114 watts (21kw) per day based on your 72,000/day quote.

21kw per day for 150 days (5 months x30 days) = 3150 kw of electric heat (except electric is nearly 100 efficient, BUT:

Your heater is gas powered, so the kw you're measuring is for the fan.
Streetbu is on the right track...how much gas are you using?

 

[Bert_]

I think he's using the kill-a-watt to calculate the heater's total run time. You could use that number to estimate gas usage. A little over $100 for the winter depending on what you pay for natural gas

I could be way off, post is not clear at all.

 

[2011laramie]

I was using the monitor to see how often the fan runs.

We pay little over $3 a GJ if i recall.

My math came out around 10 bucks a month in gas charges.

45000btu x2hr a day x 30 days = 2.7 million btu a month.
1 gj has 948000 btu in it

2700000/948000 =2.85GJ of gas used a month.

 

[laser3kw]

interesting
that is great to put some numbers to an otherwise guess.
It is somewhat of a debate on "how big of a heater do I need?"
If a garage is well insulated, you can use a 45k to heat a 1200sq ft if your intent is to just keep the cold off.

 

[D45]

These heaters draw less than 5 amps