30,000 or 45,000 btu's

[lkg907]

I've decided to go with the Modine Hot Dawg. Now the decision is how big.
This is going to be a super-insulated building of SIPs construction. R26 walls with R-50 in the roof. 900 sq feet with 10.5' ceilings. (2) 9' garage doors and not many windows. This is in E. Washington, where a zero degree day is uncommon. If you do get to zero or below, it doesn't last very long. I'm comfortable with staying out of the shop for a few days, if need be.
I've run the calculations as best that I can. But maybe some of you folks with similar weather can just tell me what you've got?? Calculations are one thing, reality is another. Thanks.

 

[sneezer41]

Why such a low tech heater in such a high tech building?

Do a heatloss calc and you will know the answer

 

[sneezer41]

seems to work:


http://www.builditsolar.com/References/Calculators/HeatLoss/HeatLoss.htm

 

[UnSub45]

Another thing to consider is how fast do you want to warm up the shop. Is this a weekend only type garage? If so you probably want the ability to bring the garage up from 30 up to 60-65 in a short amount of time. Even if the 30k unit can heat the garage, the 45k will bring it up to temp faster.

 

[Red'n'WhiteRebel]

If you're having it installed by a professional they should do a heat loss calc. for you.

 

[Bencrx91]

I have a REZNOR heater, garage 20 x 26 x 9.5ft high.
I have a 45 000 btu Natural Gas. Works well. Not that expensive to run.
It gets pretty cold here in Québec.

I would go with the 45K btu, when you need to crank it up, it bring the heat up quickly.
I find that leaving the garage at 10 oC all winter is more efficient than trying to heat it up on week end only. Cost a bit more, but not that much, and the concrete slab is not as cold.

First year, I would heat it on week end only.
Second year, I would leave it at like 4 oC
This year I left it at 10 oC and I will continue to do that now.
It makes your tools more enjoyable to work with.

Another suggestion : Try to get the version that take the outside air for combustion.
It's just more efficient, but cost a bit more.

Hope it help!