Garage Heater

[R Clark]

Doug,

Here's a link to a BTU calculator I used when sizing my heater:

BTU Calculator

It will calculate based on total volume, factored for insulation quality and desired temp increase above outside temp.

For my shop size of 44' X 25' X 12', a temp increase over outside of 70 degrees and normal insulation, BTUs needed came out to a little over 77K.

I think your sizing for your described space looks to be about right according to that calculator, but you may want to play with the numbers to satisfy yourself.

Good luck on adding the heat.  You're gonna love it!

[CLETUS]

I went direct vent with my first one, but skipped it on this one..the kit was expensive, and i wasn't sure it was really worth it.

Since you've had both, can you expand on the differences you're seeing? 

I'm thinking of going to propane from a woodstove in my shop. I'm back and forth on vented or not...

[blackhat]

Fred is, I believe, referring to a sealed combustion unit as opposed to a unit that draws its combustion air from the space around it. They have a second, intake air pipe, directly connected to the unit in addition to the flue that removes combustion products. Personally, I would never consider an unvented  appliance for anything but short term use in a well ventilated space.

[fredhargis]

Fred is, I believe, referring to a sealed combustion unit as opposed to a unit that draws its combustion air from the space around it. They have a second, intake air pipe, directly connected to the unit in addition to the flue that removes combustion products. Personally, I would never consider an unvented  appliance for anything but short term use in a well ventilated space.

What he said^^^^^. Direct vent has a sealed (or semi sealed) combustion chamber. One big advantage (I guess) is that the fine dust doesn't settle on the electronics of the system. Some folks see the direct vent as a safety feature (no argument from me) since it prevents fumes, and dust from getting to the flame. Sterling claims it increase efficiency of the furnace, in their case the incoming air is heated slightly by the exhaust. But that increase is very minor, and I've decided if dust cooks my electronics, I'll just replace the furnace. But I am not a fan of unvented gas heat, I've had 2. While the odor itself was a problem, the moisture they generate was a bigger one. That said, there are folks who use them and love them...so if it works for them who am I to argue. They just aren't suitable to me.

[CLETUS]

 But I am not a fan of unvented gas heat, I've had 2. While the odor itself was a problem, the moisture they generate was a bigger one. That said, there are folks who use them and love them...so if it works for them who am I to argue. They just aren't suitable to me.

Ah, ok. I thought I finally found someone that thought unvented was OK...

[ajkoontz]

Ah, ok. I thought I finally found someone that thought unvented was OK...

I have an unvented NG unit like this in my 24x24x10 attached garage. It's fairly well insulated in the walls and ceiling, but not really well sealed so I think that helps keep the place ventilated. Condensation is a concern, but nothing like the humidity in the summer. Runs me about $1/ day to keep garage at ~68F here in central IN in the winter. No complaints from me on this unit. When it goes out, I'll buy another non-vented just like it.

[Tapper]

Doug,

Here's a link to a BTU calculator I used when sizing my heater:

BTU Calculator

It will calculate based on total volume, factored for insulation quality and desired temp increase above outside temp.

For my shop size of 44' X 25' X 12', a temp increase over outside of 70 degrees and normal insulation, BTUs needed came out to a little over 77K.

I think your sizing for your described space looks to be about right according to that calculator, but you may want to play with the numbers to satisfy yourself.

Good luck on adding the heat.  You're gonna love it!

Thanks for the calculator - looks like I'll be OK, assuming I'm interpreting the numbers correctly. Yes, I'm looking forward to getting this project done - way overdue! Thinking seriously about installing one of those "RaceDeck" floors also.

Doug

[daddo]

Man once asked me how he would know if his unvented gas space heater had used up all the oxygen in his room?  I told him the fire would go out. He said he'd keep an eye on it.