Help me size a heater for this garage

[overdriv]

I am building onto my garage. Going to heat the new edition with radiant under the slab. The old garage is heated with a ceiling mounted propane heater that does a very good job.

I plan to remove the wall between the two. Also I plan to have some kind of curtain separating the two to keep the dirt out of the old garage which will be cleaned up and used for parking our car and pickup.

I'm hoping the radiant heat in the new part will warm the old garage enough to finally eliminate the propane heater.

Both parts are insulated, new part better than old. Both doors are insulated.

The new part will mainly be for working on the hot rods.

Using the simple heat loss calculator in another thread, I figured the heat loss on both sections and came up with 29314 BTUHS.

How big of NG water heater would I need?

 

[MikeLawrence]

I am building onto my garage. Going to heat the new edition with radiant under the slab. The old garage is heated with a ceiling mounted propane heater that does a very good job.

I plan to remove the wall between the two. Also I plan to have some kind of curtain separating the two to keep the dirt out of the old garage which will be cleaned up and used for parking our car and pickup.

I'm hoping the radiant heat in the new part will warm the old garage enough to finally eliminate the propane heater.

Both parts are insulated, new part better than old. Both doors are insulated.

The new part will mainly be for working on the hot rods.

Using the simple heat loss calculator in another thread, I figured the heat loss on both sections and came up with 29314 BTUHS.

How big of NG water heater would I need?

My gut (and a little napkin math) says something more like 60k would be right if you're trying to heat up the WHOLE space (both sides) but I'd be looking for someone with some first hand experience of a setup like this.

Just a guess, but (especially if you have it curtained off) I figure the old part of the garage is going to be at least 15 degrees colder than the new when it's bad out. Then again given it's usage that may not be a problem at all.

Michael Lawrence, LISSCO
www.thruwalls.com

 

[overdriv]

My gut (and a little napkin math) says something more like 60k would be right if you're trying to heat up the WHOLE space (both sides) but I'd be looking for someone with some first hand experience of a setup like this.

Just a guess, but (especially if you have it curtained off) I figure the old part of the garage is going to be at least 15 degrees colder than the new when it's bad out. Then again given it's usage that may not be a problem at all.

Michael Lawrence, LISSCO
www.thruwalls.com

No it really wouldn't, as long as I can keep it above freezing. It will be used for access to the new part and parking only. Probably a little storage of my fishing/hunting equipment and the wife's gardening stuff.

Actually, no more than it takes to heat the old part now, I could leave the propane heat there for really cold weather.

 

[BTI]

Actually, no more than it takes to heat the old part now, I could leave the propane heat there for really cold weather.

Or add a radiator to your hydronics you are putting in the new section.
You could turn it on as needed.

BTI