Unheated garage

Hilly

I had a co-worker ask at the office today about his heating. He says that it is hard to keep the heat upstairs comfortable (well it takes a long time) because the master is over the unheated garage.
1) run a new heater to the garage on its own zone and run it 14-16*.
2) run a heater down off the top floor zone so that when rooms want heat the garage heats up to
3) add more element to the top floor to overcome the proper heat loss.

Just trying to keep it simple for him to make the bedrooms a little more comfortable. I'm going to go over later and have a look around. I'm sure all his fins could use a good brushing that'll help too.

hot_rod

Insulate between the garage and bedroom better?

Zman

4) Perform a heat loss calc and insulate the floor between the garage and house.

Hilly

It is insulated already. He is pulling down the ceiling near the front and back so that he can do a better job of insulating the headers and sealing them off. The mech room is next to the garage and he would like heat out there for future workshop but doesn't want it cutting all the time.

New in for:
He does have access to a half dozen cast rads so I am going to utilize whatever works with the heat loss and run it back to the boiler. It's just a matter of how to best set it up for his needs and budget. Aren't favours wonderful.

SWEI

Are the garage doors insulated? Walls?

Hilly

currently two insulated garage walls plus ceiling. Garage door is brand new R-15. It's a small 23'x12'x7' with one window. I'll get the HL sorted after, but it's not much. He bought the house only in the last little while so I also told him to pull all the fin-tub casings and vacuum out the fins, as that would be a starting point to getting more efficient heat upstairs.

Gordy

Rooms over unconditioned spaces are a SOB no matter what. I would condition the garage area. No matter what you do to add more heat to space above the garage the floor over garage will be a heat sink.

Builders should stay away from that design along with cantilevered bump outs.

Abracadabra

Gordy said:

Rooms over unconditioned spaces are a SOB no matter what. I would condition the garage area. No matter what you do to add more heat to space above the garage the floor over garage will be a heat sink.

Builders should stay away from that design along with cantilevered bump outs.

+1 This. Had a customer who had living space over a 3-car garage. All insulation was closed cell spray foam which gives you crazy high R values. Floor were 2x12", walls of garage were 2x6 all closed cell foam. scorched air heat. Very tight new construction. Ended up adding zone dampers and zoning that area seperately to give the space more heat.

SWEI

Passive solar garage, anyone?

Gordy

Facing S.E, glass garage doors. Or evac tube solar panels.

SWEI

South facing windows with proper overhangs will work from the side, back or even the doors (though that can take a bit of work with the door manufacturer, particularly for roll-up doors.)

IMO it's worth the effort. Really makes a huge difference in the usability of a garage or shop, with zero OpEx. You don't need a whole lot of solar gain to maintain ~50°F interior temps in many parts of the country, but you do need insulation -- and some careful attention to weatherstripping.

Works great on chicken coops, too.

Tom_133

I couldn't agree more with Gordy! I have lived in two different spaces above garages and they sucked. No matter what when my feet hit the floor I knew roughly the outdoor temp. When it was really cold my floor was below 50! That space only had a gas fireplace though. Inherently when you build above unconditioned space like a garage on a slab you get colder rooms. My theory was always insulate the best you can to isolate your living space and unconditioned space and use a warmboard, or similar to heat the floor.

Hilly

I got swamped at work. This project is for the middle of November. So I appreciate all the responses and apologize for not being involved in my own thread. I was thinking for simplicity and meeting the owners request. Could I take a branch off downstream of the bedroom zone valve. Then run the line to the heater and back to the return. I would put a thermostatic valve on the heater so he can set it to a mid range comfort level and it won't run when he's not concerned about heat upstairs. I agree that he should make it a full conditioned garaged but people often want what they want.

Hilly

Heatloss for 70* design for the garage would be approx 10866 BTU/Hr.
There are three Cast Iron heaters available with appox outputs at current boiler setting of 180/160.
1) 1600
2) 4000
3) 7600
I was thinking about using heaters 2 and 3. Would piping them in series since it is 2 heaters be okay? Or should I pipe them in either reverse return or homerun them. It's all relatively close to the mech room. Less than 15' so material is not a concern.

It's quite a small load but it might even be less because the exposed walls are probably 50% underground due to the lot grading.

Gordy

I would figure for 55-60 anything to relieve some load off upper floor unless owner wants to have it warmer.

Hilly

So two of the heaters will be needed whether I go 50 or 70* room temps. Since the max total load is 12K would it be reasonable to pipe those cast iron heaters in series? Or would you do a parallel direct (or reverse) return?