3 car garage heater suggestion?

What's odd about being safe and healthy ? One's health shouldn't be measured by saving a bit in cost. Every non vented combustion heater carries health / safety warnings. The warnings are based on reality. Advocating for a totally safe heat source is not building a new structure. Personal experience guides my comments, one can make better choices, if they want to.

 

Hi Kurt,
Retrofitting an existing slab, with a low-voltage radiant mat heating system, can be relatively easy and surprisingly efficient. A layer of thinset or polymer portland is applied before and after the "mat" is positioned and finished with tile (if desired), raising the floor height only 1 - 1.5 inches.

A hot liquid (I would not use water in a garage) in-floor radiant, IMO would be the best choice and best included in the original build, but hot liquid baseboard radiators can also be added after the fact. While electric or gas baseboard systems are more efficient than hot forced air heating methods, heating the slab, is more efficient yet.

Radiator systems heat up quicker than floor systems, but when you heat the slab, the temps are a lot more consistent, since you are heating "rock" rather than air. You can leave the garage thermostat set just above freezing most of the time and if you plan to be in the garage for an extended period, go out an hour or two before and turn the t-stat up, then turning it down again, an hour before you quit.

Air is an insulator, not the most effective way to transmit heat.

Heat rises, what better heat source than the floor?

Talk to heating contractors that are experienced with and offer all types of systems.

Regards,
Bill

 

hey Bill - that 'mat' heating system sounds interesting. Can imagine though that covering the whole 800sq ft would cost much more than the $5k I was quoted for an epoxy coating... When Cheesy mentioned "in-floor" I envisioned a system with piping buried in the concrete slab.

I did have a heating specialist come out, take measurements and provide a quote. He recommended a 50k BTU, 20' tube (NG, infrared) mounted near the large garage door. No additional outside venting. Installed for only $3400. I can buy the unit they would install (Reznor VR50-20) for <$1100, and can't imagine installation taking more than a few hours tops. Sorry but I can buy piping, hangers and thread sealant and spend a few hours doing it myself. Yes Cheesy, I have a spray bottle with soapy water

Anyway, if the the 25k BTU unit doesn't work to my satisfaction (maintain 40F+ on the coldest days) then I'm only out $300. I've got one of these as well, don't tell Cheesy

 

The flame-in-tube infra-red systems are quite good, but the object of them, is to heat the concrete below. They work well, as long as nothing obstructs the path between the tube and the floor. I am not sure, that non-vented would be my choice, but then you also have the efficiency loss from using heated inside air for combustion and sending it out the vent, unless you draw outside air for the burn.

If properly calculated and sized, some of the low-voltage mat systems consume from 4 to 6 watts per foot.

Although there are a number of types/brands, here are some links to related info,

http://www.warmfloor.com/
http://www.greenbuildingtalk.com/Forums/tabid/53/aff/12/aft/29963/afv/topic/Default.aspx
http://www.diychatroom.com/blogs/electric-radiant-floor-heat-51/

 

Heating the floor is an excellent way to heat the garage - in my opinion the best.
There is no ignition source (who of us had not had gas spills?), and the heat is even.

Certainly there are retrofit options as well, as described above.
However, with a slab that has not been insulated, a LOT of the heat will be lost to the ground below the slab.

Before a new slab that will contain heating elements is poured, insulation panels are laid out over the crushed / compacted stone to minimize this heat loss.

I am faced with the same situation, as I have a lot of work to do on my car this winter, and the garage is only insulated. I use two plug-in radiant heaters, which take about two hours to heat the garage to about 55 deg F.

My garage floor is in rough shape (and I have a boiler), so when I pour a new floor next year I will add radiant heat piping to the new slab (after insulating of course). I will also add two layers of the thickest vapor barrier I can find, as my floor turns brown and gets wet when it rains outside!

 

You may not want to insulate the to the ground too effectively, or you'll lose the side benefit of stopping the frost heaving that causes garage floors to crack. This could be problematic with hot-liquid heat in the floor. BTW, propylene glycol and some other more efficient and non-freezing heating fluids are available, just in case the system goes cold for some reason.

Insulate outside the footings and cover w/soil, by all means, just think about how much you want to insulate under the slab. Once you get the ground underneath warm, it will stay fairly warm, not that much loss. Most of the heat rises, but through contact it will lose some of it's heat through the rock and soil beneath, which in my thoughts is a plus.

Just my thoughts.

 

i highly recommend a natural gas, vented heater such at this one:
http://www.shophmac.com/modine-hd45.html
these can be installed for around $500.00, depending upon how long of a gas line you need.
they are ceiling mounted, low profile and cost little to run.
i have had a similar design in three different homes, all worked flawlessly.
regardless of what system you choose, you must have a well insulated garage.
a wood or composite garage door is better than a metal door for insulation purposes.

 

We have a 2000 sq ft garage with a single ceiling-mounted Modine gas unit that the previous owner had installed. It's too high up (12 ft) for me to read the BTU rating but it does a really nice job of keeping the whole space heated. We normally keep it set to around 45-50F and raise it to 65 when we'll be out there. It heats up surprisingly quickly. The kids have one of those inflatable bouncy castles in the garage that they love to play in (and the adults have a ping pong "arena") so we spend a fair amount of time out there. I suppose a floor unit would be more efficient due to the height of the ceiling but I don't think I want to go fixing a problem that really isn't a problem at this point.

 

Can I ask why you need a heater in your garage?

Until the temps get to -40 degrees*, the coolant and battery will be just fine. So there is no particular need to rent a storage place to overwinter the car.

(*) at -40 degrees F=C so it doesn't mater what denomination the scale in in.

 

this thread makes me miss the heated garage my parents used to have before they added a bunch of rooms to their house used to ride my bike in it during the winter etc haha

 

that is what is in my garage, a Hot Dawg. About 10 years old now and still working great.

 

I am in S. Calif. and I have a heater in my garage, it makes a pleasant place to work in on the weekends.

 

Good that it all works out for you. Explain to me natural gas furnace has to exit the peak of the roof in your area? The newer high efficient gas furnace can exit thru the wall around here.

 

Looks like a spam post. The exact same post was posted here and here.

 

I see, 1st post! What is the benefit to do this?

 

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Many thanks,
Andrew.