Heating my garage

During the winter I would like to work on some of my small tractor/farm projects in the garage. One wall is shared with the house. The ceiling and walls are insulated. The ceiling is 8 foot from the floor. Anyone have any experience with these natural gas units - Mister Heater brand or the Modine Hot Dawg brand? I think 50,000 BTU's is adequate. I got a quote from a heating/plumbing company and it was $4000. I don't think I want to spend $4000 to heat my garage. The was for a 50,000 BTU furnace, flue, and running the gas. I will get some other bids. What about the 5000 or 7500 watt electic hanging heaters? I do have a primary fuse panel in the garage. Would I be happy with one of them and not have to worry about a flue or running a gas line? Also, I do not want to burn wood. Any ideas appreciated.

Why not borrow from the house by installing a duct and a fan to help pull the heat,, ?

We put a ventless 30k BTU natural gas heater in our garage in IL. Worked great, just set on one of the lowest settings. No need for vent or electrical wiring. I think it helped though that we had a ceiling fan in the garage that helped circulate the warmed air. Not sure Id do a ventless in a well sealed living space, but I figured the garage had enough leaks and door openings to vent the slight amount of moisture produced by the heater. It was about $250.

I agree with Oldgent a easy solution if the house furnace can deal with the added load without running full time. a competent HVAC analysis can make the decision accurately. There is also nothing wrong with electric heat other than expense. If not continuous it will be worth it. Jim

I got a propane furnace from a travel trailer. I set it up, so it vents and exhausts through
a window. It takes a while to warm up the shop (24 x 24) but as I'm not out there all day every day, in the bitter cold,
it's not a problem. The house is Natural gas, so I have a couple 25 or 30-pound propane bottles I use on the furnace.
The one I got is 12 or 120 volts, so all I had to do was plug it in. I even put a thermostat on it.
Anyway, that worked for me.

Menards sell a very reasonable priced ceiling hang gas heater, works great in my shop with 8' ceiling 32'x54'. Warms up quickly & uses very little gas.

look into the electric baseboard heat. my 12 unit rental was heated with these. no smell, no gas fumes, no dust. cheap install too.
poke here

I have a 5000 watt electric heater in my well insulated 1500 sq ft with 10 foot ceiling garage. It keeps it over 40* in northern South Dakota on the lowest setting. I have it wired to the heat meter which is at a lower kWh rate.

I repurposed the electric heat portion of the central unit from the house when I replaced it with a heat pump system.

Cut it down to size so it was as compact as possible, hung it from the ceiling.

I had easy access to the electric panel, probably cost me $50 for a breaker and the wire. Works great!

You can find those units cheap or free, the HVAC installers scrap them all the time!

I have seen that furnace at Menards. What is your ceiling height? The Hot Dawg brand says a minimum of 8 foot from floor to the bottom of the furnace.

Remeasured my ceiling is 10'

I did something similar 25 years ago in a lightly insulated three car attached garage. The cost to install a 40,000 BTU vented natural gas ceiling furnace with 80 feet of gas line was about $1600 at that time. It was sized for a modest 40 degree heat rise over the outside temperature. Installation, chimney, and gas line was well over half the cost. Going to a larger unit would have required a larger diameter gas line. For me, adding more ceiling insulation was cheaper than upgrading to a larger furnace. The cold concrete floor still absorbed a lot of heat fast. Your $4000 quote sounds like it is in the ballpark.

Electric heat will generate 3.4 BTU per watt. A 5000 watt heater will only produce 17,000 BTU, a 7500 watt unit will produce 25,500 BTU.

I have attached single garage, well insulated, gas baseboard heat, & added a zone valve to my boiler & run baseboard heating units around garage walls. It cost me an extra $25-$35 extra a month. I leave thermostat @ 60 degrees all winter months.

I live in Illinois too and have a ventless lp heater like you describe in my 600 sq ft work shop. It is insulated with 8 ft ceilings and I only run it when I'm in the shop. Takes it @ 1 hr to raise the temp to a comfortable working temp. I wouldn't be afraid to use one in the garage at all, remember, they have ventless fireplaces for living space.

A lot of opinions have already been expressed. Several key points have not been addressed (yet).

You DO NOT want to share ductwork in your garage with ductwork in your house. If your home heating system is large enough, it doesn't seem like a bad idea to use the excess capacity to heat your garage. The problem is in the cold air return system. Codes (and common sense) don't allow returning air from the garage with the possibility of all sorts of fumes into the home living area.

When comparing gas and electric heaters you need to realize that gas heaters are rated at INPUT btu. The brands you mentioned are about 80% efficient, so a 50,000 btu gas heater will supply about 40,000 btu of heat. A 5,000-watt electric heater will supply about 17,000 btu of heat since electric resistance heat is nearly 100% efficient.

From my own experience in central Indiana, I have a three-car garage with 10' ceilings. It has a ceiling hung gas heater of about 100,000 btu. I rarely use the heater, but it will heat up the garage to comfortable temperature in just a few minutes when I want to work in the garage. I had a neighbor who built a huge detached garage some years back. He walled off a 16' x 22' work room on one end. In the winter he kept a $15 1500 watt electric heater going to keep things from freezing. When he wanted to work in the winter, he plugged in one or two additional heaters a few hours before he intended to spend the day working. That solution worked fine for him.
You haven't mentioned the size of your garage, how often you will want it heated, your location/climate, and other factors that would influence your heat load. The best garage doors aren't that well insulated or sealed. Heat loss is greater if they are opened frequently.

You haven't mentioned whether your current gas and/or electric systems have enough excess capacity to supply heat to your garage.

My 2 car attached garage stays around 50. The thermostat is set below 50.



Spend your money on insulation.

I warm my garage with a 1500 watt baseboard heater.
It has 10 ft walls. The garage is insulated like its living space.

My BIL has his walls foamed before drywalling.
He foamed his pole barn too. Foam is the way to go, just cover it. Foam is not fireproof.

Put your $5000 in insulation, thermopane windows and insulated garage doors. My attic has 18 inches of fiberglass. My walls have over an R20 rating.

1000 watts = 3412 BTU's
5000 watts = 17,060 BTU's
7500 watts = 25,590 BTU's


Energy efficiency is the only way to go.
The cost of energy is only going up..

My shop is 2,000 square feet with 17 ft ceiling. I heated it last year for under $500.00 on propane. Installation cost was negligible. Got your attention yet? I heat an inner room which is 16x22x10 usually to 60 degrees. this room is insulated, and the heat that comes out into the main part keeps the large area above 40 degrees unless the outdoor temp drops below 10 degrees. The heater is a non-vented catalytic wall mount propane unit. I keep it set at 50 degrees, so that the room heats up quickly to 60 when I go in to work. The unit takes up virtually no space which would be very advantageous in a garage.

We have a Mr Heater Nat gas unit hanging from the ceiling, I think 45,000 btu. It has been running fine for 12 years, I had a service man look at it this fall and he said it looked good to go another 12. I bought it at Lowes, the vent pipe at a local hardware store. I did all the installation myself, I know it was under $600 completely done.

If it was me the first thing I would do is to install an insulated ceiling and insulate the side walls and make sure the door isn't leaking too much cold air in. Possibly put insulation panels on the door if not a good insulated door.

The ones you listed are good. I put A lightly used furnace that was 80% in. 90% and above need a freeze proof drain if you find one of those. My furnace cost 150$ and my time to install as the vent was already there. I know I need better insulation in the ceiling after the first real heavy use in 10 degree weather.

(quoted from post at 05:54:53 10/31/22) If it was me the first thing I would do is to install an insulated ceiling and insulate the side walls and make sure the door isn't leaking too much cold air in. Possibly put insulation panels on the door if not a good insulated door.

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Tom, he told us that his garage is insulated.

I have had 2 HotDawg heaters for 15+ years. 75,000 btu in my 24 X 30 shop that has minimal insulation R4. and a 50,000 btu unit in my attached garage 22X22 with a 10' ceiling. It is insulated and drywalled. I live in Ohio and these thing keep the area t-shirt warn in the winter. I only turn them on when I want to work and it is warm in about 10-15 minutes.

Your price seems a bit high but I am certain the gas line and flue are part of that. Sometimes that is quite complicated. They work great though.

(quoted from post at 21:56:33 10/30/22) Why not borrow from the house by installing a duct and a fan to help pull the heat,, ?

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Extremely unsafe, and against code in any jurisdiction that I am aware of. Ductwork leaves a direct path for fire, fumes, smoke, CO,.......... to enter the home. Never do it this way!!!!!!!!

I have a MR. Heater Big Maxx I think is the name of it ? It is a hanging LP with a power vent. Had it several years now and has been fine.

I installed a 45,000 BTU natural gas heater in my 25x30 garage a year ago. I hung the furnace and installed the vent myself. Had 30 feet of gas line trenched in and run to the furnace by the HVAC guy. Garage is open ceiling and fully insulated I can keep it 60 degrees without any trouble, all for less than 1,200 dollars. I know prices very but your quote seems high.

Spend your money for some windex for that clock LOL

4800W milk house heater is 16,000btu which ain t shabby .

I use mostly 20# tank mounted radiant heaters. Heats me very economically, follows me around where I am working, not the whole place, heating wasted space and paying high utility bills. But its your money!!!!!!!