View Full Version : Garage heaters? Modine Hot Dawg? What have you got?

12-20-2010, 03:27 PM
We're at that time of year again when I am reminded that it gets too cold in my garage to do anything useful for more than a few minutes. I need HEAT!

The garage is 24x36, fully insulated walls and doors, 2" of dense foam under the concrete, all planned for the eventual installation of heat. I was thinking of using an Empire DV-55 wall furnace (55,000 BTU) with external vent because I have one in the other garage. It's set for 45 degrees from December to April. I had the propane service guy here today to take care of a minor problem with the wall furnace, and he recommended a Modine Hot Dawg. They come in various sizes, but a 60,000 BTU one would be OK. He mentioned that a wall furnace would need bollards in front of it to prevent a collision if I put the furnace on the back wall, maybe no bollards if on a side wall where a car can't hit it. My current wall furnace is on a side wall. The Modine Hot Dawg mounts from the ceiling, wouldn't have that issue. The Hot Dawg is also external vented and there's a model which brings in combustion air from outside the building.

Anyone have a Hot Dawg? Happy with it? What else do people use for propane heaters that don't vent into the garage?

12-20-2010, 04:32 PM
My garage has a old fuel oil furnace (see thread from last winter!) as well as a wood stove.

However, these units seems to be pretty popular in commercial garages/shops in this area:


The lab/shop I am working in the past couple of weeks has one and a former workplace did too. I've seen them elsewhere in various places too. Don't know how they compare price/performance/etc with that Modine unit.

Ernie Stoltzfus
12-20-2010, 04:57 PM
I have a Modine Hot Dawg heater in my garage, and have used it for the last 7 years.
It works great and have had no trouble at all with it.
The area that I heat is 24 X 26 ft with 8ft ceiling.

Bob Andrews
12-20-2010, 07:05 PM
When I built my garage in '85 I went with a ceiling-hung gas heater. Similar to the Hot Dawg but about double the size. Hang it, wire it, gas line in, thermostat wire, and it's done. Worked in there every day for 12 years and it was always great. When I painted a car in the winter I'd get everything ready to go, crank the heater till it was sweltering hot and shut it down. Even at 20 degrees there would be enough heat to finish and cure the paint overnight. My garage is 30x44 with 10' ceiling, completely insulated and paneled.

12-20-2010, 08:15 PM
A shame you didn't install PEX tubing when you poured the concrete. I will if I ever do.

12-20-2010, 08:21 PM
Sonny taunted me off all the salamander craze...
He told me to get a cheap propane torpedo heater and skip the kerosene soot laden heaters.
I have almost 3000 square foot to heat, and it is uninsulated, so keeping it shirtsleeve warm is out of the question.
Sonny suggested a small propane turbo type spot heater...
http://www.northerntool.com/shop/tools/product_200455387_200455387 (http://www.northerntool.com/shop/tools/product_200455387_200455387)

I have used this heater as a 'spot' heater for several weeks, and it has performed superbly.
Blows heat where I need it now...
Not the whole shop, which would be a pipe dream...
I snagged mine from Harbor Freight...

12-20-2010, 08:57 PM
I have a garage 24X24 with 8 ft high walls I have R19 insulation in the rafter and R13 and sheet styrofoam one inch thick on the side wall s of my garage. A friend of mine a couple of years ago put new electric heat in his house. I bought 16 ft of used base board electrical heat including a thermostat from him for $25.00. With a fan in the ceiling for circulation of the heat I can turn on the heaters and go to church and come home two hours later and it will be 60 degrees or better in the garage. Anything above 60's degrees in the garage is most comfortable working conditions for me. Even in the coldest winters the temperature in my garage new goes below 32 degrees.

In the summer with a 10,000 btu wall mounted ac unit and two box fans mounted from the ceiling I can maintain 72 degrees all day even if it is in the high 90's.

John S.

12-20-2010, 08:59 PM
I'm really focussed on those heaters that vent the burned propane gas (because that's what I have access to) to the outside of building so I don't get a buildup of water vapor in the garage. For sure, the "gravity vent" heaters are much cheaper, but burned gas just makes water and everything rusts. Both Modine and Reznor make two kinds of external-vented heaters: one type that uses the air in the building for combustion and another ("separated combustion") that takes in air from outside the building for combustion. They claim that the separated combustion units are more fuel efficient and are also correct when dust (e.g., sawdust or grinding dust) or corrosive fumes are in the air. The separated combustion units are about 60% more $$ than the other type, but the long-term savings might pay for that. Having read through the data sheets for the Modine HD/HDS and Reznor UDAP/UDAS products, I am suspicious that both brands come out of the same factory with only some minor styling differences - the dimensions are too similar! Modine and Reznor are completely separate companies, but the products are extremely similar.

I need to just bite the bullet, call the propane company, and have them put one in. I can always turn it off if it gets too expensive to run. What was the old quote? Something like, "The bitterness of poor quality is remembered long after the sweetness of low price is forgotten." [Ascribed to Aldo Gucci, but may be even older.]

12-20-2010, 09:02 PM
I'm using a Roberts-Gordon gas tube heater rated 35000 Btu in to heat a 1400 sq.ft. shop with 10' ceilings. The shop is 30x40' with a 10x20' adjoining section. The building is well insulated with R32+ in the ceiling and R22 in the walls with insulated vehicle doors front and back. The heater was originally a propane one but I had it converted to natural gas. The gas consumption is quite reasonable. I keep the shop temp. in the mid 60F's all winter. The added bonus to the tube heater is that it has a balanced flue and is recommended where explosive atmospheres may exist or occur.

12-20-2010, 09:05 PM
Even I have to admit that applying the CASO heating and cooling mantra is not without it's peril....
I know less every day...

I'm really focussed on those heaters that vent the burned propane gas (because that's what I have access to) to the outside of building so I don't get a buildup of water vapor in the garage.<snip>

12-20-2010, 09:20 PM

Don't use any unvented heaters in a well sealed environment. Here is my experience with both the unvented propane type and the propane Salamander style Jeff uses.

The unvented heater rated for interior use will rust the heck out of anything steel due to the moisture created buy combustion, secondly, as you reach the bottom of the propane tank you will smell the mercaptan used to add odor to the LPG, it must concentrate there. Lastly, if you paint or use organics in the shop, the odor of their thermal decomposition will drive you out.

I had one for three years and it finally became more than I could tolerate so I replaced it with a Williams 40K BTU vented propane wall furnace to heat my 16 X 40 insulated shop. I keep it at 40 deg at night and heat it to 55 deg when I work in it. I use about 150 gal of propane per season in Michigan.

As far as the Salamander style propane unit, it is not recommended for closed spaces. I use a 60K BTU propane unit to heat the 32 X 48 ft uninsulated portion of my pole barn, and after a few hours you will notice an acrid odor that is unpleasant at best. But it's better than 20 deg F at times.


12-20-2010, 09:21 PM
I have an unvented 30,000 btu propane heater in my 24'x24'x8' garage. It heats to 70 in less than a 1/2 hr. That's the good part. The bad part is the floor stays very cold! It's a monolithic poured floor. There is 27 yds of concrete in it because of the slope of my yard. Once it's cold, it stays that way!

Bob Andrews
12-20-2010, 09:44 PM
I'm really focussed on those heaters that vent the burned propane gas

Agreed. I didn't mention, that's what mine is. The one below looks similar to mine (as far as I can tell with one face-down picture):


As for in-floor heat, you bet I'd do it if I had it to do again. If I build the addition on my home shop I want I'll absolutely have it! The local heavy truck shop on my mail route has it; heats it with a waste-oil boiler. One you roll a creeper on it or sit and do brakes you are forever hooked!

12-21-2010, 09:00 AM
I changed from an unvented nat. gas to ceiling hung Mr. Heater Big Maxx and I love it. I heat just over 1000 sq. ft. with 10 ft. ceiling. Keeping it at about 45 doesn't cost much at all and it will heat the space up in about 15 minutes if I want to work out there. Thumbs down on the unvented unless you just plan to use it occasionally - too much water vapor.

12-21-2010, 09:27 AM
One of the fun parts to a forum is that you can comment on things that you know nothing or very little about. Another thing is that you can offer great suggestions on spending "other people's" money. With that in mind...here are my comments.

Since warm air rises, the suspended heaters require more fan power to circulate the heat to the floor and are probably less efficient. Where gasoline (as in car gas tanks) is stored, I would not be too excited about a heater that has pilot lights or as in electric heaters, red-hot heating elements.

That being said, I would prefer a heating system with a heat exchanger plenum where potential ignition sources are not exposed to gas or solvent vapors. Living in the south with short winters and little exposure to extended periods of freezing temperatures makes it difficult to truly understand the challenges some of you have to meet.

Yesterday, I fired up my torpedo kerosene heater for the first time in over a year. It worked fine after the smoke cleared as the wasp nest burned out!:rolleyes:

Ray Stewart
12-21-2010, 10:21 AM
When I lived in MI I installed a natural gas fired unit heater (with typical heat exchanger) to a pole barn...the entire unit set outside with only ducted return & supply into the barn. Wanted to be certain that the flame was removed/contained away from the area I was painting, stripping, sanding, grinding...etc. Now in KY and have an outdoor boiler which heats the house & hot water...lines also go to the barn and I have a F**d Ranger radiator built into a wood board cabinet with a box fan behind it...with a thermostat controlling the fan. A small ceiling fan to keep the heat down off the ceiling. Heating 26' x 40' x 14' ceiling no problem...with almost no insulation. Get all the wood I need free and burn about 6 full cord a year. These outdoor boilers are being ban in many parts of the country where there is dense population...not an issue where I live.

Skinnys Garage
12-21-2010, 11:37 AM
I decided to take the gas line, pilot/igniter and vent out of the equation. With hindsight being 20/20, I would have done things different on my own system, but this is what I ended up with.

It's an old electric hot water boiler from a two story house that my friend switched out for a new gas one. I have a pair of heat exchangers with fans mounted on the ceiling with insulated copper pipes connecting them through the attic.

If the garage hadn't already been built like yours, I would have floor heat. Once you get that slab of cement warmed up it's hard to beat, especially working on a car. I might modify my ceiling system someday with fin tubing in the garage connecting the exchangers.

My system is ancient, but the new electric boilers are very compact and you can just turn them off with no worries. My friends rural electric carrier hooked his up using an off peak box and gives him a great rate. With a few weeks of below zero temps mixed in, mine can cost me up to $100 a month to keep things above freezing in the winter months, like I said, it's ancient......


12-21-2010, 12:06 PM
Hey guys, after reading all the above posts, thought I would throw my version in too. Our house we built in Alabama was about 2700 sq. ft. in the living area, and 2300+ in the temp controlled basement. My wife and I are both VERY cold-natured, so we thought and investigated a lot of systems. I did not paint in the basement, but we did all other auto and other "hobby" jobs there. The system we settled on was simply a tube-type radiator hooked to our hot water heater with a 110 volt fan/thermostat/and pump to circulate the hot water, then blown thru conventional ductwork. Alabama is not as warm as some may think all the time, but with this simple system heating that much space,( house and basement), it was never chilly. An added advantage was the 110 volt works, so during our MANY power outages, a small sized generator was all we needed to keep going. We had a propane heater, (it could have as easily-tho' more costly-been electric) to supply the heat, and in a garage type setting, the heater could be out of the "work" area. This system is very reliable, warm, clean, and was much cheaper to use than any of the neighbors/relatives/friends in our area even with some having smaller houses. A regular ceiling fan kept all mold/mildew/smells like some basements have non-existent. Might be a system to consider. Noticed Ray Stewart above had about the same. Highly recommended, John

12-21-2010, 12:31 PM
Gary, you might want to look into propane-fired overhead infrared radiant heaters. Basically, they look like a long fluorescent lamp fixture with a length of 4" steel pipe replacing the tubes. Burner at one end, and a wall vent at the other. Pipe gets hot, but well short of red hot, and radiates heat on all below. Doesn't warm the air much, but warms the floors and all the contents of the room, humans included. You quite often see them used in service bays around here. Really nothing much more than a gas blowtorch fed into a long tube with a metal reflector above it. Not very noisy at all, and takes up zero floor or wall space.

In-floor heat is the way to go, though, if you are building.

Henry Votel
12-21-2010, 01:39 PM
Hi Gary,

My quonset is 22' x 40 and 11' high at the center. It is well insulated with iceynene foam. The concrete floor has 2" of foam under it. I have a 10' infrared heater on the ceiling 5' off the end where I do most of my work. It has a 10'+ clearance. It is a model designed for garages and lower ceilings. The dual exhaust pipe goes straight out the wall and it is also the makeup air intake pipe. I keep the quonset at 45° until I come out to work. The infrared warms objects and even in our recent cold spell of around 0° the temp ran from 45° up front to 42° at the rear. My unit is natural gas fired; propane adapters an option. My actual use gas for heating bill runs about $35-40 when it is cold outside in the coldest months; often less than $20. When I go into my shop I turn the temp control up and within 10 minutes I am in shirt sleeves with 65°±. I hung the unit myself and hooked it all up; relatively straight forward and easy.

Important to me in selecting the infrared unit was: 1) makeup air was from outside (I paint in my shop) , 2) No fan blowing air around (I paint in my shop), 3) No fuel exhaust/residuals in the air because (I paint in my shop) and do not want the problems associated with contaminating paint jobs, 5) The floor stays warm and drys itself, 6) operation is inexpensive, 6) if I open the door(s) the objects inside stay warm rather than all the warmed air escaping, 7) I don't get the cool down-heat up cycles that one get with forced air furnace thermostats. When i installed this unit 5 years ago I had about $750 into the whole job.

Here's the site I bought mine from, there are many other vendors: http://www.superiorradiant.com/Home.aspx

My 2¢

12-21-2010, 04:42 PM
Gordr, you just described what a Roberts-Gordon heater is! Mine works great and the floors are always warm as I leave the unit on 24-7. During normal southern Ontario winter weather, the unit runs for approx. 15 min. every 2 hours or so. Although they are designed to run continuously, if needed, such as in chicken coups, mine has never approached that in the coldest of sub-zero weather.

12-21-2010, 06:35 PM
What a great bunch of stories and details about garage heating! I can feel a lot more comfortable - should I say warmer? - about the choices knowing how it has worked out for other people. Thanks and Merry Christmas!

12-21-2010, 06:36 PM
I have a friend in Maryland who has a 25 car garage.
It has doors down two sides.
What he does to warm it is open those doors, turn on all the cars, let them all warm up, then turn them off and close the doors.
The residual heat from all the engine blocks, combined with the insulation of the walls and doors, keeps the place toasty warm for a few hours.
Not sure how well this would work with a smaller garage. Two or three engine blocks might not do the trick.

12-22-2010, 12:39 PM

Bob Andrews
12-22-2010, 04:17 PM
Gary, you might want to look into propane-fired overhead infrared radiant heaters.

Just to add, we have these in the auto shop. They cost a lot to run in a working shop with cars frequently in and out. Haven't been run in about 10 years since we went to a waste-oil furnace. We collect oil from oil changes all year, and burn most of it, about 800 gallons. Needs to be serviced once a year, about $250. I think it was around $3K new.

Skip Lackie
12-23-2010, 05:27 PM
One more vote for the wall/ceiling mounted Modine. I have a 25'x60' garage with a ten-year old Modine PV. I leave it on 44 degrees all winter unless I'm working in there. About 200 pounds of propane is enough to maintain that temperature all winter. It can warm it up to 55 degrees in about an hour, which is warm enough to work comfortably (unless I'm lying on the concrete floor!).