Hot Dawg Garage Heater.

I just installed a Modine Hot Dawg Garage Heater couple days ago and am a bit dissapointed in the amount of heat it give off. It's a 45,000 btu unit installed at 9.5' high to the bottom of the unit and position in the corner of the garage angled at a 45 degree so it points to the center of the garage. I understand that the amount of drafts will effect how quickly the garage heats up but here are a few points.

Garage is 380 sq. ft.
Outdoor temperature is 33 degrees.
Double wood garage door.
open celing in that it's not drywalled.
Garage inside temperature 45 degrees.
Metal insulated side door.
Walls are insulated with R12 fiberglass bat and covered with drywall.
It's the natural gas unit.
Rated at 80% efficient.
Outlet Velocity (CFM) 749
Air Temp. Rise (°F) 46
Heat Throw (ft.) 27

When the heater is up and running it takes approximately 4.5 minutes to raise the temperature 1 degree. Therefore to go from 45 to 60 it takes over an hour. Regardless of how I position the baffles on the front it doesn't seem to make a difference. After the unit has been running for about 20 minutes I touched the front baffles. and it wasn't to hot to touch with bare hands. The rating of this unit is rated for a 2 - 2 1/2 Car Garage and I barely have a 2 car garage so it's somewhat over sized.

Any share your experience with this unit in these types of tempertures.

P/owner had a gas whole house furnace in the garage...about 380' of floor space, BUT had only a ~8' ceiling sheetrocked in....I forget if it was insulated up there or not, but it was in the walls....wood overhead door...

it was comfy in about 10 minits or less....from sub zero outside....

that's about all I can say.....I forget the BTU rating on the unit...I want to say something like 140,ooo but don't quote that....

it was set for propane, but I ran a gas line from the house to it and changed to nat gas....

:amazed:

Put 12" fiberglass batts in the ceiling and quit heating the roof, your garage will warm up much faster and hold the heat much longer, leaving more $$ in your wallet to spend on your vette.

If you're trying to heat a cold garage, you have to heat the mass of the garage before it will feel warm. Your house furnace is running (off & on) 24 hours a day and so the mass of the house is not as cold, even if the air inside is cold (what the thermostat thermometer says) so it does not have to heat the entire mass of the house up each time, just the air. It will take several hours to heat your cold garage to a comfortable level, but if you then leave it going all the time, it won't take so long. The bitch is, do you want to have your garage heated well 24 hours a day, or just heat it up when you feel like going out there?
And yeah, most of the heat is going straight out the uninsulated roof.

Remember, insulation does not create heat, it only slows its loss. If you insulate your water pipes but don't keep them warm, all that means is that they will freeze up & burst at 5am on Sunday instead of 10 am on Saturday.

I fire up the wood stove in my detached garage first thing on a 30* morning and then go have my breakfast and a cup of coffee. That will break the chill. Then I go out & stoke it up again, go back in the house and read the paper. In a couple hours, I can go out and start working. After another hour or so, say around 10 or 11 am on a really cold winter day, or earlier if it's not quite so cold out, it's getting nicely comfortable. If I keep the stove stocked up, by later in the afternoon, I'm down to a t-shirt & bandana around my head. Next morning, after choking down the stove but keeping it stoked thru the evening so it will burn low into the night, it only takes an hour or less to come back up to comfortable warmth when I fire it back up again.

You need a ceiling even if its only 1/2" drywall. Your pulling cold air from 9.5"up then shoving warm air down and it rises back up into the rafters.
If you could work in the rafters you would be good but you can't.
If you could set the heater on the floor so some of the cold air on the floor could cycle through the heater it would be better but then the heater would be sucking any fuel fumes through it (fire),if it was electric you could do this.
If a ceiling is out of the question you could position the heater so you work in the path of the airflow or at least heat something with the airflow.Shoot the air inside a car so the car heats up before going out the roof.

mrvette said:

P/owner had a gas whole house furnace in the garage...about 380' of floor space, BUT had only a ~8' ceiling sheetrocked in....I forget if it was insulated up there or not, but it was in the walls....wood overhead door...
it was comfy in about 10 minits or less....from sub zero outside....

Click to expand...

These garage heaters are not quite a whole house heater but then again that's what there made for.......to heat a garage.

Ozzy said:

Put 12" fiberglass batts in the ceiling and quit heating the roof, your garage will warm up much faster and hold the heat much longer, leaving more $$ in your wallet to spend on your vette.

Click to expand...

I can't insulate the ceiling since I can't get up there, it's so filled with storage material I can't walk up there, so that's not an option.

JPhil said:

If you're trying to heat a cold garage, you have to heat the mass of the garage before it will feel warm. It will take several hours to heat your cold garage to a comfortable level, but if you then leave it going all the time, it won't take so long. The bitch is, do you want to have your garage heated well 24 hours a day, or just heat it up when you feel like going out there?

Click to expand...

Talking to owners that have the same unit and a larger garage they told me, that they turned on the unit, made themselves a coffee and by the time they walked into the garage it was 70 degrees. Not so in my case.

DWncchs said:

If a ceiling is out of the question you could position the heater so you work in the path of the airflow or at least heat something with the airflow.Shoot the air inside a car so the car heats up before going out the roof.

Click to expand...

I can put my hand 1" away from the front blower when it's running full and it's not hot enough that I have to remove my hand for fear of burning it. For some reason it's doesn't seem to be running hot enough. As it stands now, I'm dissapointed in the amount of heat it gives off.

If you can hold your hand in front of it without burning there is something wrong. Go here http://www.garagejournal.com/forum/forumdisplay.php?f=26 they will be able to answer anything you ask about that heater. Its a cool site for anything garage related too.

I did a search and couldn't find any similar issues relating to mine and I'd have to join first in order to post my question so I'll hold off till I hear from the wise on this forum.
I was surprised there wasn't more heat when I placed my hand if front of the unit either but then again, the garage was at 35 degrees and my hand were pretty cold after helping the gas fitter.

Is it rated for propane or Nat Gas?

I'm not saying your heater is doing the best it can do but I don't think the air temp coming out of the heater burning your hand is an accurate check. It seems to me 180 is hot to the mouth and 140ish is hot to the hand. I've never checked the outlet temp of my furnace but it would have to be effected drastically by the inlet temp.
OK now I'm going to talk straight out of my ass because I don't know BUT looking at the stats you posted above I see a temp rise stat. "46 degrees."
Does this mean you take the inlet temp and add it to the rise stat
I think you said the garage was 35 plus the temp rise. 35+46=81* outlet temp? Where are the furnace guys ???
My electric "Dayton" heater won't burn my hand. I'll check the outlet temp for you but not sure gas to electric is a fair comparison.

edit- OK took some temp readings in my garage.
Air temp in the garage was 32
With heater running for 5 min I put my hand 1/4" from directional blades and the air was luke warm.
Shooting my gun in and hitting the metal thingys inside the gun read 440
The directional blade in the center pointed down of the opening read 160,the others read about 95
I could easily grab all blades except the center one and if I grabbed it and released a couple times I could hold onto it and after holding the temp read 120.
Hope that helps.
It would take several hours for my garage to come up to 60 and I have drywall all the way around and 16" insulation above the drywall ceiling and my garage floor floats on styrofoam.

big2bird said:

Is it rated for propane or Nat Gas?

Click to expand...

Natural Gas

DWncchs said:

I see a temp rise stat. "46 degrees."
Does this mean you take the inlet temp and add it to the rise stat
I think you said the garage was 35 plus the temp rise. 35+46=81* outlet temp? Where are the furnace guys ???
My electric "Dayton" heater won't burn my hand. I'll check the outlet temp for you but not sure gas to electric is a fair comparison.

Click to expand...

The inside garage air temperature was at 45 degrees F and it took over an hour for the garage heater to get the inside garage temperture up 15 degrees to 60F,therefore if I wanted the garage to go to room temperature at around 70 degrees then it would take close to 2 hrs. I though that was a long time in an enclosed garage.