Heater selection

[ebg338]

After a lot of reading on this forum, research and doing a heat loss calculation, I'm thinking to go with a Modine Hot Dawg 75,000 btu (nat gas) for my garage.

My garage is...
30 wide, 35 deep, 15 foot ceiling. Windows are single pane, no storms. Walls and ceiling currently have no insulation (2x6 walls). Entry door is standard size and insulated, two 10 x 10 insulated garage doors. I do anticipate insulating/drywalling the whole thing but that will take some time so I wanted to go a bit higher on the btu's than i might otherwise and I'd like to be able to heat it pretty quickly. Does this sound reasonable size wise? Also, seems like the brand is a good choice - wanted American made and considered Reznor as well. Appreciate any feedback.

Thanks

 

[Jackfre]

Don’t go over a 50. You go with a 75 and you are nothing but oversized. Can you flash it? Sure, but that is not what yo want to do. A 50 is oversized for that space, and btw, are you in Minot or Miami? The 50 is big enough and won’t be ridiculous once you take a little time to insulate and bring the load down. I don’t know if you have ever lived with a way to large a heater, but compromise a bit and you will in the long run be happier and more comfortable.

 

[PoorUB]

I agree with the above. Once you get it finished up, 30,000 BTU will heat it. 75K is way overkill.

 

[toyotadriver]

Do you plan to heat it all the time? Or just when you go out there to work? What climate are you in?

 

[gmcgeo]

After a lot of reading on this forum, research and doing a heat loss calculation, I'm thinking to go with a Modine Hot Dawg 75,000 btu (nat gas) for my garage.

My garage is...
30 wide, 35 deep, 15 foot ceiling. Windows are single pane, no storms. Walls and ceiling currently have no insulation (2x6 walls). Entry door is standard size and insulated, two 10 x 10 insulated garage doors. I do anticipate insulating/drywalling the whole thing but that will take some time so I wanted to go a bit higher on the btu's than i might otherwise and I'd like to be able to heat it pretty quickly. Does this sound reasonable size wise? Also, seems like the brand is a good choice - wanted American made and considered Reznor as well. Appreciate any feedback.

Thanks

With the calculations of the garage and normal insulation you need 72000 btu to stay around 60deg in a normal 30 deg winter.

Modine input is 75k and output is around 68-70k

You are on the right track with the size you are thinking.

 

[Bert_]

With the calculations of the garage and normal insulation you need 72000 btu to stay around 60deg in a normal 30 deg winter.

Modine input is 75k and output is around 68-70k

You are on the right track with the size you are thinking.

That's way off. 30,000 would maintain 60*+ on a much colder day.

For reference I have a portable 70,000btu heater in my 28x40 garage with minimal insulation. I have had it 60* inside when it was below 0* outside.

 

[gmcgeo]

That's way off. 30,000 would maintain 60*+ on a much colder day.

For reference I have a portable 70,000btu heater in my 28x40 garage with minimal insulation. I have had it 60* inside when it was below 0* outside.

Portable what? torpedo heater? sounds like a vent free heater......??

 

[gmcgeo]

That's way off. 30,000 would maintain 60*+ on a much colder day.

For reference I have a portable 70,000btu heater in my 28x40 garage with minimal insulation. I have had it 60* inside when it was below 0* outside.

you can not go by what heat you have vs what he needs. different types of heating units.

Your reference is invalid

 

[ebg338]

Thanks for the comments. Some additional info - I'm in Illinois just south of the IL / WI border - it gets cold. As far as use - there will be periods of time I'll leave it off and want a quick warm up when I arrive, other times I'll have it on when I'm not there to keep it around 50+/- deg.

 

[ebg338]

Here's what I'm seeing when I use the heat loss calculator on the US Boiler Company website.

 

[Bert_]

you can not by what heat you have vs what he needs. different types of heating units.

Your reference is invalid

Btu's are btu's. The source doesn't magically change the amount of energy needed to raise the temperature. I wouldn't go larger than 50,000 or you are going to have short cycling.

Personally I would suggest a tube heater with the 15' ceiling. The are fairly effective even if the insulation isn't finished yet. They are radiant and heat objects.

 

[gmcgeo]

Btu's are btu's. The source doesn't magically change the amount of energy needed to raise the temperature.

vent free vs vented is not the same

your torpedo heater is 100% efficient. this is why it works so well in your garage. heating wise.... that's overkill for your garage

 

[Bert_]

vent free vs vented is not the same

your torpedo heater is 100% efficient. this is why it works so well in your garage. heating wise.... that's overkill for your garage

Not really sure what you're trying to argue.

A standard 80% heater with 75,000 input is 60,000 output. That's a long way from what that shed really needs. A 50,000 would be 40,000 output which would have plenty of capacity for recovery and not be too oversized. I live in NW Iowa, I do know what the OP climate is like.

My garage has no wall insulation and maybe an inch of vermiculite in the ceiling so 70,000 is about right. If I was to insulate mine I would be looking at about a 30,000 btu.

 

[toyotadriver]

Personally, I would go with the 75k. You live in a cold climate and it’s not well insulated. You need extra BTUs. You also have tall ceilings which increases the cubic feet of heated space. A fan or two will help get that heat off the ceiling but it’s still more cubic space to heat.

I live in a little warmer area than the OP. I heat a 30x40x10 well insulated shop with a 80k. I leave it on overnight sometimes but most of the time it is only used when I’m working out there. Does exactly what I need and has been doing so for at least the last 7 years.

If you were going to heat it all the time I’d recommend a 45-50k.

 

[Bert_]

Delete

 

[gmcgeo]

Not really sure what you're trying to argue.

A standard 80% heater with 75,000 input is 60,000 output. That's a long way from what that shed really needs. A 50,000 would be 40,000 output which would have plenty of capacity for recovery and not be too oversized. I live in NW Iowa, I do know what the OP climate is like.

My garage has no wall insulation and maybe an inch of vermiculite in the ceiling so 70,000 is about right. If I was to insulate mine I would be looking at about a 30,000 btu.

Not arguing,

If you ever get around insulating i would love to know how the 30k is doing for you.

 

[Yankeefarmer]

Here's what I'm seeing when I use the heat loss calculator on the US Boiler Company website.

Was this calculation with or without insulation? I’d be inclined to calculate it both ways to see if you can split the difference, and maybe not get it quite as warm as you’d like on the coldest days before completing insulation. The other bit of my minimal experience that might be worth sharing is that most methods somewhat overestimate heat loss, and the infiltration loss can be one of the bigger culprits here, especially for new, tight construction and taller ceilings. (Others who actually do this for a living may see things differently.)

 

[toyotadriver]

Most shop heaters cannot be sized using house standards. If you have a small shop with no garage doors and well insulated, you’ll be able to get by with a smaller heating source than the same size shop with large garage doors.

I have two 8x9 garage doors on my shop. When I open one or both, that’s a monster hole in the wall that heat rushes out of. Since I don’t heat my shop full time, it cools off without heat. Coldest it has gotten in there so far has been the upper 30s during a deep cold snap. Normally it’s in the upper 40s. I like to heat it to 62-68 depending on what I’m doing out there. There’s a lot of metal inside the shop and metal takes a lot of BTUs to heat up. The large garage doors, while insulated, still **** compared to if that area was framed and insulated. So those garage doors, that houses typically don’t have in the living space, also **** heat out of the shop.

I think a lot of people try to use house standards when heating a shop and in many/most cases, that’s a big mistake. Most shops will need more BTUs than a typical house of the same square and cubic feet.

 

[Bert_]

Another reference.,

I have an electrical business with a 40x100x16 building, good insulation, with (2) 12x14 overhead doors. It's heated with a 100,000 btu tube heater.

According to some of the logic in this thread it should need 300,000btu's... Yet somehow it works perfectly.

 

[Yankeefarmer]

Bert-
My only familiarity with tube heaters is occasionally having been under them at work years ago and at other business establishments. I’m wondering if they provide comfort primarily from radiant heat as opposed to warming the air in the building. In other words, if you were to place a thermometer under them, but shielded from their radiation, what air temperature would they measure?

 

[gmcgeo]

deleted.

I apologize for jacking this thread.

 

[Bert_]

Bert-
My only familiarity with tube heaters is occasionally having been under them at work years ago and at other business establishments. I’m wondering if they provide comfort primarily from radiant heat as opposed to warming the air in the building. In other words, if you were to place a thermometer under them, but shielded from their radiation, what air temperature would they measure?

I have a thermostat. It's mounted where it's not hit with direct heat from the heater. The air temp stays right about where the thermostat is set. The air will cool off if you leave a door open for a while but recovers pretty quickly.

Personally I like a tube heater much better than forced air and would use them anywhere that has enough ceiling height.

 

[Showkey]

No insulation and heating the building is asking for trouble…….ice dams, leaking roof under certain conditions like winter in Wisconsin.

As far as size 50 or 75k both will work. Little farther north I have 1000 sqft detached very well insulated. Original owner installed 75k 20 years it rusted out and the main board failed. I replaced it with 45k both worked fine. 75K probably short cycled some times Under certain condition.

No insulation 50k is going to take a long time to warm and cost a lot to run.

 

[ebg338]

Thanks for the additional comments. Did the heat loss calc with no insulation.

 

[TractorJeff]

I agree with Showkey!
I am on the Il/Wi border with just under 965sqft., 12 foot ceiling, 6 inch walls, with 12 inches in the ceiling and sheetrocked walls that were Tyveked and two 10 by 10 insulated doors, 8 windows and entrance door. I maintain 53 degrees except when I am out there, then I turn it up to 62'ish. 50k Big Maxx on propane.

 

[PoorUB]

You can run all the calls you want. I did HVAC for a living. My neighbor heats a 24x36 shop with 30k BTU. Ok the OP has taller side walls soo 50k BTU assuming normal insulation. The 75k is certainly too large.

 

[toyotadriver]

No insulation and heating the building is asking for trouble…….ice dams, leaking roof under certain conditions like winter in Wisconsin.

As far as size 50 or 75k both will work. Little farther north I have 1000 sqft detached very well insulated. Original owner installed 75k 20 years it rusted out and the main board failed. I replaced it with 45k both worked fine. 75K probably short cycled some times Under certain condition.

No insulation 50k is going to take a long time to warm and cost a lot to run.

20 years is a good run for a heater especially in a extra cold climate where it gets used heavily. 15-25 years is about the lifespan of most gas heaters. Older heaters from many years ago would usually last longer but they were also much less efficient than modern gas heaters.

 

[Showkey]

Agree ……^^^^^^^^^^. I have no real issue with the 20 year life span. I would have replaced the board but closer inspection the unit was very rusty. No idea of the prior use by the prior owner.
The new heater, Beacon Morris looks and acts just like the old heater. Nothing special about either…….other than color they appear to use very similar parts.