Need some help with shop heater.

[Lph008]

I'm getting mixed answers when I used online btu calculator and also reading others posts.
I have a 24x36x12 pole barn in Buffalo, NY. R19 and t1-11 on the walls, R38 and metal liner panel on ceiling, 1 10x10 insulated overhead door, 1 man door, 5 36x36 windows and only vapor barrier under concrete floor. I'm looking to get an appropriate size gas heater, I'd like keep it around 45-50° and bump up to 70 when im out there working or a party

 

[jblnut]

My Pops has a 24x32x14 building with no windows and 1 16x12 door. He has two 40,000btu hanging LP heaters. One is enough to easily keep it 50f in there. The other is used when he wants to bump it up quickly and runs them both. The initial reason was for the two heaters was that I had one 40,000btu heater I wasn’t needing anymore and he wanted 80,000btus total. It actually works very well.

Hope that helps.

 

[PoorUB]

I have a 24x38 with 9 foot walls and heat it easily with 50,000 BTU, actually too large, but I have a residential furnace with AC and that is about a small as they come. North Dakota here.

I did HVAC for a few years and never saw a shop we couldn't heat with 25 BTU per square foot, or in your case, 22,000 BTU. And I am talking truck shops with 20 foot side walls.

Guys like to over size them and I would absolutely stay under 60,000 BTU, but I would bet 40,000 would heat it just fine, 30,000 would do it, but it will take a while to heat it in severe cold.

I have a buddy with a 24x32 with 8 foot walls and he heats his with 17,000 BTU just fine.

People like to argue about this, but I live in a poorly insulated 900 square foot house. My furnace on low fire, 24,000 BTU, will heat the house just fine down to -30F, then it will not keep up and I have to enable second stage.

Also consider, we size heating for the worst conditions. If it takes 30,000 BTU at -20F, it probably takes less than half of that at +20F. A smaller heater will work fine except for the week or so of severe weather, then it might struggle. For the rest of the winter it will heat with no problems.

 

[Yankeefarmer]

My experience agrees with what PoorUB says. Mine is 26x48x15. R19 walls and ceiling. No insulation under slab. Heat loss calculated out at 60k BTU/hr @ -5 deg F. HVAC guy wanted to do a 100kBTU furnace. I installed a 60k cold weather heat pump that puts out about 40 k at 20 degree outside temps. It has plenty of capacity.

 

[Lph008]

I have a 24x38 with 9 foot walls and heat it easily with 50,000 BTU, actually too large, but I have a residential furnace with AC and that is about a small as they come. North Dakota here.

I did HVAC for a few years and never saw a shop we couldn't heat with 25 BTU per square foot, or in your case, 22,000 BTU. And I am talking truck shops with 20 foot side walls.

Guys like to over size them and I would absolutely stay under 60,000 BTU, but I would bet 40,000 would heat it just fine, 30,000 would do it, but it will take a while to heat it in severe cold.

I have a buddy with a 24x32 with 8 foot walls and he heats his with 17,000 BTU just fine.

People like to argue about this, but I live in a poorly insulated 900 square foot house. My furnace on low fire, 24,000 BTU, will heat the house just fine down to -30F, then it will not keep up and I have to enable second stage.

Also consider, we size heating for the worst conditions. If it takes 30,000 BTU at -20F, it probably takes less than half of that at +20F. A smaller heater will work fine except for the week or so of severe weather, then it might struggle. For the rest of the winter it will heat with no problems.

Thank you, I was looking at heaters that are right around 45-60k btu. It's tough not seeing and hearing them operate, as far as noise level. Any input on brand/model? I see alot of posts for the hot dawg heater and also Mr heater or similar

 

[PoorUB]

My experience agrees with what PoorUB says. Mine is 26x48x15. R19 walls and ceiling. No insulation under slab. Heat loss calculated out at 60k BTU/hr @ -5 deg F. HVAC guy wanted to do a 100kBTU furnace. I installed a 60k cold weather heat pump that puts out about 40 k at 20 degree outside temps. It has plenty of capacity.

100k BTU?!!

Some heating "professionals" are completely nuts!

 

[PoorUB]

Thank you, I was looking at heaters that are right around 45-60k btu. It's tough not seeing and hearing them operate, as far as noise level. Any input on brand/model? I see alot of posts for the hot dawg heater and also Mr heater or similar

Modine Hot Dawg is my favorite, but it is hard to turn down the price on the Mr Heater. There are lots of them sold too. Many guys like Reznor, but they will cost about the same as the Hot Dawg.

 

[chinboys]

Manual J calculator based on your location, building materials, and worst-case heat or cooling temperatures.

 

[PoorUB]

Manual J calculator based on your location, building materials, and worst-case heat or cooling temperatures.

Good luck getting that done!

We have contractors in this area the make claims of doing load calcs. In reality they are just plugging in a bunch of guesses and running from experience. I can walk into a house, walk around it for a few minutes and come up with as good of a number as they do.

Getting a genuine load calc is about impossible unless you want to hire and engineer, and nobody wants to pay that price.

I remember one of my contractor friends talking about selling a home system to a customer. He did his usual walk through and gave them a quote. They were a bit taken aback because he didn't do a load calc and the last contractor did one. He asked them if he crawled up into the attic? Nope! Did he asked how the home was insulated? Nope! Plus a few more questions that would be required for a genuine load calc. He then asked them what size equipment they offered? Same BTU furnace and AC my buddy quoted.

Smoke and mirrors!

 

[Jackfre]

Put in a Rinnai EX-38. It will walk away with that space and it is a simple install.

 

[jblnut]

It's tough not seeing and hearing them operate, as far as noise level.

I’d figure that most hanging style heaters are going to be a bit loud. Some louder than others but they’re all noticeable for sure.

The Mr Heaters Pops has aren’t bad but whey they both are running you have to talk a little louder. Not bad but not near as quiet as the radiant in floor setup in my shop, which makes sense of course.

 

[Lph008]

Do they all have to be vented so far out past soffit? I only have 12" soffit, not vented. We can get some pretty significant snow at times and I don't want to have to worry about a snow avalanche bringing it down. I'd much rather run the pipe through the wall than roof

 

[jblnut]

Do they all have to be vented so far out past soffit? I only have 12" soffit, not vented. We can get some pretty significant snow at times and I don't want to have to worry about a snow avalanche bringing it down. I'd much rather run the pipe through the wall than roof

Will your building have a gable end without a roof coming down towards it ? Can you run it out that way ?

It is important to get the exhaust away from the building as it can contain a fair bit of moisture and since it's warm and wet it'll accumulate on anything above it. It it's a non vented soffit I wouldnt think its as big a deal.

 

[Lph008]

Will your building have a gable end without a roof coming down towards it ? Can you run it out that way ?

It is important to get the exhaust away from the building as it can contain a fair bit of moisture and since it's warm and wet it'll accumulate on anything above it. It it's a non vented soffit I wouldnt think its as big a deal

 

[Lph008]

My gas line comes in by the back corner. I was planning on mounting in that back corner (red dot) then venting out the back wall so that the pipe isn't really visible. I could mount it in the middle of the building (yellow dot) but then I'd have the pipe right in the front of the building. Secomd picture is the back where id want ot to exit the building

 

[PoorUB]

Advertiser? Maybe not. Investor? I would think there is some liability there. Perhaps not at Mike directly, but his bank account!

I feel that the combination of investor and advertiser puts him in a bad spot. You toss in money for the development, then brag about how great the homes are that you are bank rolling. Not a good combination in this instance.

Do they all have to be vented so far out past soffit? I only have 12" soffit, not vented. We can get some pretty significant snow at times and I don't want to have to worry about a snow avalanche bringing it down. I'd much rather run the pipe through the wall than roof

I would bring the exhaust just past the soffit. Too close, or under the soffit the wall and soffit will collect condensation and ice from the exhaust.

If you are concerned about snow tearing it off, screw a couple snow breakers to the roof right above the exhaust.

 

[Lph008]

Holy s**t am I missing something? Are the horizontal vent kits really as much or more than the heater itself?? Anyone install mr heater 50k with horizontal vent? What is the difference between the 2? Vertical vent is $120 vs $350-$900 for horizontal?

 

[PoorUB]

Holy s**t am I missing something? Are the horizontal vent kits really as much or more than the heater itself?? Anyone install mr heater 50k with horizontal vent? What is the difference between the 2? Vertical vent is $120 vs $350-$900 for horizontal?

Vertical is probably b-vent, horizontal is stainless.

 

[Jackfre]

Have you looked at the Rinnai? LP or NG. The unit has a built in programmable stat that will also allow you set it as low as 38*f. Taht is used if you yo will be away for a while and don’t want to maintain the higher temp. The vent is also inculuded and requires only a 2.75” hole through the side wall. it has a modulating burner and fan, is cool to the touch and quiet. Very quiet. Self diagnostic. Clearance of the vent to a door or window is 9”. They are extremely reliable. I generally install mine below a window and with the 9” clearance you will be okay. In my shop I make a 2x8 high platform for it to sit on That protects in mostly from gear I’m rolling around and will allow you to set your vent higher to avoid the snow. Vent extensions are available should you choose to raise it further.Assuming the gas is piped to the spot you can install this yourself in about 2.5 hrs