Unit Heater - Western NY Pole Barn

[bagsanthony]

Despite this hot and humid summer in Western NY, I've been thinking about heat for the winter. Last year I purchased a property with an existing pole barn. The finished side (the side I will be heating) is 28 ft x 36 ft x 13 ft high. I do automotive work and work under a lift when I'm in it. I have called a number of HVAC supply companies and they are saying a 120,000 BTU should suffice. This is for a forced air Reznor style propane unit heater. This seems a little high to me, but what do I know.... Again, this is Western, NY, we got snow for most of Jan, Feb and March last year and it's not uncommon to have temps in the single digits. Being from this area, I don't need the place to be perfectly warm. I'm used to keeping a shop at 40 and bumping up to about 55 when I work... I hate a toasty shop. Existing insulation is satisfactory- 1990s shop original fiberglass insulation. Looks like R30 in ceiling,not sure about walls I'm sure there is some (covered in drywall) What are your guys thoughts?

 

[PoorUB]

Living in North Dakota I heat a 24x38 with 10 foot walls with 50,000 BTU, and it is too large. We see temps around -30F once in a while. Single digits is a heat wave!

Assuming reasonable insulation, at the most, I would put 45,000-60,000 BTU in that shop. Now realize I have not seen the place and don't know how tight and how well insulated. For what ever it is worth, my shop is not insulated that well!

I have said it here numerous times, I have not seen a building I couldn't heat with 30 BTU per sqft, or abut 30,000 BTU output.

125,000 BTU is crazy!

 

[jack stand]

I'd review your "satisfactory" existing insulation first.
Money spent improving this will save you money for years to come in fuel and immediately with the equipment requirements.
Forking out the bucks for insulation when it's an inferno out there right now is a ***** but your thinking ahead.
You'll probably be wrenching out there for years to come and the "bump it up to 50" scenario is shortsighted thinking and expensive.
Best of luck with your new building and business! It's nice to see a "go getter" these days.

 

[Bert_]

Living in North Dakota I heat a 24x38 with 10 foot walls with 50,000 BTU, and it is too large. We see temps around -30F once in a while. Single digits is a heat wave!

Assuming reasonable insulation, at the most, I would put 45,000-60,000 BTU in that shop. Now realize I have not seen the place and don't know how tight and how well insulated. For what ever it is worth, my shop is not insulated that well!

I have said it here numerous times, I have not seen a building I couldn't heat with 30 BTU per sqft, or abut 30,000 BTU output.

125,000 BTU is crazy!

Great advice!

 

[jblnut]

Unless you have no insulation I wouldn’t do a 125k. That’s huge !! I heat a 54x72x18 with a 120k IBC modulating boiler and it in no way struggles.

I’ll be corrected if I’m wrong here but I think you want to size your heating and cooling stuff for your average loads, not the extreme loads. If you put a heater in that’s way too large it’ll short cycle and won’t last as long. It’s better for it to have to run nonstop and barely keep up when it’s as cold as it’ll get outside than to short cycle.

In Pops shop (32x40x12) he was worried about not having enough heat so he has 2 45k hanging heaters. One is set at 60f, the other at 55f and the 2nd one never runs. He changes the thermostat settings a few times a winter so they both get used but it’s waaaaaay too much heat in that space.

 

[bagsanthony]

Thanks guys for your helpful details! Just to be clear, when you are spitting out BTU numbers, are you referring to input or output?
From what I have seen a lot of these are 80% efficient.... Just want to be clear I'm understanding correctly. Thanks

 

[kaymccampbell]

My 1K sqft shop holds 56-7 degrees just from the heat that emanates from the 89K input, 69K output gas boiler and the nest of copper lines that run to the house above. It's exposed on 4 sides with two-2 inch insulated garage doors, 6 inches of fiberglass in the walls, with an inch of chrome foam under the siding, and drywall inside.

The shop does have its own set of big radiators, but they only get used when I need the heat to let a finish or glue cure.

 

[Bert_]

Thanks guys for your helpful details! Just to be clear, when you are spitting out BTU numbers, are you referring to input or output?
From what I have seen a lot of these are 80% efficient.... Just want to be clear I'm understanding correctly. Thanks

The heaters are advertised by input rating and that is what most refer to them as.

If you do a load calculation, it will give you required output btu.

 

[Sumboodie]

Work is 100x150, 30ft ceiling.

Have 3 250k BTU hanging heaters. They run almost 24x7 keeping it around 55-60* when it's -60* outside.

Home shop is further south. 30x42x14, have a 100k boiler. It runs about 20-22hrs a day when it's -30*. Granted it's not fired that long, fires for maybe 10 mins and off for 10 while the pump still circulates.

They recommend 40 BTUs per sq foot. Granted that is for house space an 8ft ceiling.
Should be based off cubic feet.

 

[Bert_]

I have a 100,000 tube heater in a 40x100x16. I generally leave the stat at 50, turn it up to 55 if I will be in there for several hours.

Generally the coldest we get is -20 but that's not real often. January will be lows a little below zero many days.

Honestly the 100,000 heater could probably be an 80,000. That is input btu, tube heaters are around 80% efficient.

My garage at home is 28x38x9. It is lined but has little to no insulation. 75,000 80% furnace heats it fine up to 55* setpoint.

 

[gmcgeo]

Despite this hot and humid summer in Western NY, I've been thinking about heat for the winter. Last year I purchased a property with an existing pole barn. The finished side (the side I will be heating) is 28 ft x 36 ft x 13 ft high. I do automotive work and work under a lift when I'm in it. I have called a number of HVAC supply companies and they are saying a 120,000 BTU should suffice. This is for a forced air Reznor style propane unit heater. This seems a little high to me, but what do I know.... Again, this is Western, NY, we got snow for most of Jan, Feb and March last year and it's not uncommon to have temps in the single digits. Being from this area, I don't need the place to be perfectly warm. I'm used to keeping a shop at 40 and bumping up to about 55 when I work... I hate a toasty shop. Existing insulation is satisfactory- 1990s shop original fiberglass insulation. Looks like R30 in ceiling,not sure about walls I'm sure there is some (covered in drywall) What are your guys thoughts?

125k is out of line. you need 50-60k They are quoting twice the size needed.

 

[dave*99]

I had a garage in central NJ - 34x23x12. A 40,000 BTU input tube type NG unit heater (80% eff) Heater raised temperature 1 degree per minute. Coldest it usually got in the garage with the heat off for days was 42 degrees. I agree with the 50-60K (input) advocates for your space.
Use a ceiling fan to get the warm air down from the ceiling.

 

[beltfeed]

Despite this hot and humid summer in Western NY, I've been thinking about heat for the winter. Last year I purchased a property with an existing pole barn. The finished side (the side I will be heating) is 28 ft x 36 ft x 13 ft high. I do automotive work and work under a lift when I'm in it. I have called a number of HVAC supply companies and they are saying a 120,000 BTU should suffice. This is for a forced air Reznor style propane unit heater. This seems a little high to me, but what do I know.... Again, this is Western, NY, we got snow for most of Jan, Feb and March last year and it's not uncommon to have temps in the single digits. Being from this area, I don't need the place to be perfectly warm. I'm used to keeping a shop at 40 and bumping up to about 55 when I work... I hate a toasty shop. Existing insulation is satisfactory- 1990s shop original fiberglass insulation. Looks like R30 in ceiling,not sure about walls I'm sure there is some (covered in drywall) What are your guys thoughts?

Do you plan on leaving the temp set at 65 plus 24/7, setting the temp back to approximately 50 when not in use or turning the heat completely off when not in use. It takes more BTU's to recover the temp in a short time frame than maintaining a constant temp.

 

[bagsanthony]

Do you plan on leaving the temp set at 65 plus 24/7, setting the temp back to approximately 50 when not in use or turning the heat completely off when not in use. It takes more BTU's to recover the temp in a short time frame than maintaining a constant temp.

I plan on keeping it at 45 when not in there and bumping up to 55-60 when I work

 

[pcmeiners]

Central PA. My garage 30x36 (x 10' high) , 12k low temp minisplit maintains comfort levels from -7 to 101° so 120k is absurd unless you plan to heat the neighborhood.