BTU,s needed for Pole Building Heat

Robert in Md · Oct 6, 2014

I know this has been discussed several times and I found a formula on the Internet several weeks ago to calculated this with several options for different insulations but I can,t find the formula now.

My building is 36 ft X 56 ft with 12 foot ceiling and 4 inch concrete floor. Ceiling covered with tin and 6 inch fiberglass insulation.
Side walls have bubble wrap, 1 1/2 R Max and 1/2 inch plywood.
I plan on heating with a Modine ceiling mounted Propane heater
Also a 14 X10 and 12X 10 insulated overhead doors and 10 windows around the sides.
Thanks for any help

buickanddeere · Oct 6, 2014

(quoted from post at 21:38:13 10/06/14) I know this has been discussed several times and I found a formula on the Internet several weeks ago to calculated this with several options for different insulations but I can,t find the formula now.

My building is 36 ft X 56 ft with 12 foot ceiling and 4 inch concrete floor. Ceiling covered with tin and 6 inch fiberglass insulation.
Side walls have bubble wrap, 1 1/2 R Max and 1/2 inch plywood.
I plan on heating with a Modine ceiling mounted Propane heater
Also a 14 X10 and 12X 10 insulated overhead doors and 10 windows around the sides.
Thanks for any help

Is that heater vented or invented? How air tight is the building? You can super insulate a building but it gains nothing if there is excess air exchange.location? Desired temp?

Goose · Oct 6, 2014

I'll be interested, too. I have a 30' X 48' building to get some kind of heat into.

Geo-TH,In · Oct 6, 2014

#BTU/hr = 1/R x area in square ft x delta temp(temp difference between inside and outside area)

Happy calculating.

ss55 · Oct 6, 2014

Any furnace seller/installer should be able to calculate it for you when they quote the job, or direct you to some websites.

Rick Kr · Oct 6, 2014

Robert,
I heat a 40x60x14. Walls are R19, ceiling R50. 3 local HVAC contractors all quoted right around an 80-90K btu radiant tube heater and a 225-250K btu hanging heater (Modine or Reznor). I am in Mid-Michigan if that helps at all.

Needless to say I went with the radiant. The radiant cost a little more but I think it was worth it. I did end up with a 125K btu model with 40ft of tube. It will bake you out of there if you want it to.

I keep it at 40-45F when I am not out there for a few days and 65F when I am.

With almost no R value on the walls, and a R6 on the ceiling, you are going to need a fat wallet to keep that place warm, unless you are only going to heat it on occasion. But then you will have sweating issues every time you cycle the temp up and down.

Rick

dpendzic · Oct 6, 2014

you need to calculate the R value and heat loss for each component of the building,
IE:ceiling,roof,walls,windows,doors,etc--also interior air exchange heat loss,

Ted in NE-OH · Oct 6, 2014

My shop is kept at 50 deg. in winter and I turn it up when I go to work. I over sized my heater so that it heats up quick. It takes 15 min to get to 68 deg.

gene bender · Oct 6, 2014

Better go with 8in for the ceiling not much more $$$

Fergienewbee · Oct 7, 2014

It's been a long time, but if I remember: Outside air film is .17, inside film .68 so with R-19 batts in the wall: .17 + 19 + .68 = 19.85. R =1/18.85 = .050. Assume -10 outdoors & 60 indoors = 70 so .050 x 70 = 3.5 btu/sf. With 14 foot walls that would be 49 btu/lf of wall. Rigid insulation (1-1/2") would be about 120 btu/lf. You would get some credit for plywood and any interior finished material, like drywall.You also have to add something for the edge of the slab.

Single pane windows have an R of 1.13; double panes .55. Also need to add for air infiltration which can be as much or more than the window heat loss. Especially true at overhead doors.

Every material has an R value. Can probably find it on the net. Hope this helps some.

Larry

Blackhole49 · Oct 7, 2014

I have a 30'x48' with a 12 foot ceiling that is not insulated in southeast MI that I use for storage and vehicle maintenance. I only run the heat when I'm out there working (last winter nearly every weekend). I use a 125'000btu radiant tube heater hung from the center of the ceiling. On a 10* day, it will maintain 55* without a problem. Mine is natural gas.

Russ from MN · Oct 7, 2014

Insulation is a one-time purchase, you have to buy propane every time the tank is low, just a thought!

GordoSD · Oct 7, 2014

You can run a 50K btu furnace for 30 minutes and get the same heat as a 100K btu furnace for 15 minutes. It's all in how FAST do you want to bring it up from overnight.
I have a a 40x68 x 12 well insulated shop. I hung a 150K Reznor in the back center aimed at the two front overhead doors. I keep the shop at 40 degrees In South Dakota winter. That big heater will bring it up to 60 for working in about 20 minutes.
You should get a minimum of 75K furnace.
I use about 450 gals of Propane a year.

BTU,s needed for Pole Building Heat

Robert in Md

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Goose

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