insulation question

[Rick Kr]

I have my radiant heater up and running in the shop.

I have the ceiling insulated at R49, but nothing on the walls yet. I am burning 360 gallons/month of propane.

Can anyone take a rough swag with these numbers and tell me how much my propane use should go down when I insulate the walls.

Right now barn is 40x60, 14ft ceiling. R49 ceiling. 5 windows, Doors are insulated.

Walls will be R21 fiberglass, soon.

FWIW. I really like the radiant versus forced air that I had in my old shop.

Thanks,
Rick

 

[Zachary Hoyt]

I have seen a table that tells what % of your heat escapes through the roof, walls and floor, but I can't remember now. I'm sure it is on the web.
Zach

 

[Sid]

I seem to remember reading one time it was something like 14% loss through the floor. Don't know what it would be with concrete. The rest was almost evenly divided equally through the walls and ceiling.
Heres a place to start

 

[MSD]

Lots!!!

 

[oliver power]

I once had a book that told all that stuff. If I remember correctly, it was 80 or 85 percent of the heat loss was through the attic. From the looks of things, you've taken care of that. Now that you've taken care of the attic, I'll bet the percentage escaping through the walls went up quite a bit.

 

[Rick Kr]

After a couple of Sids google searches I finally found a somewhat easy to use calculator. Here's what I found.

With no insulation in the walls, I'm dumping a lot of propane. Calculator said $900/month my bill is $800/month

By insulating the walls to R21 calc says 300/month. I guess my bill be around $400-500 at best. And thats at todays propane rate.

I am trying to get everything finished in the shop, air lines, welder outlets, etc. so I can get insulation in the walls. I will probably be ready just about the time it warms up. arrgh.

Rick

 

[Geo-TH,In]

The formula for calculating heat loss is as follows.

#BTU's/hr = 1/R x area of walls in square feet x delta temp.

#BTU's/hr = 1/21 x (2(40 x 14) + 2(60 x 14))x delta temp.

#BTU's/hr = .047619 x (1120 + 1680) x dT
#BTU's/hr = 133.33 x dT

So the heat loss for just your walls will be 133 BTU's/hr for each degree you heat the room above outside temp.

The heat loss for the ceiling will be:
#BTU's/hr = 1/49 x (40 x 60) x dT = 49 x dT

To calculate the windows heat loss you will need the area of all the window and the U rating of the windows. 1/R = U The formula is the same.

You could say your walls will lose almost 3x more heat than the ceiling. My guess is the windows and doors will lose more heat that the walls and ceiling combined.

You may want to check my math.

Hope this helps.

George

 

[GordoSD]

I'm in SD, it's been in the teens for 45 days, my shop is 40x 72 with 12 foot ceilings. I use about 450 gallons of propane through a Reznor 150k btu for the YEAR. I keep the shop at 42 degrees 24/7 and bring it up to 54 or so working there in the winter. I have 2 16 foot roll up doors also.
Heat is usually turned on in mid Nov, and runs through early Apr.
My walls are from outside in, tin-1/2 inch insul board-R19 Bats-5/8 chipboard interior. Poured slab floor over 2 inch foam. 2 inch foam around exterior 3 feet down. Everything is silicon sealed, light panels, electric boxes. Foam strips at mating suface of doors. It's VERY tight.

Gordo

 

[showcrop]

My shop is 40x50x17. Last year my propane heat was $350.00 for the season, in southern NH.

 

[GordoSD]

Just get the insul and electric in. Air lines are best run on the the walls. You should be able to run the elec wires in a couple hours.
Then stuff the bats, staple the visqueen, and start hanging the chipboard. What you will save in propane you can hire a couple of helpers. Even if you can't get the interior in, the bats and plastic film will do wonders.

Gordo

 

[GordoSD]

Where are you?

 

[Rick Kr]

Gordo,
I am in mid-Michigan.
Rick