Thread: Anyone have data for heat loss calculations?

1. Anyone have data for heat loss calculations?

We had our first cold weather and it's time to think about shop heat again. I have about decided what I want but trying to decide on the size I need. Anyone remember how to calculate heat loss? I have .. or had the books with all the heat loss and gain figures but no idea where they are. I have a roughly 30 x 40 daylight basement. More than half is below grade. Large garage door is by biggest heat loss item.

I had drops installed when they ran the gas lines in the house. I have one on either side of the shop. I have decided on propane wall mount heaters. I am debating between two 10K BTU heaters. One on each side. Or just a single 28K heater.

I am wonder if the 10K wouldn't be enough heat but I am afraid I might have to leave it on in really cold weather. SO it might be cheaper to just have the one big heater and just heat the shop when I there. I would probably want a small fan to move the air around the shop.

Anyone have heat loss data? Or may know a web site?

2. Member
Join Date
Dec 2006
Location
Plainfield, IL
Posts
41

Heat Loss

Jeff,

I have a book called Workshop Math that has all sorts of different calculations for the trades. The book was published by Popular Science, I picked it up at a home center I have found it very useful.

There is a section that explains how to calculate heat loss and size you HVAC system to meet you needs. The basic formula is calculating sq footage of outside walls, ceilings and uninsulated floors, say the main floor over a basement or crawl space. The square footage is then factored with a multiplier based upon the heating or cooling zone in which you live. The same equation is worked for all of the window and door is the house as well as ceiling hieghts. All of the equations are added together to give you the total BTU's needed to heat or cool a space.

This the very dumbed down version, if you want more detailed info drop me a line. In no way am I a HVAC professional, I just have a formula that may give you a starting point.

Dan

3. Member
Join Date
Dec 2006
Location
37° 5'16.25"N 76°25'28.11"W
Posts
193
Jeff,

Might check here:

http://www.csgnetwork.com/constructionconverters.html

There's about a bizillion calculators there for just about everything you can think of.

Mike

4. I should have followed up. I found one on line. But the figures seemed a little dubious. I took the info and swapped it from basement to and upstairs space and the heat looses were not very different. I know my basement will stay warmer MUCH longer than my house. But at least it gave me idea of what size heater I needed.

5. Join Date
Dec 2006
Location
southwestern Pennsylvania
Posts
17

Heat Loss

Jeff
You're looking for a Manual "J" (jay)
Daniel

6. Jeff,
I am an HVAC engineer....I'd be happy to do a quick calc for you on with the programs I use at work. All I need to know is the wall construction, window type (double pane, low-e...) and number and size of windows, and I guess you already stated it's 30'x40'...

Just let me know.

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