Nicola Marchi wrote:Hi Mike,
I just saw this question and it got me thinking that I'd seen these calculations before.
Unfortunately it's complicated and I can't give you a number that will work for everyone, but the attached white paper goes through the math, and has an example for a home in Southern Germany.
Everything's in metric unfortunately.
The concept behind the math is that essentially, what matters is the temperature of the air you're trying to heat/cool, the temperature of the earth where to tube is passing through, the thermal conductivity of the tube itself, the size of the pipe, and how long it stays in the tube before coming into your house.
I've never done the math, but you can probably come up with a good approximation by comparing his +/- 138' of 5" diameter pipe, buried 2-5 feet below ground, to pre-condition the air for Southern Germany. If you are in a milder climate you can probably use less, if you're in a more extreme climate you will probably have to use more.
THAT is some serious math...the contractor is getting with a designer for this aspect of the build, those equations are a bit arcane for my simple mind but thanks anyway. I have DL'd it in case he asks.
