Drain pipes are ineffective for closed loop earth cooling, too large diameter. Bury multiple thin PE/PP/PEX pipes used for making heated floors on the bottom of the trench, they will dissipate heat from home much better, because of much larger surface of contact. You will need shorter trench, or get better cooling than with drain pipes. Connect them all together on each end.
And 6ft is too shallow, especially in really hot places. Dig deeper, efficiency will rise significantly.
Under the ground temperature changes are delayed in relation to the surface. At around 3m you will get approx 3 month delay.
There is also alternative and better variant of same idea. If you already have a well for water, drill second one nearby to the same water layer. Then just slowly pump water from one well to another through used AC indor unit, instead of refrigerant. You could even connect a water pump (or electromagnetic valve if you will use your already existing water supply system on first well) instead of AC compressor to the AC indoor unit electronics, and you will have a full automatic room temperature control with remote, exactly like with regular AC. No need for digging long trenches and much less pipes needed. And water layers are usually noticeably deeper than 6ft, so lower temperature in summer and so more efficiency. Don't forget about heat insulation for pipes from wells, to keep water cool when it runs from well to indoor unit.
PE/PP pipes survive freezing with water inside, so no need to drain water from system for winter season. However, it's not hard to do that at all, if you're in doubt.
You could calculate estimated underground temperature in your location with good precision by averaging outdoor temperatures measured every hour for year round. This is what you will find at the depth of around 20 meters all year long without noticeable changes.
At the depths below ~200m temperature began to rise at rate around 3°C per 100m.
PS: experimeted with all that stuff long ago, cooling works perfectly, but in our climate heating is much more topical, and such systems are not very good at heating without complex and expensive heat pumps. :)
Drain pipes are ineffective for closed loop earth cooling, too large diameter. Bury multiple thin PE/PP/PEX pipes used for making heated floors on the bottom of the trench, they will dissipate heat from home much better, because of much larger surface of contact. You will need shorter trench, or get better cooling than with drain pipes. Connect them all together on each end.
And 6ft is too shallow, especially in really hot places. Dig deeper, efficiency will rise significantly.
Under the ground temperature changes are delayed in relation to the surface. At around 3m you will get approx 3 month delay.
There is also alternative and better variant of same idea. If you already have a well for water, drill second one nearby to the same water layer. Then just slowly pump water from one well to another through used AC indor unit, instead of refrigerant. You could even connect a water pump (or electromagnetic valve if you will use your already existing water supply system on first well) instead of AC compressor to the AC indoor unit electronics, and you will have a full automatic room temperature control with remote, exactly like with regular AC. No need for digging long trenches and much less pipes needed. And water layers are usually noticeably deeper than 6ft, so lower temperature in summer and so more efficiency. Don't forget about heat insulation for pipes from wells, to keep water cool when it runs from well to indoor unit.
PE/PP pipes survive freezing with water inside, so no need to drain water from system for winter season. However, it's not hard to do that at all, if you're in doubt.
You could calculate estimated underground temperature in your location with good precision by averaging outdoor temperatures measured every hour for year round. This is what you will find at the depth of around 20 meters all year long without noticeable changes.
At the depths below ~200m temperature began to rise at rate around 3°C per 100m.
PS: experimeted with all that stuff long ago, cooling works perfectly, but in our climate heating is much more topical, and such systems are not very good at heating without complex and expensive heat pumps. :)
That's a pretty epic informational response, jus sayin. The Energy Wars are next.