Quote:
Originally Posted by AC_Hacker
What I mean is that the heat pump can freeze water in the ground-loop heat exchanger if the loop field is relatively small. I know this to be true, because I have accidentally proven this, much to my embarrassment. If the loop field is sized large enough this will never happen.
You are quite right about exposed pipe, I'm planning to run pipe into my basement below the frost line.
Around here, where heating is the primary mode, some people are putting the 'outside unit' in the attic to benefit from the trapped heat (and leaked heat) there. I assume that the exhaust from the unit in the attic is completely directed out of the attic.
Thanks for all of your information...
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I wonder what would be the most efficient way of raising your loop temp if it threatens to freeze. The choices I could think of were: use the units defrost cycle, shutting off the ground source and firing up your central heater, flushing/exchanging your loop water with cold tap water, or piping water through your hot water heater (ie flushing with hot water).
Once you've got your final, correctly sized system in place you shouldn't have to worry about freezing, but if you're loops are sized for your load and your water temp still drops year to year then you could think about a dry cooler or some other way to add heat back to the ground. You'd be in better shape than us with a dry cooler, cause you'd be only be running it during the summer, and could drain it before temps threaten to freeze.
Speaking of year to year temp drop, in the class the engineer said even a poorly designed/installed system will do great the first year. It's the 2rd to 4th year the bad ones begin to stand out (identified by water temp headed toward one extreme, rather than holding a cyclical constant)
Even in hot climates the pipe needs to be covered: First, if its not insulated where it comes close to the surface, even if there's no freeze potential, you're loosing/gaining heat to the outside air = less efficient. Second, the poly will begin to break down after a few years of exposure to UV (sunlight) so it has to at least be covered.
Putting the "external unit" in the attic in a heating climate is genius! It'll be less efficient for the little bit of AC you do (can counter that somewhat by having extra ventilation openings that are sealed off the rest of the year), but the rest of the time you're pulling the heat that rises out of the house right back inside!
No, thank you! I've enjoyed sharing, and brainstorming. I'm glad you're able to put it to good use, and I wish I was in a position to do the same. It's exciting to be able to help even a little. (cough-post-more-pictures-cough
) even if I can't mess around with a project of my own I can live vicariously through your project!
That Internet archive site, do you have first hand experience posting to the site? It looks like I can upload wave files and they'll convert to mp3 for me as opposed to me uploading an mp3? I gotta get cracking on that audio, I haven't even listened to any of it till just a few minutes of it just now. I have to get the voice recorder files into the computer, then I just want to edit out the extraneous parts, and also figure out which sounds better (recorded on voice recorder as well as direct into the computer, so I've got two different files of the same stuff). Hopefully I can get a segment or two uploaded by the end of the weekend! (as long as I don't get sidetracked modding my car for my upcoming trip)