Quote:
Originally Posted by RB855
First new thread from a lurker, this is mostly a documentary to spread what I have learned. I have been slowly poking at a heat pump waterheater project for years now. Iv lost count of how many alterations have happened along the way.
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I think you have a very interesting water heater going on here.
Thanks for sharing all the charts and photos, very useful. I wish more people were as good at describing and documenting their efforts as you are.
I don't think we've had anyone substitute R134a for R410a before. Interesting swap and an interesting reason for doing so.
When I first looked at your machine, I had to blink a few times, I thought I was looking at an old VW engine... but then I dialed it right in!
As I recall, one of the comments was a question about why didn't you consider air conditioning? Well... isn't the output from this beast cool air? I think that just a bit of ducting and you would have killed two birds with one stone.
My question is tube length... Most of the commercial units I have examined have longer copper loops that would seem necessary, but they are that way to reduce vibration strain by spreading the strain out over a longer length. And then fair-sized chunks of rubber are put on those loops as vibration dampers. I believe that jeff5may ran into the problem of a too-short loop giving out due to vibration strain.
BTW, with reliably warm Florida air temperatures, and the modest level to which you are heating your water, I think that COP 3.5 is not too much to expect from a Heat Pump Water Heater.
If you get the urge to do another one, you might try a R22 compressor and filtered BBQ gas... I really like that combination. Your skill set is such that anything you build now will go together fast.
But, all-in-all, this is a great effort. You have tried quite a few interesting ideas... and you have them working. That's a good thing, right there. No doubt.
Congratulations!
-AC