Quote:
Originally Posted by IdleMind
I am about to start a small heat-pump water heater project. It will be very small because I am new to this type of development, so a small first step. I found a 2.5 gal 120v electric water heater on craigslist which I may buy tomorrow.
I intend to mount it in my basement under the kitchen to feed the kitchen sink and dishwasher. We waste a lot of hot water waiting for it to get from the water heater through 3/4 copper pipe through a low flow faucet. The water is usually just barely warm by the time your done washing your hands or rinsing a dish. So this will get hot water to the faucet faster with less wasted heat.
I have a dehumidifier which will donate the compressor. Then I'd like to try to make a passive evaporator. It would be a small tank of water/anti-freeze. It could have some fins welded on to increase surface area.
My basement is around 50F in winter and 70F in summer. For the kitchen faucet I am thinking 95/100F would be hot enough. Right now the cold water coming into the house is 53F.
Anyway, I am new to the forum and wanted to start a thread so I could share what I learn and learn from you. Also, I never heard of a heat pump water heater before reading about it here, so thanks for that.
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Welcome to the forum!
Your project sounds very doable. Your tank size is quite small, but it will be interesting to see how it works out.
You will need specialized tools for the job. jeff5may is currently doing a
similar hack, and he has listed the tools. The tools don't need to be new, and you can fudge a bit here and there.
[* jeff5may is using an Oxy-Map gas brazing rig which is great, but a simple map gas torch will work at lower cost *]
$40 at Walmart
You will need to be able to braze copper,
absolutely not solder. In the refrigeration trade they call it soldering, but it really is brazing. Possibly, jeff5may might expand on that in his project.
If your de-humidifier uses R134a, stick with that. If it uses R22, propane (camping gas) will work extremely well, but it is highly flammable so become aware of all the dangers and all the work-arounds.
For a project like yours, select the very smallest compressor you can possibly find. De-humidifiers are rated in pints-per-day, in your case, smaller is better.
Be aware that your compressor will have a very thin tube called the cap tube (capillary tube) that is perfectly matched to your compressor. If you use the cap tube that came with your compressor, your project will be greatly simplified, and your success more easily assured.
Take and post loads of photos as you go along, and we will be able to best advise you. Good luck!!!
-AC_Hacker