The Homemade Heat Pump Manifesto

[AC_Hacker]

Originally Posted by BeerGrylls

I guess a potential problem is that the guys wanting to cool their pc gear are not necessarily concerned with power consumption. We are not just interested in the hot end, but a high COP hot end. Do cascading systems have low COP ? I would assume so.

It might be lower, but in severe climates, where single stage wouldn't work at all, a cascade configuration, even its COP was lower, and complexity was greater, may be very desirable.

What makes me think this is that there was a company that sold just such a severe climate system, but apparently they 'cheated' on the margin of safety and the failure rate of systems in service forced them out of business.

This says to me that cascade systems can work but they require careful design.

-AC

[doug30293]

Originally Posted by AC_Hacker

It might be lower, but in severe climates, where single stage wouldn't work at all, a cascade configuration, even its COP was lower, and complexity was greater, may be very desirable.

-AC

Carnot was an idealist. His equation does not account for pumping losses, friction, weather, the need for fans, and all those other things that make a heat pump work. As Carnot efficiency drops with delta T you reach a break even point where availability of Q is zero.

At that point it makes more sense to use hydrocarbons to run a generator and simply recover the waste heat. The optimist would recover it with a heat pump.

[nokiasixteth]

jeff5may
ive been workin on another thing that has took all my time up and havent had time to really do much on the ac . I finished it yesterday . Just have a little fine tunin to do .
I have a ac with the knobs (old) and a new one . With the remote and push buttons(new) . Havent looked into the new one . Plannin on messin with the old one first.

[nokiasixteth]

Originally Posted by AC_Hacker

jfweaver,

Yes, for sure, I do understand that.

But what is obviously of most interest to me is what is coming out of the other end of the cascade systems.

I mean when you have an extreme system that is able to force a CPU to ungodly-low temperatures, it means that the same cascade technology could be used to extract heat from air that is only partially warmer than ungodly-low temperatures.

Same tech. The Extreme guys are interested in the cold end, we're interested in the hot end. Same tech.

-AC

Im interested in the hot and cold end. Extract heat during winter from ground and give it back in summer .
Did build a solar heater though worked pretty good panel got 197 degrees . Had it syphoning into the house . Then put a small window fan against the outlet so suck it through. Instead of copper pipes and all . I used window screens

[AC_Hacker]

I just ran into a very interesting project on Build It Solar.

We have a guy who has combined Ground Source Heat Pump with PV Solar to supply the total heating needs of his house!!!

Essentially free heating is claimed.

Here is a detailed, illustrated PDF that explains the whole thing.

Great job!

-AC

[pinballlooking]

Originally Posted by AC_Hacker

I just ran into a very interesting project on Build It Solar.

We have a guy who has combined Ground Source Heat Pump with PV Solar to supply the total heating needs of his house!!!

Essentially free heating is claimed.

Here is a detailed, illustrated PDF that explains the whole thing.

Great job!

-AC

Thanks for posting. It was a good read.

[cbearden]

AC, I just wanted to say thanks again for all your hard work and all of the info that you've shared here! All of this is really inspiring and helps people like me start out from the bottom up on a project like this.
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I was hoping someone could help me verify my temps that I'm seeing in a first test borehole.
I live in Arkansas, and the temps around here lately have been anywhere from 50-75 during the day, and 33-50s at night.
I have a test loop of 3/4" hdpe pipe down to 12' in my test hole that I completed. I hit mostly clay on the way down to 8'. After that it was a mixture of clay/sand for the next foot or two. Now it mostly sand.
I've rigged up a insulated container with a small pump, similar to what AC did in the first of this thread. My pipes are insulated going into the ground. I've got a arduino hooked to a temp probe inside the container. And that's been logging temp data to a small local linux server (emoncms) I setup for this purpose.
The attached image show my temp graph that I have setup to monitor temps from water circulating in my borehole. I haven't applied heating or cooling to this yet. Right now, I'm trying to get to a stable foundation that I can use to verify that everything looks good with my temps here.
Would I be correct to assume that the temp swings in my graph from day to day are because of the heat gains/loses from outside temps from day to night? I guess I would have thought that the water would be effected less than this, esp going 12' down.
I'm still working on coming up with a solution to heat the water in the meantime.
Thanks for your insight!

[cbearden]

This is a pic of my setup. The blue wire is a network cable I used to wire up a DS18B20 temp sensor to my arduino. now that I look at my own setup, I notice some of the tubing doesn't have insulation around it as it enters into the container.
Anything else I need to pay attention to?

[AC_Hacker]

Originally Posted by cbearden

This is a pic of my setup. The blue wire is a network cable I used to wire up a DS18B20 temp sensor to my arduino. now that I look at my own setup, I notice some of the tubing doesn't have insulation around it as it enters into the container.
Anything else I need to pay attention to?

It is so great to see you doing this, it was exciting for me when I did it, maybe for you, too.

I think those swings are not so big, but mostly they're from ambient temp changes... the smaller you can get them, the better.

With the ambient temp swings you mentioned, you are going to have temp swings from above the ground, through your styrofoam cooler, and also through your foam insulation on your PEX tubing.

The ambient swings will affect the ground temps also, but the deeper you go, the less the amplitude of the temp swing. Also, the deeper you go, the more the ambient swing will be delayed... kind f of like a phase shift.

Just imagine the daily temperature swing being a 'heat pulse' that slowly travels down through the ground, and the deeper, the later it arrives.

You have the right idea with your setup, but I do think that your styrofoam cooler is thinner than it should be. I recently discovered a good, free source of very high grade styrofoam boxes with tight-fitting lids, and that is any large drug store. It turns out that vaccines and medicines are shipped in those boxes, and the pharmacies have a disposal problem. Just ask around. I had good luck at Walgreen's.

Another source of high-grade styrofoam boxes is organ-transfer boxes. If you have friends who work in a hospital, ask if they can help.

Also, there are beef companies that ship frozen meat to peoples homes. I see the empty boxes showing up in Goodwill.

The cool deal would be if you could put a smaller box inside of a larger box.

Also, you might see if you could do something similar with your tubing insulation.

These things will reduce your error.

Also, a cardboard box over your whole setup would help, too.

I had sun shining on my test setup, so I used a space blanket to reflect as much of the solar energy away as possible.

I take it that you looked over the paper that I linked to. One of the things they mentioned was to disregard the very beginnings of the test logging, as the rest of the curve provided reliably accurate data.

I think that the best and most meaningful way to do it, is to test holes that are as close to being identical to the holes you will use, as possible.

And to use a heat source that will provide heat output approximately the same as you surmise your bore hole will produce.

I am interested in your Arduino logger setup, too. Be sure to include hardware & sketch info on that part.

I can't wait to see how your test turns out.

BTW, from what you said about the soil formation, it might be possible for you to use a rotary drill and a mud pump and go really deep. You'll need drilling mud or Bentonite mud to 'skin' the inside of the hole to prevent sand from caving in.

Holes as deep as 200 ft might be possible.

Keep us posted on your testing.

Best,

-AC_Hacker

[randen]

Just a little side excursion. Have a look at Drakes Landing here in Canada. (www.dlsc.ca) See what they have done with their bore holes. Over 90 % of the heating load comes from the bore holes.

Randen