The Homemade Heat Pump Manifesto

[maciej_pl]

Originally Posted by AC_Hacker

I was reading over the paper, and here is a screen shot of the beginning of the conclusion:

Your comment?

-AC

Strange
Obviously contrary to the pictures in the same paper:


Same paper, page 22:
"For coil-type GHEs, when the pipe size increases, the
piping cost slightly increases. However, the increasing
pipe size means the lower head loss, and thus, the lower
annual operation cost of the circulating pump. This is
the reason for the decreasing trend of LCC as the pipe
size increases"


Anyway, there always is a sweet spot for pipe diameter and trench size.
I am not sure if the flow needs to be turbulent, as the exchanger is large and the heat exchange speed is limited by soil, not fluid... That is my personal opinion, and I am no specialist


As far as I know the ground exchangers are always sized for ground conductivity, not piping.
You can always take all the heat offered by the ground, the problem is that one should not collect more heat than is allowed for the given conductivity, otherwise the pipe may freeze or the ground around the pipe will take long time to recover constant temperature. That sometimes renders the exchanger useless.

There are cases the ground freezes around coils. I've talked with one heat pump technician that told me he once was on a service call to repair installation that was 'broken', as the owner described it. He dug to the pipe, it was in June, and the pipe with the surroundig ground was frozen since winter.
More cases of decreasing temperature and freezing are described in the Internet.


In other words: you can size the coil ground exchanger for 100W/tube meter, but that will only work for a short period, because the temperature of the ground will decrease rapidly or even the ground will simply freeze around the coil.

[AC_Hacker]

As is my practice, whenever the Manifesto thread reaches a significant milestone, I feel that it is worth taking note of...

In that light, I would like to thank all of the EcoRenovator tech-folk who do the work of keeping the pages going (and keeping the spam out), for all of their unseen efforts.

I also want to thank those brave people who have acted upon their enthusiasm and tried and succeeded (and even sometimes failed) but who reported back to share their experiences with the rest of us, not only directly on the manifesto thread, but of course on the many other related project threads that are appearing on EcoRenovator. This reporting back is very important... not just our successes, but also failures, as we all learn possibly more from our failures, than from out successes.

But let's not kid ourselves, successes are more fun!!

So, for all of you who have succeeded, congratulations! And for those of you who have not, it's never too late to share your experience, too.

A half-million hits on a topic as peculiar as 'homemade heat pumps' is really something to be proud of.

We all did this together, many people from many parts of the world, we all did this together...

Best,

-AC_Hacker

[ferox]

Hi You are the best
I found this thread long time ago and learned a lot from you and from all hwo posted hear in this forum.
Now I decided to made an air to water heat pump for backup my hot water storage tank.
Nice work and best regards.
Ferox

[Boz86]

Hi,

To introduce myself, mejunkhound pointed me this way. I originally got interested in gshp for the home, lost interest because of the cost.

Interested again for a different reason, have a fixer upper boat with an inop heat pump. The boat tax from any marine related gets expensive, but wife really likes ac when helping me clean, so now up to page 70 to learn how to hack my own.

AC Hacker, another thanks on keeping this going!

[AC_Hacker]

Originally Posted by Boz86

...but wife really likes ac when helping me clean, so now up to page 70 to learn how to hack my own...

Welcome to the parade!

An AC on a boat, huh?

Sounds interesting.

If you could somehow get your condenser in the water, your efficiency should go way up.

Keep us posted as your ideas start to take shape.

Best,

-AC_Hacker

[Boz86]

Originally Posted by AC_Hacker

If you could somehow get your condenser in the water, your efficiency should go way up.

Some boats have under hull cooling for the engine, but I don't think I could mod this one to put the condenser in the water because of the potential for hitting stuff and ruining it. Not with out a lot of other compromises, at least.

Don't remember if I mentioned it in the other post, but one of the boat show vendors said his unit would only produce heat with the water temp above 48F. I got to think that's because of an undersized heat exchanger. Would you agree?

[AC_Hacker]

Originally Posted by Boz86

...one of the boat show vendors said his unit would only produce heat with the water temp above 48F. I got to think that's because of an undersized heat exchanger. Would you agree?

Yes, I would agree. I have run my homemade heat pump with the water coming in from the ground loop as low as 37F and I was certainly able to get plenty of heat. I could have gone lower, but I didn't want to risk freezing my HX... but there was still heat.

The event goes like this... water enters the HX and as it travels through the HX, and heat is removed. If at some point the temperature of the water hits freezing, there will be an ice blockage at that point, then because the water has stopped flowing, the rest of the HX will quickly freeze solid and rupture.

Freezing of the HX is probably the limiting issue before heat extraction efficiency is. If you have plenty of water flowing around your HX, you'll be able to go to a lower temperature, than if your water movement was limited.

If you could pump water past a HX, you would be able to have some control of the rate of water flow there.

If you were using open source water, the probability of fouling is pretty high, even with particle filtering. This would suggest that a brazed plate HX would not be a good candidate, so you'd need to think in term of tube-in-tube or similar.

But you can make it work...

BTW, I spent my boyhood in Maryland... good memories.

Best,

-AC

[waterdigger2]

I am in the process of buildin my own geothermal system. Does any one have the plans on here for how to build the Unit my computer is slow as christmas and this thread is 159 pages

[waterdigger2]

My drilling set up was simple and cheap . Used a electric drill and a compression tee with a pipe inside of it with a lot of holes drilled inside . Superglued the threads so they wouldnt tighten up . Works good for a little of nothin. Used pvc joints to dig with. down to 35 ft . water sand then clay dry sand then more water sand. Hit rock their . So 240/35 is 8rounded off. 7 holes i gotta dig min ? 240 ft to a ton here

[NiHaoMike]

This site browses just fine on my "everyday" D2700 Atom PC. Sounds like your PC is either way outdated or just needs some tuning. (Quick test: Try a Knoppix LiveDVD.)