The Homemade Heat Pump Manifesto

[AC_Hacker]

Originally Posted by BradC

(I didn't know they needed to be run in, or could benefit from it).

This is great info. I have a friend who has a couple of vacuum pumps that are not getting the vacuum that they used to. Running them in as you suggest just might bring them back to life.

-AC_Hacker

[randen]

We returned from holidays and I reloaded the GSHP with water for the ground loop, in-floor and air handler. While away I didn't want to let anything freeze if the shop got too cold. I will change to glycol when I decide on the compressor size. (leave the 2T or change to the 3.5T).The little 2T compressor has been running none stop for about two weeks. I had a little trouble purging the in-floor. Everything is running well now. The propane refrigerant is performing well. About 6 amp electric load. much less than the labled load for R22. The average shop temp with outside air temp around -6 C deg was 17 C deg., an OK temp. for working. Two nites ago the outside air temp dropped to -19 C deg. The shop temp dropped to 12 C Deg. While the office in-floor heat remained 23 C Deg. Likely due to the large concrete heat storage. The air temp in the office is a nice 20 C deg. (In-Floor heating is the best!!) The loop temp is a steady 8.2 C deg. Returning 7.2 C deg. The water temp out from the HP to the air handler/infloor varies greatly depending if the in-floor is calling for heat (33C to 45C). I have the in-floor set at 25 C deg. and the air-handler in the shop area is running full time like the GSHP. Were adding some attic insulation and if we can get the 2T to cycle and the shop temp up to 22 C deg, it can stay.

Things I've Learned:

-In-floor Heating (hydronic floor) ROCKs
-Propane is an excellent Refrigerant.( but its still flammable)
-You can build a nicely opperating GSHP from junk.
-the moving of heat from the ground to your living space is very cost effective.
-The approx cost of opperation is $130.00/month. vs. Furnace Oil $1000.00/month (for my application your actual mileage may vari)
-you need some basic tools of the trade to be successful. (gauges, vac. pump,torches etc.)
-Insulate Insulate!!
- home made copper shell & tube HXs are very efficient (don't forget counter flow) Approach temp 1 C deg.
-The small circ. pumps are quiet and efficient ( low wattage ) Grundfos,Taco etc
-The heating is slow and steady (be patient let it run)
-Use larger tubes to increase flow.

Randen

[AC_Hacker]

Originally Posted by randen

We returned from holidays...

Nice write-up, randen.

Originally Posted by randen

-Use larger tubes to increase flow.

What part of your total system are you referring to here? The heat pump? The loop field? The radiant floor?

-AC_Hacker

[randen]

Originally Posted

Things that I have learnt:

-Use larger tubes to increase flow.

I think the temptation would be strong to utilize 1/2 pumbing pipe to install our heat-pumps. For the routing to and from the in-floor tubing or to the ground loop. After all
1/2" pipe works well for in house fixture supply. The little circulation pumps work with such little pressure the internal resistance of a 1/2 tube would reduce the flow rates and you might loose flow/heat to the extreme ends of heating loops. Expecially when you include an anti-freeze that would increase the viscosity. The extra cost for fittings and piping is worth the investment in good performance.

Randen

[AC_Hacker]

Originally Posted by randen

Originally Posted

Things that I have learnt:

-Use larger tubes to increase flow.

I think the temptation would be strong to utilize 1/2 pumbing pipe to install our heat-pumps. For the routing to and from the in-floor tubing or to the ground loop. After all
1/2" pipe works well for in house fixture supply. The little circulation pumps work with such little pressure the internal resistance of a 1/2 tube would reduce the flow rates and you might loose flow/heat to the extreme ends of heating loops. Expecially when you include an anti-freeze that would increase the viscosity. The extra cost for fittings and piping is worth the investment in good performance.

Randen

Yes, I agree completely.

I would add to that also to strive to reduce fluid friction, so as to minimize the power required to circulate the working fluid. This would include being careful with pipe diameter to minimize fluid friction. I wouldn't have needed to dig up my loop field if I had followed my own advice.

-AC_Hacker

[AC_Hacker]

* * *

The Homemade Heat Pump Manifesto has gone past 200,000 hits.

Thank you to readers both for reading and for your good questions, thank you to the brave experimenters who had the gumption to venture into new endeavors, thank you to the Webmasters who are behind the scenes keeping everything working.

And thank you most of all, to those of you who have shared your work with the rest of us, because that is how we all learn...

Best Regards,

-AC_Hacker

* * *

[cbearden]

Hi. I just wanted to say thank you everyone, esp AC and randen for all your hard work with these amazing projects. My wife and I are at the initial stages of planning to build a new house. And I'm slowing working towards incorporating everything that I can learn in this thread in our house, as much as I can handle. I have some items ready to learn this skill/art with such as, a small dehumidifier, a vacuum pump, and set of AC gauges. I consider myself a permanent student of living more efficiently. And I hope to teach some of these skills to my 4-year old boy when he grows up.
Anyway, I've been reading your posts for months now and just wanted to say thanks for helping so many getting started with all of this.

[AC_Hacker]

Originally Posted by cbearden

...I consider myself a permanent student of living more efficiently...

cbearden,

I don't think anyone has summed it up so clearly...

You have spoken for all of us.

Best of luck in your projects.

Regards,

-AC_Hacker

[abogart]

Recently, I had an idea. I'm typing it up now because I'll forget about it if I don't.

I really don't have the money to drill wells or holes for a ground source, and I simply don't have the yard for a loop field. I do, however, have an uninsulated basement. Could barrels of water be put in a secluded corner, filled in with dirt, and insulated on all sides to "mimic" a ground source? Or would they simply get cold (or hot) and not do anything? I guess the real question is, would the limited contact with the outer wall and floor be enough to dissipate the heat or cool in the water?

I'm wondering if this might be a good application for a small DIY heat pump.

[AC_Hacker]

Originally Posted by abogart

Could barrels of water be put in a secluded corner, filled in with dirt, and insulated on all sides to "mimic" a ground source? Or would they simply get cold (or hot) and not do anything? I guess the real question is, would the limited contact with the outer wall and floor be enough to dissipate the heat or cool in the water?

Hate to disappoint you...

The basic idea behind GSHP is that you are harvesting solar energy that has been stored in many, many, many tons of earth.

A good approximation of the heat that can be obtained from a bore hole is about 200 feet of vertical bore hole per Ton (12,000 BTU/hr). So you are talking about a huge cylinder that is 200 feet high and from 15' to 20' in diameter (or more).

So, if it were 15' in diameter, that would be 7.5 foot radius (minimum).

The area of a circle is Pi x Radius x Radius

A = 3.1416 x 7.5 x 7.5 = 176.715 square feet

And the volume of the cylinder would be A x h

V = 176.715 x 200 = 35,343 cubic feet.

Density of moist dirt varies, but 100 pounds per cubic foot is a reasonable guess.

Weight of the cylinder = volume x density

W = 35,343 x 100 = 3,534,300 pounds or 1767.15 tons of earth.

A typical house will require around 4 tons of heating, so you will need 7,068.6 tons of damp soil to do it (at a minimum)... and that damp soil will need to be thermally connected to surrounding soil and above all, able to gather solar energy.

So, I'm afraid there is no free lunch... in fact, no cheap lunch either.

Your thinking is good, it just needs to be on a much bigger scale.

* * *

I am repeatedly amazed at how much energy we are all using, and how completely unaware we are of the huge amount consumed.

Do we really know where our energy comes from?

Will it always be available?

-AC_Hacker