The Homemade Heat Pump Manifesto

[AC_Hacker]

Originally Posted by greenbean

...sounds like you need something for the pipe to lay on, say v shaped with a clamp or to to hold it.

You're thinking along the same lines that I did...

Here is the 'V-shaped' tool I built for welding the HDPE:

...also pictured here:

...and again here:

Although it could certainly be improved, it worked well enough for my purposes. I used hose clamps on each side, one side was tightened down to keep the HDPE from moving, the other end was left just loose enough so the HDPE could be slid into contact position after the fusion surfaces had been melted. Under favorable conditions I was able to do the welding by myself, but it worked much better with a helper, who held the hot melting tool, while I concentrated on the HDPE.

Originally Posted by greenbean

now if you could have the heat plate in the center that swings out of the way after heating of course then you could join your pipe and use the clamps to hold them in place so they didnt move. a rubber strap oil filter wrench could be modified i think for this.

...I thought about having a pivoting melting tool, but it was very easy to develop proper technique and to do the job by hand.

Originally Posted by greenbean

also maybe have something solid on one end of pipe and on the other end that would put pressure on the pipe to make a good bond between the two.

...the hose clamps worked out ok for this. They were cheap and effective but did taka a few tries to get it working smoothly for me.

But again, my methods can certainly be improved upon, and I am looking forward to seeing what you come up with.

Best of Luck,

-AC_Hacker

[Vlad]

AC_Hacker sorry for criticism.
When you build heating system you should keep in mind that it will run for at least 20-25 years. This is why HDPE fusion must be 100% reliable. I think it is like the weakest link in the chain. It will snap somewhere down 150 feet below. And Murphy’s Law is still here. I am personally going to use socket fusion technique. Fittings are cheap. Here is the link Hdpe Supply: Hdpe Fittings, Polyethylene Pipe, Fusion Equipment They have everything you need and even U-bends, which is specially design for vertical loops. The socket fusion tool (new with all adapters) 300$ on eBay. After you use it you might sell it at discount price. Even if you loose 150$ on it it is still not to much for safety and reliability of whole system.

[Vlad]

I tried 5hp electric motor, but it looks like it is not enough power for my hydraulic system (you get more pressure you lose flow and etc.) . I bought 15 hp gas engine instead. I had to change mounting frame and some hoses. I will try to post some pics. The machine still has electric motor, which is replaced with gas one by now. Sorry about mess around. I just do not have time for cleanup now. Cleanup is my winter project. The reason I wanted to use electric motor is simple. I did not want to kill my neighbors and my family(we have 7 month old boy) with noise from gas engine. But looks like I have no choice. I will buy a box of ear plugs for everybody and a case of beer for neighbors

[Vlad]

My inside the house part is almost done except final connections and outside loop. I was thinking what type of radiant floors to use. I did not want to concrete because it would add more then 20 ton of weight. I did not want to go under sub-floor because of efficiency and drilling joists. I used some kind of hybrid system. I will post pics and details later.

[AC_Hacker]

Vlad, thanks for sending along the pictures. Each one is worth more than 1000 words.

You have done a lot of good work already, and you have much work ahead of you. The forces you are working with are considerably more powerful than what I was using, so again, safety is very important.

You are doing the right thing in scaling up your equipment. What I made was really too light for the job. It's a miracle I was able to do what I did.

Originally Posted by Vlad

...HDPE fusion must be 100% reliable. I think it is like the weakest link in the chain. It will snap somewhere down 150 feet below. And Murphy’s Law is still here.

Vlad, you are quite correct to be concerned with the integrity of the HDPE loop field. You really don't want it to leak and you are going through a lot of work to put it into the ground... you don't want to dig it up to repair it.

The formula for water pressure at depth is:

pressure = depth times 15 divided by 33

So for me, since I went down 17 feet, it would be

pressure = (17 * 15) / 33 = 7.73 psi

(technically, you should add 14.7psi for atmospheric pressure)

pressure = 7.73 psi + 14.7 psi = 22.43 psi

(There will also be an additional pressure from your circulation pump, so I'll guess that to be 10 psi)

pressure = 7.73 psi + 14.7 psi +10 psi = 32.43 psi

...and I did test every joint at 100 psi.

In your case, since you want to go down 150 feet,

pressure = (150 * 15) / 33 = 68.2 + 14.7 + 10 = 92.9 psi

That's certainly more pressure.

(* ...but butt welded joints are surprisingly strong *)

Originally Posted by Vlad

I am personally going to use socket fusion technique. Fittings are cheap. ...Even if you loose 150$ on it it is still not to much for safety and reliability of whole system.

I think you are correct to want to use the strongest, most secure, most permanent method available to you.

Originally Posted by Vlad

I tried 5hp electric motor, but it looks like it is not enough power for my hydraulic system (you get more pressure you lose flow and etc.) . I bought 15 hp gas engine instead. I had to change mounting frame and some hoses. I will try to post some pics. The machine still has electric motor, which is replaced with gas one by now. Sorry about mess around. I just do not have time for cleanup now. Cleanup is my winter project. The reason I wanted to use electric motor is simple. I did not want to kill my neighbors and my family(we have 7 month old boy) with noise from gas engine. But looks like I have no choice. I will buy a box of ear plugs for everybody and a case of beer for neighbors

Good thinking... however it may take several cases of beer.

Originally Posted by Vlad

My inside the house part is almost done except final connections and outside loop. I was thinking what type of radiant floors to use. I did not want to concrete because it would add more then 20 ton of weight.

I know that 20 tons is no exaggeration. Are you looking at 1.5 inch thick gypcrete floors? They are lighter than concrete.

The weight of a suspended radiant floor is a real problem. I have a friend that gave me about 50 pounds of aluminum chips to experiment with as an alternate aggregate for concrete. I did some tests but found that it did improve conductivity, but unfortunately it reacted badly with the concrete and foamed up like bread dough... a real disaster.

There was a guy from Eastern Europe that posted on this blog who built up a hydronic floor out of sheetrock, among other things. I never did hear back from him, but it's an interesting idea.

Originally Posted by Vlad

I did not want to go under sub-floor because of efficiency and drilling joists. I used some kind of hybrid system. I will post pics and details later.

Good thinking... Efficiency is the key.

Good luck, Vlad keep the reports coming in. People learn as much from mistakes as they do from successes, so be sure and tell us the WHOLE story.

(* * * where do you get earplugs for a 7 month old boy? * * *)

Best Regards,

-AC_Hacker

[Vlad]

I needed over 15 cubic yards of concrete. I live in BC Canada I tried to find light fill but I could not. Add hassle, concrete pump, (my house is 3 store) 4 workers to spread. And the worst: if one of them cracks the pipe while walking on them then you have extra headache how to fix that. I could do room by room no rush no hassle. I will find pics of my design and you will see all benefits especially for DIY. Concrete floors give you some benefits like your floor fills very solid and thermal capacity. But cons are:

1 heavy (you might need structural changes)
2 DIY installation almost impossible (unless 1 floor and small)
3 expensive
4 if something goes wrong very hard to fix
5 you need to prepare everything and do it all together
6 thermal capacity or mass in my case is not beneficial because our mild climate (BC Canada) allows to set back thermostat during day time giving extra savings. With concrete floor you start heating your house in fall and stop in spring. Set back is not practical.
7 to install hardwood floor is again extra cost because you will need special glue to glue it down to concrete.

[Vlad]

I found them

Firs I rolled foil over the sub floor, then I nailed 1x2 every 12 inches, I put 1x2 in pairs with 1 inch gap between them.



I put omega (omega is the best do not use u-shape omega shape locks pex and holds it I stapled only plates on each end) heat transfer plates (they are pure aluminum). Tubes are locked in plates (this plates are usually used for under joist installation)



This is just bigger view. The missing spot in the middle is island in the kitchen (there is no point to heat it up)



I covered tubes with 5/8 floor plywood painted black from the bottom (just for fun)

[Vlad]

Please post your comments about my(I do not claim it) design. I do not know how it will work. I do not see the reason for it not to work. It is something between under joist and concrete fill installation. Price-wise it is not cheap because you need heat transfer plates and you need double up your sub floor. I think it will be more efficient than under joist and concrete. It is really DIY friendly you can do it room by room. Floor feels much more solid because of plywood "sandwich".

[AC_Hacker]

Originally Posted by Vlad

Please post your comments about my(I do not claim it design.

I think you are doing great work!

Here's a link to a project that is similar.

And here is a page about people who have made their own heat spreaders.

...I wrote to the guy who did it and never got a reply, but you might have better results than I did.

I think that the style of heated floor you are making is called 'built up'.

Here's a great resource for hydronic flor heating.

...and from that document, here's a graphical display of the improvement that the aluminum spreaders make as compared to staple up.

Obviously a big improvement.

I'd like to know what the diameter of your PEX is, and how long your runs are, and what size pumps you will be using.

Keep up the great work.

Regards,

-AC_Hacker

[Xringer]

Wow, impressive work! I might do that in my den..
No basement under my den, so the floor gets cold in winter.


I read this:
"6 thermal capacity or mass in my case is not beneficial because our mild climate (BC Canada)allows to set back thermostat during day time giving extra savings. With concrete floor you start heating your house in fall and stop in spring. Set back is not practical. "

That got me thinking that your thermal mass is basically the water in the pipe, the pipe, the (thin aluminum) radiator and the flooring lumber.

Then I noticed some air space between the pipes (and radiator metal).

If you wanted to add a small amount of thermal mass to your floor,
without adding a lot of weight, you could add some stone-like,
heat absorbing material in those empty slots. Maybe some cheap Ceramic Tiles?

It might give you a bit of the benefits of a heavier thermal mass,
but would still heat up pretty quickly, when the set-back came on.


When I have used a setback with my forced hot-water (from oil) system,
I always had the set-back kick in, 30 to 60 minutes before the last
person left for work. Since the house would still be warm almost an
hour after the pump stopped.

So, the last person leaving the house would still be comfortable.