The Homemade Heat Pump Manifesto

[AC_Hacker]

These are all really good ideas and certainly much safer.

Will somebody volunteer to do some brazing tests with these gasses?

I was able to convert my propane tourch (which was worthless for brazing) to do the job of copper oxide prevention for about $1.50. I certainly do realize the potential danger involved. I live in a 117 year old wooden house and I have no fire or health insurance, so the buck and the ashes stop here. When I was done with the brazing, I still have some plastic tubing that I can use for something else, and my propane torch works and is still worthless for brazing.

I'm still trying to keep my Homemade Heat Pump budget within $1000.

So will somebody volunteer to do some brazing tests with these gasses, before our readers turn themselves and their families into barbeque?


Regards,

-AC_Hacker

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[Xringer]

No insurance? Don't wait, switch to CO2 asap! (It's great for putting out fires)!

And, CO2 can be used for other things too.. Like getting rid of nasty rodents

[AC_Hacker]

Originally Posted by Maxis

A) 5m of pipes (16mm) on 1m2 - actually it is possible to calculate the needed amount, but than you have to know the heat loss of house. It is quite complicated to do and I was following the rule that you can't have too much. If pipes are closer, you can't feel the cold and hot spots.

B) One loop about 50m long and as equal to each other as possible to make equal circulation in all loops.

C) I have very interesting situation - in my hose are three floors and in each floor I have a little different approach used:

• 1) in basement I had already concrete floors, there I put polystyrol plates for insulation and reinforcement mesh on top to have something to what pipes could be fixed. I didn't need it for reinforcement because in concrete (estrich) were fibers for it.
  
• 2) in first floor I have wooden beams used as floor construction. I have insulated the space between beams with rockwool (for sound insulation) and then I calculated that it will be cheaper to use perforated sheet metal as structure under concrete not OSB. There also reinforcement mesh was used to fix pipes.
  
• 3) In second floor the wooden/metal joist are used as structure (like Lincolnshire Timber Frame design and construction commercial domestic buildings structures) There I had to think about wight of floor because of long distance between supporting walls (about 5m). In second floor I put OSB on the floor and then laid the pipes on it. Than two layers of drywall were put between pipes and space was filled with concrete. In this way I made good contact between drywall and pipe The the last special floor drywall plate was put as finishing layer. With that approach I got floor which is not so heavy as concrete. The drywall is about 1000kg/m3, but concrete about 2500kg/m3. Of course concrete has better heat transfer properties.

I have seen that reflection metal sheets are used for lightweight radiant floors, bit it is more expensive than my approach - I had waste drywall left from wall constructions which I used for that.

Maxis,

Thanks for the answers, but I have more questions...

A) Did the minimum bending radius of the PEX determine the pipe spacing? Did you use bending forms, or did you just allow the pipe to bend as it would and put concrete on top?

C-1) How thick was your polystyrol (polystyrene?)? What kind of mesh did you put on top?

C-2) Can you give more detail on the perferated metal on the 1st floor? How did you arrange the reinforcement mesh?

C-3) I'm very interested in the drywall & PEX you used on the 2nd floor. I had thought to use something similar in my house. How many winters have you used radiant floor heating? How well does it work for you?

Most important, do you have a list or chart of heating degree days for the location of your house? How well are the exterior walls of your house insulated?

Do you have a web link to "reflection metal sheets are used for lightweight radiant floors"?

Thanks...

-AC_Hacker

[Daox]

Originally Posted by AC_Hacker

So will somebody volunteer to do some brazing tests with these gasses, before our readers turn themselves and their families into barbeque?

I'm headed out to the farm supply place today. I'll see what silver brazing rod they have there and get back to you. I have a tank of argon/co2 in the garage.

[Daox]

I didn't see anything there that would do the job. I remembered, once I got home of course, that I just gave all my scrap copper to my father in law when he came to do the garage... So, it wouldn't have done any good if I had found some rod.

[Maxis]

The first I should say that this will be the first winter with HP and radiant floors in my house. I could say something about results only after some time -when it will get colder.

Answers to your questions:

Originally Posted by AC_Hacker

A) Did the minimum bending radius of the PEX determine the pipe spacing? Did you use bending forms, or did you just allow the pipe to bend as it would and put concrete on top?

I have read that one meter of 20mm pipe could give about 18W heat with standart temperatures. That means, if you put 5m/m2 than you will get about 90W. In our area the heat loss range is from 60W to 150W per m2. I have used 16mm pipe and I put about 5 to 6m/m2 - I have not less than 15cm between pipes and then bending is not an issue - I didn't use any bending forms. Actually pipes should be put as spiral (not snake) and then you have only 90 degree bends. With spiral you also will get equal temperature in all room.

Originally Posted by AC_Hacker

C-1) How thick was your polystyrol (polystyrene?)? What kind of mesh did you put on top?

It was 75mm thick. The recommended thickness is 100mm, but I had limitations and couldn't put more. The polyethylene film should be put on top to not allow concrate to flow between plates.
Then I put 5mm (to be able to walk on it ) still reinforcement mesh with 150 x 150 mm cells (than you don't have to mesure the distance between pipes - just follow the mesh).

Originally Posted by AC_Hacker

C-2) Can you give more detail on the perferated metal on the 1st floor? How did you arrange the reinforcement mesh?

It is metal sheet used as roof or wall material. Look in pictures for details

The reinforcement mesh pieces was fixed to each other with special steel wire

Originally Posted by AC_Hacker

C-3) I'm very interested in the drywall & PEX you used on the 2nd floor. I had thought to use something similar in my house. How many winters have you used radiant floor heating? How well does it work for you?

As I said I could comment results after some time. But I have read thet there in Latvia it works fine.

Originally Posted by AC_Hacker

Most important, do you have a list or chart of heating degree days for the location of your house? How well are the exterior walls of your house insulated?

Average temperatures C in my area in each month:
1. -4,7
2. -4,3
3. -0,6
4. 5,1
5. 11,4
6. 15,4
7. 16,9
8. 16,2
9. 11,9
10. 7,2
11. 2,1
12. -2,3

Possible minumum C in each month:
1. -33,7
2. -34,9
3. -30,3
4. -13,1
5. -5,5
6. -2,3
7. 4,0
8. 0,0
9. -4,1
10. -8,7
11. -18,9
12. -31,9

Heating season = 203 days, average temperature 0,0 C

Insulations:
Basement: 120mm polystyrol
1st floor: walls are 210mm logs - cutted from both sides + 50mm wood/concrete plates from outside
2nd floor - 200mm rockwool

Originally Posted by AC_Hacker

Do you have a web link to "reflection metal sheets are used for lightweight radiant floors"?

I didn't use this method, but there is different reflection materials, some are insulation + reflection sheet in one, some are just reflection material. There is the link to one page where you can find how to make it by yourself:
Solar Shed -- House Heating

Best regards
Maxis

[AC_Hacker]

Maxis,

Thank you for your post.

I think that hydronic floor heating is important enough that I have created a separate DIY Hydronic Floor Heating thread as a repository for our discussions on that topic.

I will be posting a response there.

Your information has been very helpful and at least two people at Ecorenovator (Daox & AC_Hacker) are preparing to take action on building their own DIY floor heating. If others are also preparing a DIY hydronic radiant floor install, please don't hesitate to join in the discussion, the more info & opinions, the better for everyone.

This should be a very interesting winter for you since it is your first winter with both a heat pump and a radiant floor.

Many questions & much information to follow...

Best Regards,

-AC_Hacker

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[AC_Hacker]

Now that I have done a bit of brazing practice, and have found a way to prevent the copper-oxide from forming inside the brazed refrigeration lines, I think I'm all ready to go. I have my heat exchangers ready and it's time to strip down the AC unit and see how everything's going to fit up.

If you haven't tackled anything like this before, it's good to cultivate a calm and peaceful mind before beginning.

I like to get a hot cup of tea, a notebook to take notes in, a digital camera to take photos for future reference, and maybe even post a blog.

So find a fairly sturdy surface to put the AC unit on that is at a comfortable height. Since my workshop isn't very much bigger than a phone booth, I set the AC unit on my little freezer.

You'll need a phillips screw driver with a plastic handle and some pliers, preferably with plastic-covered handles, to get most everything apart.

(* MAKE SURE THE AC UNIT IS NOT PLUGGED IN *)

First we carefully remove the metal and plastic panels. I like to save all the screws in a jar lid either for re-assembly or future projects. If a panel refuses to come off, there's most likely a screw hiding somewhere. Be patient, don't force anything.

So the bottom pic shows my AC unit minus the panels.

So, take a few minutes to just look at the unit from all angles. After all, you paid good money for this thing (I think I paid $25), and it may never look this way again...

One of the ideas I like to consider is the possibility of obtaining the maximum amount of benefit with the minimum amount of modification...

In my case, I have decided to make a water-to-water heat pump out of an ait-to-air cooling device, so the modification will be significant.

But we could make an air-to-water device to pre-heat water for a water heater. If we went that route, we could leave almost all of the unit intact and just replace the condenser (the tubing with the fins on the back that get hot when the AC unit is running). We'd still have to extract the refrigerant, cut out the existing condenser, and braze in a refrigerant-to-water heat exchanger. We'd also probably want to remove the rear fan, since it would no longer have a function.

There are other possibilities too, to be considered.

(* EYE PROTECTORS SHOULD BE WORN FOR THE NEXT SECTION *)

Now let's look for the capacitor. It's usually silver, about the size of an orange juice can, and has wires sticking out of the top. The purpose of the capacitor (AKA: 'cap') is to store electricity for the compressor and motor to start. There's a good chance that the cap still has enough voltage stored in it to give you a nasty shock. (* The reason for the eye protection is that if you get a shock, the tool you are holding could get involuntarily jerked in the direction of your face *) Get a plastic handled screw driver and short the connectors together. There are usually three of them so it may take a bit of finagling...

Now we are going to carefully remove the wiring assembly. They are all different, so I can only give general directions.

On top of the compressor, is a plastic cap with a small nut holding it on. Get a small wrench or pliers and remove the nut, and the washer under it. As you remove the nut, notice how much force was required to remove it, usually not very much... remember that because when you put it all together, you won't want to use too much force. Put the nut & washer in the same place you carefully put all the screws. Now carefully remove the plastic cap. You should see something like this:

Your wires might be a bit different. This is the time to get the digital camera out and photograph the wire positions, from several different angles. Also a good time to get the notebook and draw a picture of the wire positions, including any little letters that may be printed near the wire terminals and the colors of the wires that attach there. I promise you that there will come a time when you will want both the photo and the detailed drawing. Now it's time to remove those wires. This is where the rubber-handle pliers come in. Did you already short out the cap? Because some of the wires from the cap go to the compressor... So firmly but gently grip the connectors and pull straight up, one at a time.

Some of the wires will go to the capacitor, which might be out in the open. So, you will want to pull those wires too, but not before you make a photo and do a drawing, labeling any colors and markings on the cap for future re-assembly.

Also, some of the wires will go to the switches on the AC unit. It's time to remove any screws that holds the switch. There will also be a tiny tube from the switch that goes toa little tab in the front of the evaporator the part that gets cold when the AC is running.

At this point, most all of the wiring should be easy to remove, maybe a screw or two, but it should come right off...

Here's what my wireing assembly looks like.

It would probably be a good idea to put the plastic cap and washer and small nut back on the compressor and snug it down, so it doesn't get lost.

So, here's the compressor minus the wires:

Notice the small coil of very thin tubing that is near the bottom of the compressor...

This tiny coil is called the 'cap tube', no relation to the capacitor...

This tiny coil is very delicate and serves the purpose of precisely metering the refrigerant from the condenser (hot part) to the evaporator (cold part). We will need to re-use this delicate part, so be very careful with it, don't bend it if you can possibly avoid it, and if you kink it, then GAME OVER. We will be cutting the tube somewhere around the yellow marks, but that will be a bit later. For now, be very careful around the cap tube.

(* * * * more to follow * * * * )

Regards,

-AC_Hacker

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[Xringer]

Humm, if I was going to hack a small AC, I would try to make a hot water heater,
to keep my water hot and basement cool (and dehumidified), Saving some oil!

Or, leave it Air-to-Air and reconfigure/repackage the AC to make it a Reversible unit.



One that you could install in either direction, depending on the season..
It wouldn't look like this..



More balanced, half in and half out, maybe.?.

Wow, I was just thinking.. Counting the 41 year old unit out in the garage,
I have three small room AC units, that I no longer need..

[AC_Hacker]

Originally Posted by Xringer

Wow, I was just thinking.. Counting the 41 year old unit out in the garage,
I have three small room AC units, that I no longer need...

Hack on Dude!


-AC_Hacker

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