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-   -   The Homemade Heat Pump Manifesto (https://ecorenovator.org/forum/showthread.php?t=484)

pachai 03-02-11 10:22 AM

Conduit Through the wall
 
2 Attachment(s)
I mentioned I am having a contractor (steamroller :-)
build an addition, and I'm planning to DIY geo for the
addition and/or the whole house afterwards.

I asked the builder to embed 2 conduits - I think of them as portals - that I can use to put my HDPE through when I figure out how it will be done. (Even if I find a commercial
installer).
(Based on my lot, this location is a safe starting point -
the driveway stretches 60' to the left, yard is to the right :-)

The conduit below the frost line, and is sealed to the wall, and sealing and insulating will not be damaged by subsequent installation. I can fill the pipe with some kind of insulation (even air) until it is needed.
To follow the data model we use at work, Innies and Outies can be separate, and capacity is double from a single conduit.
Lowes sells the NDS pipe, but caps are not available there,
so I made caps out of 2 plastic plates, silicone, 2 plastic bags, and duct tape for a little structural support.
Of course, I can monitor and maintain from inside.

And, when I dig, by whatever means, it is not so close
to the house.
Attachment 1311

Attachment 1312

AC_Hacker 03-02-11 01:42 PM

Quote:

Originally Posted by pachai (Post 12258)
I asked the builder to embed 2 conduits - I think of them as portals - that I can use to put my HDPE through when I figure out how it will be done. (Even if I find a commercial
installer).
(Based on my lot, this location is a safe starting point -
the driveway stretches 60' to the left, yard is to the right :-)

Good going!

Don't know if your driveway is poured yet, but it might be a dandy place for a trench or two... Bare concrete absorbs mucho heat during the summer.

-AC_Hacker

pachai 03-02-11 01:52 PM

Ground loops under the driveway
 
The builder's original quote included a new driveway.
"Because I am going to destroy your current one
with my heavy trucks."

So I said, I can do the driveway after refinance?

THEN I thought of Geo.
The Federal 30% deduction for geo includes cost to
restore the ground after burying the ground loop.
So, the driveway will definitely be done later.


Having room for about 6 separate circuits means,
I can have different minimum loop temperatures
for each loop. The driveway is not allowed to go
below 32, for example. I can turn off that pump
when that loop is cold.

AC_Hacker 03-03-11 12:26 AM

Quote:

Originally Posted by pachai (Post 12265)
Having room for about 6 separate circuits means,
I can have different minimum loop temperatures
for each loop. The driveway is not allowed to go
below 32, for example. I can turn off that pump
when that loop is cold.

Looks like things are definitely working in your favor!

-AC_Hacker

Drake 03-03-11 04:04 PM

OKpiddlr, I'm curious on the choice of different ways of HX on sides of your HP. I'm leaning toward an open radiant system and as AC and others have said plate HXs are not the best choice for that.

okpiddler 03-04-11 05:00 PM

Drake, Are you going to heat some of your domestic hot water (DHW)(shower water) also? On the other side of the compresser (cold) I would use a tube in tube HX. Like the one I made. I will give details on how to make it later. How much heat do you need? This DIY heat exchanger only works for smaller systems.

Drake 03-04-11 06:48 PM

I am planning a hydronic radiant centered heat system for a 500 sq' super insulated(R45W,R60C) passive solar addition. High mass slab floor in both basement and first floor so low temp heat will be ideal. A 80 gl buffer tank will be heart of "open" hydronic loop and best way to heat it is still being explored but will be multiple source. HP being first choice if I can find DIY smaller system(need < 1 ton). DHW will tap out of buffer tank to 30 gl elec tank for temp topping off. Short term heat(24-48 hrs) storage in thick slab basement floor.

Oversizing ground loop for geo heat is not detrimental other than expense is it?

okpiddler 03-04-11 09:40 PM

I may be able to get some prices on some good tube in tube heat exchangers. The exchangers in my Climatemaster have the refrigerant running on the outside and water running in the middle. Or you could make one. I do not rememer exactly how long mine was but it was close to 8' and I know it was between 7 and 9 for a 9k btu comp. I just slid the copper inside flexible pvc leaving the copper at least 6 inches longer on ea. end. 3/8" copper in 3/4" pvc. Roll it up nice and tight, secure with zip tyes. Then slide on a PVC T at ea. end, point your water inlet and outlet in the proper directon and glue the tubing to the t's. Then put a reducer bushing, 3/4" slip by 1/2" FNPT over ea. end and glue them to the T's. Easy so far, here comes the hard part to keep it from leaking. This is what I did and it worked but there was not much pressure on it. I know it would have leaked it I had like 15 or more PSI. You may have a better Idea or maybe use all copper and run the water in the middle. Anyways next I slide on copper reducers 1/2" MNPT by whatever slides over the copper. I think 1/4" in the plumbing dimensions. Then put on some teflon tape and rector seal thread sealant. Thread on and tighten after applying flux to copper. Keep the threads cool with a small stream of water and sweat it together. You could make an extension on that copper reducer so you could do the brazing 2 or 3 inches away. I have done the same thing with all copper straight tubing. I can go out in measure it before it goes to scrap. I only used it for testing with barrels of water.
Right now my evaporator is flooded or close to it. An accumulator will catch excess so liquid will not go to the compressor. This makes for good heat exhchange. On the other hand my condenser is like 95% super heated vapor. I do not have to open my TXV much before I see vapor bubbles in my sight glass. This keeps my high side pressure low enough not to trip my safety lockout switch that I have set at 350 PSI. My plate HX's are only rated for 435 psi.
My exchangers are rated for 17k btu and I am only using 9K. My hot side brass circulator pump is too small. I should have done a pressure drop test across it before ordering the pump. I guessed. I am still very happy with the unit though. Bills are low.
Hopefully you have time and don't get in a hurry. Do it right because it is going to be around for a long time.

AC_Hacker 03-05-11 12:01 AM

Quote:

Originally Posted by okpiddler (Post 12307)
my safety lockout switch that I have set at 350 PSI. My plate HX's are only rated for 435 psi.

What's the story on the safety lockout switch? Where do you get them? How much?

-AC_Hacker

okpiddler 03-05-11 10:23 AM

AC- Hacker,It is at this Dual Pressure Control, 1/4 In Flare Nut - Dual Pressure Controls - HVACR and Appliance Controls - HVACR : Grainger Industrial Supply Link. I put it on the previous page last week. It has to be manualy reset on the high side and is ajustable. The low side is auto reset and has two adustments, cut out and cut in. The price is on the link.
Here is my TXVValve, Expansion - Thermostatic Expansion Valves - AC Refrigeration - HVACR : Grainger Industrial Supply
These prices are high. They may be able to be found for less.


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