11,000 BTU DX GEO Heating

[MEMPHIS91]

Thanks Jeff! I'm going with 24VDC, just ordered it!
I found awesome news! People I'm talking with say that a 1-2 ton oil separator will work just fine on this build. So I ordered this beauty! Q E HVAC R Refrigeration Oil Separator 1 2" ODS New | eBay

Parts come in! First off is 20 on 316 stainless steel for the coil in the fish tank and 2 sizes of cap tube. (Might not need them for this build, but just wanted to be sure.)

Next is 5x SUD115 and 45% silver braze

And finally the 2 Inkbird Thermostat/relays


This build is going to have all the bells and whistles because I need to be able to really test it out to see if the 4 ton build will work as planned.

[MEMPHIS91]

I found some interesting data on R600a. Looks like higher temps at lower pressure. I might shoot for a blend.

http://www.tecumseh.com/~/media/Nort...A-and-R290.pdf

[MEMPHIS91]

I reworked the fan and figured out the crazy chinese wiring.


The copper came in!


I ordered the cheapest I could find. So I was happy to see some really well made tubing.


Digging has been pushed til NEXT sunday.

[jeff5may]

I guess this means you're not using the OEM power supply or onboard relays to control the fan or compressor any more. Make sure to fuse everything correctly.

As to the r600 (butane) issue, it has a vapor pressure a little less than r134 or r12. At evaporator saturation temps below freezing water, your suction pressure is going to be near 0 psig. At seawater freezing temp, evaporator pressure is below atmosphere. I doubt your compressor could move enough mass to keep its motor cool.

Since your compressor is made for r410a, it needs to see a suction pressure in that range to keep cool within its operating envelope. Discharge pressure is not so much an issue as far as the compressor is concerned. All it really cares about is temperature.

What I would do is install some piercing valves on the stock unit and run it like they built it. Slap some gauges on it and log suction and discharge pressure for both sides. Choke the airflow on each side separately and observe pressure changes. Run the bad boy at all speeds and measure away. This will give you a detailed snapshot of the operating envelope it was designed to survive within.

After a decent approximation is made, you can blend propane and butane together to get a mixture that will satisfy your suction pressure range while giving you good discharge and condensation temperature. Raw high-side pressure will be lower than that of r410a, which in my mind is a good thing. Less pressure means less stress on everything.

[MEMPHIS91]

Jeff, yes I have decided to not use the control board for the fan. I will be sure to have fuses where needed and everything on a gfci.

That is a very good point about the butane. I will be careful on how I use it, if any at all. This system is mainly for heating anyway.
Sadly the unit was out of 410a when I got it. The unit had fallen out of a window and on some trash below that busted a hole in the condenser.

When I charge I am going to do like I did with the water heater and charge by outlet temp, BUT I will keep a close eye to make sure the suction side is high enough to provide needed cooling, that is the main reason I went with 3/8 instead of 1/4. Thank you for that advise, changing the "perfect" blend only matters if the system works right.

As far as cooling the compressor goes, I plan to place it right before the condenser coils so the cooler air is drawn over it. I need to post the diagram soon, but for now MORE STUFF CAME IN!

A couple cheap temp sensors to constantly measure discharge and suction temp.

A few relays


The awesome and amazing QOS-12 Oil Separator!


And just for fun, a shot with the inspection camera down the inlet! The outlet looks the exact same way.


The building begins soon. I post some final diagrams and numbers soon as well.

[marx290]

Originally Posted by MEMPHIS91

I found some interesting data on R600a. Looks like higher temps at lower pressure. I might shoot for a blend.

http://www.tecumseh.com/~/media/Nort...A-and-R290.pdf

Check out the ASHRAE series of books, especially the Fundamentals years. My early nineties copy, lists many properties of propane, butane, isobutane, and many others. They also have beautiful log(p)-h diagrams of each refrigerant saturation curve. Here is a a link to a pdf version. I'm not sure if it is still good, but I know there is one out there.

Ashrae Handbook Standards Download

Go to Abebooks.com for a hard copy. They make a lovely reference.

[marx290]

Originally Posted by jeff5may

You can use a bullet strainer as an oil separator. Supco no. SUD 115 is the common one. Two Tubes facing up, single tube facing down. Bottom tube feeds long, small diameter cap tube back to suction line.

That is great! I wasn't sure if it would work. My best plan of attack for a oil return, was a sort of vortex separator on the discharge of the compressor, where oil would tend to fall to the bottom. A capillary tube would carry oil back to the compressor suction. I figure some sort of strainer would be advisable, in order to avoid plugging the capillary oil return line. I suspect that even a well designed system would compromise volumetric efficiency slightly, but would certainly be necessary for compressor health in some instances. Then again, keeping the heat exchanger walls cleared of oil, could improve thermal transfer too.

That's interesting. Thank you

[MEMPHIS91]

marx290, thanks for the links, the link was down, but I did find a google drive through that same site with a GOLD MINE of info.
https://drive.google.com/folderview?...DQ&usp=sharing

I am just now fully learning the P-H diagrams. I was always a try try try try til it fails then try try try again til it work kinda guy. But I am putting tons of research into this build. So I knew I needed to start with some basics of the math/science behind it all.

[MEMPHIS91]

Progress has been made!
So I started just loose fitting things. First the discharge on the compressor to the intake on the oil sep, not the best idea I know, see below. -1/2"-

And the discharge of the oil sep into the reversing valve -1/2"-
.
I knew the discharge from the compressor would have too much vibration to have a straight run to the oi sep, so I fixed it with a big loop.

The evap(now the condenser) had 2 cap tubes, so 2 intakes, I saved the cap tube and brazed some 1/4" onto them.

Then I ran the 1/2" from one side of the discharge of the reversing valve to the 2 1/4" intakes on the condenser.

The 2 1/4" tubes fit perfectly inside the 1/2". BEFORE

Brazed thoroughly. DURING

I was going to clean it up and take another picture, but I decided to move it into place first, and of course picked up the still super hot 1/2" line...... needless to say I am pecking with 2 fingers in between icing the burns in between typing...

Any way, next question, how much oil do I add and do I add it to the oil sep or the compressor? All to poe was drained. I have been looking for a while for the answer, still searching now.
Also I'm think 1/4" is to large for oil return. Would 1/8" be better?

[MEMPHIS91]

Howdy guys I got a lot more done thanks to the help of a GOOD friend.

First I swagged the 3/8" lines, its SO much easier than 1/4"


Then I laid out the line, brazed it all up, pulled a vaccum for several hours, made sure I had NO leaks, then zip tied about 20 bricks to the end that is going in the water.



Then the digging started, I got down to 9 feet deep in some places, but never less than 6 feet. When we got close to the pond the machine tried to slip and almost went for a swim, so I will have to dig about a 4 foot spot by hand.




I insulated 2 feet down as it came into the green house.