DX Geothermal Pond 4 ton Heat Pump - Page 5

jeff5may · 07-22-15, 04:14 AM

Sounds like a joke to me: a simple proprietary device...

MEMPHIS91 · 07-22-15, 07:44 AM

Yeah same here. Having the manifold in the water really limits the control of the loops. I know the Nordic DX units control each loop with a TXV and can shut off a loop if the head pressure drops to low.

I have 2 of the 064882 KT-20298-2 HFK TXV info of this site http://dms.hvacpartners.com/docs/100...-ACCY-2003.pdf
They look to be the perfect capacity.

AC_Hacker · 07-22-15, 11:54 AM

Quote:

Originally Posted by MEMPHIS91

Sorry I don't think I'm following either one of you. Ac are you saying I might need 2 sets of 3/4 lines run to the pond?
Jeff can you explain that a little more detailed. I was going to look into where the txv went next. My first guess was on the indoor coils. In your opinion what would be best?
Been in the sun too long today. Might have cooked my brains some.

Sorry,

Haven't been reading every word of this thread... I thought you were going HDPE, when I saw the statement about 500' coil of 3/8" tube.

But the laws of fluid friction still apply, even to DX.

-AC

jeff5may · 07-22-15, 02:15 PM

The txv you cited is externally equalized, so pressure drops of your loops is compensated for by the txv. The equaliser port taps into the suction line near the sensing bulb. What this means for you is that you have more options with tubing size.

The big question from me is how many send and return lines do you plan on running underground? To have independent control of each loop, they must be piped separately.

MEMPHIS91 · 07-22-15, 04:07 PM

No problem ac. I see why I was confused now though. Very good articles because I have a up coming project that will use hdpe.

Jeff, I'm fine with having to big of tubing size if it doesn't cause problems. In fact I would like to oversize it some. Do I even need control over each loop? If I do not I was planning on a single run of 3/4 to and a 3/4 from the manifold. Then my loops off of that. I will draw a picture tonight of how I think I understand it so far. I was told I could use the 2012 bobcat excavator for free for a weekend. It pays to know a septic installer.

Drawing not to scale.

Unlike most Dx systems my compressor is not in the same compartment as the indoor coils. 3/8 tubing is $40 for 50 feet. So adding more loops is not a problem.

Pic of txv

randen · 07-22-15, 09:50 PM

Memphis91

Take care with your selection of copper tubing. Some manufactures are supplying tubing with such a thin wall they collapse and kink easily. Stay with tubing intended for refrigeration or compare wall thickness. Your going to save a huge pile of money DIYing don't cheap out on your materials. I'll bite you later.

Randen

MEMPHIS91 · 07-23-15, 05:33 AM

Randen. Yeah I had thought about that. This stuff claims .032" wall for the 3/8 and. 035" for the 3/4. That looks pretty standard size wall for most other more expensive brands.

AC_Hacker · 07-23-15, 11:01 AM

Quote:

Originally Posted by MEMPHIS91

...I'm fine with having to big of tubing size if it doesn't cause problems. In fact I would like to oversize it some...

The only problem with going too big on your tubing diameter is that you need sufficient fluid velocity (feet/minute) to keep your lubricant in suspension. If you went too big in your diameter, your velocity would be too low to assure lubricant suspension, and you could end up with lubricant puddling on one end (yes it can happen), and lubricant starvation on the other end (yes, that can happen, too).

I wish I could find it again, but I did see a detailed patent that had been awarded to some company like Carrier or one of the other huge refrigeration companies. It concerned large DX projects (larger than yours) and it detailed the specific issues with tubing length and diameter, and it stipulated maximum tubing length for a particular diameter and even had formulas that calculated optimum tubing ID for minimum friction loss, while maintaining lubricant suspension.

In your case, you are flying blind and as you have already demonstrated, you have the Blessed Angel of Forgiveness (BAoF) that hovers nearby and protects all gleeful hackers.

Just don't PissOff the angel.

Best,

-AC

MEMPHIS91 · 07-23-15, 03:30 PM

Though we disagree on the angel thing, I 100% agree that I am flying blind. All I know is I would like a DX system if possible. I will run that idea into the ground before trying anything. I will start looking for such a document. I am going to try to reach out to some well known DX installers to see if I can just ask them a bunch of questions. Thanks for the advise ac, your earnings always make me research a project even more than I normally would.

MEMPHIS91 · 07-23-15, 08:54 PM

I got to talk to a HVAC tech that has installed many DX systems. He said the the way I have things drawn out right now will not return the oil. That like AC said the pipes are too big and too long. The longest line set his units use are 125 feet. He also hinted to the fact that he had never seen DX be used in water. I remember a while back AC posted some info from this site Geothermal HVAC Systems ? An In Depth Overview that shows the loops being 5/8 down to 3/8. This really make me think that this system is possible. Someone should really invent a "oil return loop" where the oil can make it back to the compressor and the gas can go as far as it needs to.
I have reworked the system some and have a few options.
First one is the just run several 3/8 loops 200 feet long from the compressor at the house into the pond. This would require spacing between the loops in the ground and add a lot of digging time/ yard torn up.
The next to options are based on this next drawing.

My loop is getting smaller the entire time. From 5/8 out to the pond 60 feet to a manifold at the pond, then 6 loops with 100 feet of 5/16 half way out and 100 feet of 1/4 back in the the other manifold returning with 60 feet of 1/2.
The other idea/ option I had was to keep everything the same but add a 20 feet 1/4 loop for better oil return.

Ideas? Thoughts?

07-22-15, 04:07 PM	#45
MEMPHIS91 Journeyman EcoRenovator Join Date: Apr 2015 Location: Oxford, MS USA Posts: 496 Thanks: 69 Thanked 87 Times in 61 Posts	No problem ac. I see why I was confused now though. Very good articles because I have a up coming project that will use hdpe. Jeff, I'm fine with having to big of tubing size if it doesn't cause problems. In fact I would like to oversize it some. Do I even need control over each loop? If I do not I was planning on a single run of 3/4 to and a 3/4 from the manifold. Then my loops off of that. I will draw a picture tonight of how I think I understand it so far. I was told I could use the 2012 bobcat excavator for free for a weekend. It pays to know a septic installer. Drawing not to scale. Unlike most Dx systems my compressor is not in the same compartment as the indoor coils. 3/8 tubing is $40 for 50 feet. So adding more loops is not a problem. Pic of txv Attached Thumbnails Last edited by MEMPHIS91; 07-22-15 at 08:45 PM..

07-23-15, 08:54 PM	#50
MEMPHIS91 Journeyman EcoRenovator Join Date: Apr 2015 Location: Oxford, MS USA Posts: 496 Thanks: 69 Thanked 87 Times in 61 Posts	I got to talk to a HVAC tech that has installed many DX systems. He said the the way I have things drawn out right now will not return the oil. That like AC said the pipes are too big and too long. The longest line set his units use are 125 feet. He also hinted to the fact that he had never seen DX be used in water. I remember a while back AC posted some info from this site Geothermal HVAC Systems ? An In Depth Overview that shows the loops being 5/8 down to 3/8. This really make me think that this system is possible. Someone should really invent a "oil return loop" where the oil can make it back to the compressor and the gas can go as far as it needs to. I have reworked the system some and have a few options. First one is the just run several 3/8 loops 200 feet long from the compressor at the house into the pond. This would require spacing between the loops in the ground and add a lot of digging time/ yard torn up. The next to options are based on this next drawing. My loop is getting smaller the entire time. From 5/8 out to the pond 60 feet to a manifold at the pond, then 6 loops with 100 feet of 5/16 half way out and 100 feet of 1/4 back in the the other manifold returning with 60 feet of 1/2. The other idea/ option I had was to keep everything the same but add a 20 feet 1/4 loop for better oil return. Ideas? Thoughts? Attached Thumbnails

07-22-15, 04:14 AM	#41
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	Sounds like a joke to me: a simple proprietary device...

07-22-15, 07:44 AM	#42
MEMPHIS91 Journeyman EcoRenovator Join Date: Apr 2015 Location: Oxford, MS USA Posts: 496 Thanks: 69 Thanked 87 Times in 61 Posts	Yeah same here. Having the manifold in the water really limits the control of the loops. I know the Nordic DX units control each loop with a TXV and can shut off a loop if the head pressure drops to low. I have 2 of the 064882 KT-20298-2 HFK TXV info of this site http://dms.hvacpartners.com/docs/100...-ACCY-2003.pdf They look to be the perfect capacity.

07-22-15, 02:15 PM	#44
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	The txv you cited is externally equalized, so pressure drops of your loops is compensated for by the txv. The equaliser port taps into the suction line near the sensing bulb. What this means for you is that you have more options with tubing size. The big question from me is how many send and return lines do you plan on running underground? To have independent control of each loop, they must be piped separately.

07-22-15, 09:50 PM	#46
randen Uber EcoRenovator Join Date: Apr 2011 Location: Strathroy Ontario Canada Posts: 657 Thanks: 9 Thanked 191 Times in 129 Posts	Memphis91 Take care with your selection of copper tubing. Some manufactures are supplying tubing with such a thin wall they collapse and kink easily. Stay with tubing intended for refrigeration or compare wall thickness. Your going to save a huge pile of money DIYing don't cheap out on your materials. I'll bite you later. Randen

07-23-15, 05:33 AM	#47
MEMPHIS91 Journeyman EcoRenovator Join Date: Apr 2015 Location: Oxford, MS USA Posts: 496 Thanks: 69 Thanked 87 Times in 61 Posts	Randen. Yeah I had thought about that. This stuff claims .032" wall for the 3/8 and. 035" for the 3/4. That looks pretty standard size wall for most other more expensive brands.

07-23-15, 03:30 PM	#49
MEMPHIS91 Journeyman EcoRenovator Join Date: Apr 2015 Location: Oxford, MS USA Posts: 496 Thanks: 69 Thanked 87 Times in 61 Posts	Though we disagree on the angel thing, I 100% agree that I am flying blind. All I know is I would like a DX system if possible. I will run that idea into the ground before trying anything. I will start looking for such a document. I am going to try to reach out to some well known DX installers to see if I can just ask them a bunch of questions. Thanks for the advise ac, your earnings always make me research a project even more than I normally would.