DX Geothermal Pond 4 ton Heat Pump - Page 4

MEMPHIS91 · 07-18-15, 09:01 PM

Randen I am very interested in the compressor you used in your 5 ton build.
I've been looking at the compressors and they look like they are worth the extra money for the vfd. Is it a high learning curve to program the set up?
EDITED TO ADD LINKS
New Top Quality 220V 4KW 5HP Variable Frequency Drive Inverter VFD | eBay

Sanyo 4 8 Ton Scroll Compressor 57K BTU R 22 208 230 V 3 Phase 60 Hz New | eBay

randen · 07-19-15, 10:11 AM

Memphis

I have used this identical VFD. No they are not difficult to program. Sit down take your time and go step by step through their manual.

Now there are some less than clear indication whether or not you can operate these with single phase supply. As luck would have it I have one on the shelf I can test for your application if you are serious. I would only assume you do not have 3 phase power at your home??

A VFD is very nice and has some very useful advantages. They are only within a few dollars of a contactor/relay for a motor of this HP. The 3 phase motors are a little more efficient and usually a few bucks cheaper. I run my compressor at different speeds therefore different out-put (BTU) Case in point air-conditioning this week I was required to reduce the compressors out-put or possibly freeze the evaporator HX. My anti-freeze only protects me down to -15 Deg. C and -25 Deg. C is a few rpm away with this unit. The soft start or ramp-up is really nice as the lights don't flicker on start-up. The VFD has other low voltage contactors to integrate further controls like thermostats and circ. pump relays etc.

Be careful You may be able to find on ebay or others a 3 phase heat-pump with fan and controls inexpensively that you can hack. You many be able to just circumvent the in-put DX to your ground loop. All the safety switches TXVs and reversing valves etc. would be there. I've seen cheap R22 units.

For further discussion latter!! these VFD will operate on DC. You could run your system from a solar PV and or with a battery bank.

This is really exciting, the DX Heat-Pump could be the holy grail. For your application it seams perfect. I couldn't do DX because of my heated floors and solar hot water collection is a totally integrated system.

Randen

MEMPHIS91 · 07-19-15, 11:21 AM

Randen. THANK YOU! Awesome info. Everything I have seen says that using one phase is totally doable as long as the unit (the one I linked) says it can handle 1 phase input. I do not have 3 phase at the house. I am VERY serious about this, I don't see the sense in spending tons of money going DX and not using the most efficient compressor.
Cool I will be watching ebay closely!
My last step before buying is the size of the DX coil. I have been looking for days and the best info I can find is the 100 feet per ton is a good size.
What I'm looking into now is normal closed loop hpde geothermal systems install into a lake. Are they the same size as the ground loops? Are the bigger smaller? Then I will apply that info to the DX sizing.
UPDATE:
"Most often, the same type of HDPE pipe materials that are used for earth loops are used for pond systems; however, pipe length requirements per nominal ton tend to be significantly shorter–and coils can usually be configured in a more compact arrangement–than with buried systems." http://minnesotageothermalheatpumpas...-loop-options/

MEMPHIS91 · 07-21-15, 07:34 AM

On this site. 600 feet of 3/4 = $509.28 500 feet of 3/8 = $386 Total of $895.28 that includes shipping. That is using 3/4 to and from the manifold.

https://www.simplyplumbing.com/catal...SOFT+COPP+TUBE

AC_Hacker · 07-21-15, 09:14 AM

Quote:

Originally Posted by MEMPHIS91

On this site. 600 feet of 3/4 = $509.28 500 feet of 3/8 = $386 Total of $895.28 that includes shipping. That is using 3/4 to and from the manifold.

https://www.simplyplumbing.com/catal...SOFT+COPP+TUBE

You will want to check on fluid resistance in pipe.

The higher the resistance, the more pump power is required to keep your circulation moving at a rate that is acceptable.

The factors that you have control over that affect resistance are:

tube diameter - larger diameter less resistance
tube length - longer tube run means more resistance
velocity - the faster the fluid flows through the pipe (ft per sec) the greater the friction

Fluid resistance is calculated in "head loss".

Taco is a manufacturer of circulation pumps, and they have very good infformation that will help you calculate and optimize your layout so that you will have minimum resistance and maximum flow.

Here are sources of information from different companies. I find that it helps to see the same information ffrom different sources.

If you go with HDPE, you can heat-weld it. If you go with PEX you can't weld it, I tried. But you can use crimp fittings.

When I put in a small loop field in my back yard, I just had 720 feet of pipe. The pump required was 1/4 horse to get the required flow, which was really excessively high, compared to my little compressor.

When I laid out the loops, I had an idea that it might be too long, so I did my layout such that I could tap into the center of the array, and create two arrays, without undo difficulty.

Changing from one 720 ft loop to two parallel 360 ft loops, cut my power requirement by a factor of 4. So my pump only had to be 1/16 HP... huge difference.

You need to do these calculations before you buy your tubing. If I had done this, it would have saved me a day of digging.

-AC

jeff5may · 07-21-15, 11:00 AM

With your dx outdoor exchanger, it depends where you install the txv or metering device. If you run a liquid and suction line all the way out to the pond, you will save money by having smaller tubing for it. If the metering device is close to the compressor, you need to run larger tubing to and from the pond.

MEMPHIS91 · 07-21-15, 02:40 PM

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.

MEMPHIS91 · 07-21-15, 07:26 PM

Refrigerant Flow Controls How It Works | EarthLinked Technologies Earthlinked Technologies

Within the EarthLinked heat pump is a uniquely-innovative, patented technique that enables control of the flow and stability of the refrigerant without any electronic devices, thereby further improving efficiency and reliability. The refrigerant is efficiently managed by two simple proprietary flow control devices: the Active Charge Control and Liquid Flow Control.

These two mechanical controls respond directly to the temperature and velocity of refrigerant flow through the system. They modulate the amount of refrigerant in circulation to assure optimum efficiency at all times. By eliminating subcooling in the condenser, the system operates at lower refrigerant “head” pressures with increased mass flow, which reduces energy consumption, increases heat transfer, system reliability and useful life.

Q and A from DX Geothermal installation - Page 4

I am located in Argentina where absolutely nothing of this subject exists. I am studying a 5Ton system with 5 Vertical BHE, 100ft deep each. The following questions arise:

1) I understand some units have solenoid valves to limit loop operation when condensing. I also understand this is for the condensing pressure not to drop to much. They are really expensive. Not to consider the electronic controller. Do you see a way to avoid using those valves?

The DX systems that I install do not have any valves controlling refrigerant flow. The design is very simple. there is a patented flow control device that regulates the refrigerant flow through the circuit.

2) The boreholes could be at some 45ft away from the unit. What size tubing is recommended. Again, the oil return might be the problem.

Unlike water source systems, DX systems are limited to the total length of line set run and lift. The maximun length of run is 125 ft. This is from the manifolds to the compressor and to the air handler. The maximum lift from the manifolds to the air compressor is 20'. the maximum lift from the compressor to the air handler is 40'. This is standard design and could probably be extended if you contact tech support and have the line sizes resized. As long as these guidlines are followed, there is no problem with oil return to the compressor as the velocities are high enough to ensure its return.

3) When thinking of DX Vertical BHE, don't you have a problem with oil return if you have the 3/8"liquid - 1/2"vapor tubing with no oil traps?

As stated above, as long as you stay within the manufacturers specifications, you won't have a problem. If your local ground temperature is over 60°F, you would have to install 1.5 loops per ton of system capacity. 5 Tons of capacity would require 7 loops 100' deep. They can also be installed in a diagonal configeration as well as pit and trench loops. Depending on drilling cost and land available, it might be cheaper to install a pit or trench system. I have installed all of them with no problems. The customers love the comfort levels and energy efficiency. They are a great system. You can do hot water heating and radiant floor heating with these systems.

If you want to research it some more, go to : EarthLinked Technologies | Geothermal HVAC Systems Earthlinked Technologies. Hope this helps and good luck!
Your help will be appreciated. [/B][/QUOTE]

Questions remaining to be ansered.
Where and how should I control flow?
How long/size of pond loop

jeff5may · 07-21-15, 08:17 PM

Check out this heat pump diagram:

Since it is reversible, there is a txv for each coil. Whichever one is the evaporator (cold) coil will have its txv actively controlling mass flow to maintain constant superheat. Whichever one is the condenser (hot) coil will bypass the txv through a check valve.

The only difference with your unit and the picture is that you will have a dx coil outside, correct? With the pictured unit, it is obvious that the txv is located right next to the outdoor hx coil, since the sensing bulb is positioned very close to the coil. With a run of the mill outdoor unit, this prevents the coil from being saturated and possibly burping refrigerant foam, among other things.

Since you will have a decent distance between your reversing valve and the outdoor hx coil, the lineset will exchange some heat with the ground, whether you insulate it or not. You can put the outdoor txv and sensing bulb close to the reversing valve or close to your dx coil. With the txv placed close to the compressor, your lineset is utilized as part of the heat exchanger. Both lines would need to be able to flow low pressure vapor-liquid-oil froth both in and out. With the txv installed next to the dx coil, the line between the two txv's is a liquid line, and can be downsized since it will always contain slow-moving high pressure liquid.

MEMPHIS91 · 07-21-15, 09:06 PM

Quote:

Originally Posted by jeff5may

Check out this heat pump diagram:

You can put the outdoor txv and sensing bulb close to the reversing valve or close to your dx coil. With the txv placed close to the compressor, your lineset is utilized as part of the heat exchanger. Both lines would need to be able to flow low pressure vapor-liquid-oil froth both in and out. With the txv installed next to the dx coil, the line between the two txv's is a liquid line, and can be downsized since it will always contain slow-moving high pressure liquid.

Awesome diagram. Thank you. I think I understand what your saying now.
As I see it the compressor and reversing valve will be right beside the house. Then the copper 3/4 lines that go to the manifold will go straight down 6+ feet into the ground out to the manifold under water. So I really don't have a choice as to where I put the txv on the outside. Therefore both lines will have to handle the low pressure vapor-liquid-oil froth.Is 3/4 enough to handle that? 7/8 copper wasn't too much more expensive.

"the Active Charge Control and Liquid Flow Control" is a quote from the artical above. The TXV is the Liquid Flow Control. What is the Active Charge Control?

07-18-15, 09:01 PM	#31
MEMPHIS91 Journeyman EcoRenovator Join Date: Apr 2015 Location: Oxford, MS USA Posts: 496 Thanks: 69 Thanked 87 Times in 61 Posts	Randen I am very interested in the compressor you used in your 5 ton build. I've been looking at the compressors and they look like they are worth the extra money for the vfd. Is it a high learning curve to program the set up? EDITED TO ADD LINKS New Top Quality 220V 4KW 5HP Variable Frequency Drive Inverter VFD \| eBay Sanyo 4 8 Ton Scroll Compressor 57K BTU R 22 208 230 V 3 Phase 60 Hz New \| eBay Last edited by MEMPHIS91; 07-19-15 at 07:50 AM..

07-19-15, 10:11 AM	#32
randen Uber EcoRenovator Join Date: Apr 2011 Location: Strathroy Ontario Canada Posts: 657 Thanks: 9 Thanked 191 Times in 129 Posts	4.8 Ton DX build Memphis I have used this identical VFD. No they are not difficult to program. Sit down take your time and go step by step through their manual. Now there are some less than clear indication whether or not you can operate these with single phase supply. As luck would have it I have one on the shelf I can test for your application if you are serious. I would only assume you do not have 3 phase power at your home?? A VFD is very nice and has some very useful advantages. They are only within a few dollars of a contactor/relay for a motor of this HP. The 3 phase motors are a little more efficient and usually a few bucks cheaper. I run my compressor at different speeds therefore different out-put (BTU) Case in point air-conditioning this week I was required to reduce the compressors out-put or possibly freeze the evaporator HX. My anti-freeze only protects me down to -15 Deg. C and -25 Deg. C is a few rpm away with this unit. The soft start or ramp-up is really nice as the lights don't flicker on start-up. The VFD has other low voltage contactors to integrate further controls like thermostats and circ. pump relays etc. Be careful You may be able to find on ebay or others a 3 phase heat-pump with fan and controls inexpensively that you can hack. You many be able to just circumvent the in-put DX to your ground loop. All the safety switches TXVs and reversing valves etc. would be there. I've seen cheap R22 units. For further discussion latter!! these VFD will operate on DC. You could run your system from a solar PV and or with a battery bank. This is really exciting, the DX Heat-Pump could be the holy grail. For your application it seams perfect. I couldn't do DX because of my heated floors and solar hot water collection is a totally integrated system. Randen

07-19-15, 11:21 AM	#33
MEMPHIS91 Journeyman EcoRenovator Join Date: Apr 2015 Location: Oxford, MS USA Posts: 496 Thanks: 69 Thanked 87 Times in 61 Posts	Randen. THANK YOU! Awesome info. Everything I have seen says that using one phase is totally doable as long as the unit (the one I linked) says it can handle 1 phase input. I do not have 3 phase at the house. I am VERY serious about this, I don't see the sense in spending tons of money going DX and not using the most efficient compressor. Cool I will be watching ebay closely! My last step before buying is the size of the DX coil. I have been looking for days and the best info I can find is the 100 feet per ton is a good size. What I'm looking into now is normal closed loop hpde geothermal systems install into a lake. Are they the same size as the ground loops? Are the bigger smaller? Then I will apply that info to the DX sizing. UPDATE: "Most often, the same type of HDPE pipe materials that are used for earth loops are used for pond systems; however, pipe length requirements per nominal ton tend to be significantly shorter–and coils can usually be configured in a more compact arrangement–than with buried systems." http://minnesotageothermalheatpumpas...-loop-options/ Last edited by MEMPHIS91; 07-19-15 at 12:08 PM..

07-21-15, 11:00 AM	#36
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	With your dx outdoor exchanger, it depends where you install the txv or metering device. If you run a liquid and suction line all the way out to the pond, you will save money by having smaller tubing for it. If the metering device is close to the compressor, you need to run larger tubing to and from the pond. Last edited by jeff5may; 07-21-15 at 02:07 PM..

07-21-15, 07:34 AM	#34
MEMPHIS91 Journeyman EcoRenovator Join Date: Apr 2015 Location: Oxford, MS USA Posts: 496 Thanks: 69 Thanked 87 Times in 61 Posts	On this site. 600 feet of 3/4 = $509.28 500 feet of 3/8 = $386 Total of $895.28 that includes shipping. That is using 3/4 to and from the manifold. https://www.simplyplumbing.com/catal...SOFT+COPP+TUBE

07-21-15, 02:40 PM	#37
MEMPHIS91 Journeyman EcoRenovator Join Date: Apr 2015 Location: Oxford, MS USA Posts: 496 Thanks: 69 Thanked 87 Times in 61 Posts	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.

07-21-15, 07:26 PM	#38
MEMPHIS91 Journeyman EcoRenovator Join Date: Apr 2015 Location: Oxford, MS USA Posts: 496 Thanks: 69 Thanked 87 Times in 61 Posts	Refrigerant Flow Controls How It Works \| EarthLinked Technologies Earthlinked Technologies Within the EarthLinked heat pump is a uniquely-innovative, patented technique that enables control of the flow and stability of the refrigerant without any electronic devices, thereby further improving efficiency and reliability. The refrigerant is efficiently managed by two simple proprietary flow control devices: the Active Charge Control and Liquid Flow Control. These two mechanical controls respond directly to the temperature and velocity of refrigerant flow through the system. They modulate the amount of refrigerant in circulation to assure optimum efficiency at all times. By eliminating subcooling in the condenser, the system operates at lower refrigerant “head” pressures with increased mass flow, which reduces energy consumption, increases heat transfer, system reliability and useful life. Q and A from DX Geothermal installation - Page 4 I am located in Argentina where absolutely nothing of this subject exists. I am studying a 5Ton system with 5 Vertical BHE, 100ft deep each. The following questions arise: 1) I understand some units have solenoid valves to limit loop operation when condensing. I also understand this is for the condensing pressure not to drop to much. They are really expensive. Not to consider the electronic controller. Do you see a way to avoid using those valves? The DX systems that I install do not have any valves controlling refrigerant flow. The design is very simple. there is a patented flow control device that regulates the refrigerant flow through the circuit. 2) The boreholes could be at some 45ft away from the unit. What size tubing is recommended. Again, the oil return might be the problem. Unlike water source systems, DX systems are limited to the total length of line set run and lift. The maximun length of run is 125 ft. This is from the manifolds to the compressor and to the air handler. The maximum lift from the manifolds to the air compressor is 20'. the maximum lift from the compressor to the air handler is 40'. This is standard design and could probably be extended if you contact tech support and have the line sizes resized. As long as these guidlines are followed, there is no problem with oil return to the compressor as the velocities are high enough to ensure its return. 3) When thinking of DX Vertical BHE, don't you have a problem with oil return if you have the 3/8"liquid - 1/2"vapor tubing with no oil traps? As stated above, as long as you stay within the manufacturers specifications, you won't have a problem. If your local ground temperature is over 60°F, you would have to install 1.5 loops per ton of system capacity. 5 Tons of capacity would require 7 loops 100' deep. They can also be installed in a diagonal configeration as well as pit and trench loops. Depending on drilling cost and land available, it might be cheaper to install a pit or trench system. I have installed all of them with no problems. The customers love the comfort levels and energy efficiency. They are a great system. You can do hot water heating and radiant floor heating with these systems. If you want to research it some more, go to : EarthLinked Technologies \| Geothermal HVAC Systems Earthlinked Technologies. Hope this helps and good luck! Your help will be appreciated. [/B][/QUOTE] Questions remaining to be ansered. Where and how should I control flow? How long/size of pond loop

07-21-15, 08:17 PM	#39
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	Check out this heat pump diagram: Since it is reversible, there is a txv for each coil. Whichever one is the evaporator (cold) coil will have its txv actively controlling mass flow to maintain constant superheat. Whichever one is the condenser (hot) coil will bypass the txv through a check valve. The only difference with your unit and the picture is that you will have a dx coil outside, correct? With the pictured unit, it is obvious that the txv is located right next to the outdoor hx coil, since the sensing bulb is positioned very close to the coil. With a run of the mill outdoor unit, this prevents the coil from being saturated and possibly burping refrigerant foam, among other things. Since you will have a decent distance between your reversing valve and the outdoor hx coil, the lineset will exchange some heat with the ground, whether you insulate it or not. You can put the outdoor txv and sensing bulb close to the reversing valve or close to your dx coil. With the txv placed close to the compressor, your lineset is utilized as part of the heat exchanger. Both lines would need to be able to flow low pressure vapor-liquid-oil froth both in and out. With the txv installed next to the dx coil, the line between the two txv's is a liquid line, and can be downsized since it will always contain slow-moving high pressure liquid.