New Geothermal system questions

Wow, I don't remember mention that you kept it a 60F, you may be experiencing lockouts from time to time, giving the appearence of poor extraction.

 

Not sure what you mean "lockouts" The system ran perfectly all winter with only a couple of times where the water in the well got low enough to dump a couple gpm. (I set up a auto dump at 47 deg EWT). I monitor the all the temps via cameras while we were gone.

 

If you just monitor temps, you wouldn't necessarily spot a lockout if you have auxiliary heat.

 

You system might just be fine. How do you measure EWT/LWT? Sensors mounted on top of the pipes?

 

I have no auxiliary heat just the single stage heat pump. We have a gas fireplace if we had an emergency but have not used it yet.

 

I built Cu temp wells at the In/Out connections to the heat pump. I have Ranco temp controllers on each.

 

Put the same thermometer in the p/t ports to check if the sensors in your wells are calibrated. One being 1F off would indicate that your numbers are 20-25% off/

 

Sorry for the long delay, When I validate the delta T on the water in/out I do use the same probe.
Update:
The system is heating the house to a comfortable level in all aspects, not short cycling but not really performing as it should. It is using much more power than it should for the BTU's it produces.

Here is a list of my updated parameters.

Very simple single stage Dual Air by Coldflow CFX060 with no auxillary heat.

EWT 47 F
Lwt 44 F
GPM 8 (have experimented 6 – 15 with very little change in delta T 3 deg @ 8gpm and 2 deg @ 15gpm)
EAT 69
LAT 83

Current Draw:
Compressor 14 A
Fan 1.5A
Well pump 2A
Voltage 230VAC

Electrial BTUs 11.7 K BTU
Extracted BTU's 12 BTU

COP is 2

Heat pump parameters:
Low Pressure 96psi
High Pressure 300psi
Suction line Temp 35F
Liquid line Temp 82F

Super heat 35-29= 6
Sub-cooling 96-82= 14

I have been working on it with the help from the tech support folks who I bought the system from. They have suggested that it is still low on refrigerant after adding about 20 oz. They would like to see the high pressure up to about 335psi.
I will continue to get the system up to what it should be but only so I can advertise it for sale as a good working 5T unit.

We have concluded a couple of things this heating season.

1) The Dual Air system is not performing as it should.

2) My original assessment of what we would need to heat this house was way over estimated. We have a 5T system and really need a 2T system. I totally underestimated the tightness of the closed cell spray foam and triple glazed windows.Who would have thought that you could heat a 2000+ sq ft house in such harsh conditions with 12-15K BTU's. Our last home built with 6" construction 3000sqft used a 130K oil boiler.

3) We have a nice duct system with comfortable air movement that keeps us warm in winter and cool in the summer. I am sure that when we get the current 5T system operating correctly we will have way too much heat and will have a lot of short cycling. So I am sure we will want to replace the system with a better fit. This system has been a good education and from that point of view I don't regret the purchase.

I have learned a lot from reading this forum and look forward to some of your good advice when I select the next unit.

 

Dan:

They all can leak.

Add the gas, your system is low on charge. Pump it up and continue to pay attention to the operation. I will not tell how many closed refrigeration units I see shipped without enough refrigerant.

Mark

 

Thanks Mark, Well I am surprised that many of these are shipped with low refrigerant. If that happened to refrigerators or window air conditioners they would be all brought back to the store they were purchased at. These units are usually installed by folks who have the refrigerant and know how to add it so I guess it is a cost corner that can be cut at little risk to the consumer. I was a bit surprised when this unit was shipped to me and in the install instructions it said to check the refrigerant level! I certainly have not been impressed with the quality of this unit's assembly.
Is it your experience that even high end models need to have some added?

Another question for you, I have now added about 40 oz of 410a. This increased the High pressure from 275 to 305psi and low from 90 to 96psi. I was trying to achieve the 330psi as the tech support suggested i target. I don't have a good feel for how much 410a it takes to increase the pressure to that point. Does 40oz seem like a lot to you?

Dan

 

That's about half the charge of a GeoComfort 5 ton unit.

 

Would you be able to get for us the brand and model number of the compressor itself? That would be on a label on the compressor housing.

 

Is the R410-A charge weight listed on the unit's tag?

 

The Dual Air CFX060 has a copeland scroll compressor. I have not seen a tag with the charge weight on it but I will look closer later on today and get the compressor model number as well. I will also have a call with the technical support and see what they think.

Thanks Dan

 

Weight should be on the unit tag with model and serial number.

 

Well I am still looking for the compressor model number (I think it is ZP54K5E-PFV) but I have not actually found that number on the uint. I did find on the label "refrig charged 68oz" I think that answers my question. Adding 40 oz of R410a is unreasonable and to not see a significant change in performance.

 

Well I found the Model number partially covered with a Dual Air sticker. ZP51K5F-PEV

 

Correction Copeland Scroll Model ZP51K5E-PEV

 

OK just finished with the technical support (nice folks). They are bewildered and said it was not possible for this system not to have significant functional change after adding 48 oz of refrigerant. He recommended that I run the unit in cooling mode, record the parameters then while running in cooling disconnect the reversing valve and cycle it 3 or 4 times. Then return to heating let it settle and record the parameters again. I followed that process and the cooling parameters were great. Delta T on the water source of 8 deg @ 10gpm and Delta T on the air side 25 deg. When I returned to the heat the poor performance continued with the same very low Delta T's as above. I am waiting on a call back from them to continue the discussion.
Any ideas from you guys?

Thanks, Dan

 

"ZP51K5E-PEV"

Thanks for that...I wanted to rule out the admittedly small possibility the unit was shipped with a too-small compressor.

I'm a bit annoyed with technicians and tech support people focused on refrigerant pressures only. Appropriate superheat and subcooling values should be ascertained to verify proper charge and performance only AFTER discrepancies arise with heat extracted / rejected. You've done all that; I'm suprised tech support seeks a particular pressure as long as SC / SH are good. Pressure will be very much dependent on indoor ambient air temp but SC / SH should stay true to specs.

48 oz is a crazy high amount of refrigerant to add to a system whose nominal charge is 68 oz.

I'll admit...I'm mystified along with everyone else.