New Geothermal system questions

Discussion in 'Maintenance and Troubleshooting' started by Dan Dillner, Jan 20, 2014.

  1. Dan Dillner

    Dan Dillner Member

    Thanks Curt for prompting me to get the number and capacity. We did start all this after we verified that the functional parameters EWT-LWT, EAT-LAT were no where close to what this should do. It is most interesting to me that in the cooling mode they are right on what we should expect.
    The tech support has contacted the manufacture and discussed with their engineering support. Their take was that somehow this thing got our low on refrigerant and it may still need more. The plan will be to evacuate the system and load 68oz back in and then we will know exactly what we have. This will be a while as we are now traveling south (that's what old retired engineers do!).
    Last edited: Jan 21, 2015
  2. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    How are we adding R410? Is the can upright when you do it?
  3. Dan Dillner

    Dan Dillner Member

    Joe, After purging the lines and connecting to the service ports and taking pressure measurements. We flip the can upside down and throttle the low pressure valve every 5 seconds or so. Letting the system pressures to settle then record measurements. I have the can hanging on a scale so I can check measurements every 4-8oz.
  4. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader


    R-410 A is a blend. Do not let anything out of the can if it is not upside down. Not even line purges. I hope you guys changed the filter dryer and took the system down to 500 microns at least.

    The oil that is used with 410A absorbs water. Must have a new dryer.

  5. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Evacuate and re-weigh-in is the best plan to be absolutely sure of proper charge...assuming the manufacturer is indeed sure of what constitutes proper charge.
  6. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader


    Ever watch them build this stuff? It is a wunderment to me that any of it works. Most charging stations I have seen on assembly lines are time on time off then crimp and braze the fill tube.

    To many of the performance tables look like they have been cut and pasted for me to think the manufactures "know the exact weighed in charge". I have no proof that they are clueless just 30 plus year as a field service tech.

    I should have gone to dental school.

  7. Dan Dillner

    Dan Dillner Member

    That is the plan but it will have to wait till we return. The Mfg technical rep said that "this thing must have gotten out without a complete charge." So they are willing to have the system evacuated and recharged to ("what the label indicates") on them. I am not impressed with the brazing on several places and the system came with a couple of minor assembly errors. This mfg does not publish much of anything for technical support or data except the AHRI data and certificates.

    Hopefully the system will continue to pump enough heat to keep the house warm. In the mean time, while traveling, I have been compiling a document with all the recorded data and experiments that the support team has suggested. It seems to be a directional thing in that it works well when reversing valve is set to cooling and the the refrigerant flows through the air coil, TXV and filter in the opposite direction. I think we can rule out the compressor and reversing valve. The rest of the system is supposed to be bidirectional but I have experienced issues in hydraulic systems where the failure acted like a check valve. Restricting in one direction only. So we will see, you always learn a lot more sorting out a problem.
  8. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Mark makes good points - assuming the mfg has properly documented charge requirement, weigh in is best. It is still a good idea to let everything settle down (running in steady state 15-20 minutes) and then verify proper superheat and subcool with decent instruments.

    As to evacuation I regard 500 microns as absolute max. I prefer my guys to attain 250-300.
  9. Dan Dillner

    Dan Dillner Member

    Well we are back from our winter get away. The system ran flawlessly with the exception of using more power than we should be using. We had a very cold winter here in the north country and I remotely monitored the system performance closely and have collected some in interesting data that will help me size the next unit. Nothing like real data. Basically the 5 Ton unit extracted 10KBTU when running but consumed 3kw. Consistent with what I detailed in the earlier posts.

    We now have the Mfg Engineer working up a plan that hopefully will get this unit working to it's potential so we can remove, sell and replace with a much smaller unit.

    In the mean time I am starting to look at various systems and have some questions that some of you might have opinions on.
    Looking at the 2 stage 2Ton CM Tranquility 27 or 30. Anyone know what the key difference between the 27 & 30 is? There is quite a bit of difference in price.

    I also have been using a simple Honeywell programmable Tstat and want to upgrade to a ecobee.. Any thoughts Pro or Con on the ecobee?

    Thanks, Dan
  10. Stickman

    Stickman Active Member Forum Leader

    I believe the difference between the 27 and the 30 is the SEER rating. Both are now listed under CM's obsolete products category. Not sure how significant obsolescence is though. There is a digital version of the 30 that's a live unit. This one has communicating controls and an internal variable speed loop pump. Lots of info here:
  11. Dan Dillner

    Dan Dillner Member

    Thanks for the link Steve, the CM 30 that I have been looking at is the digital. I am mostly concerned with heating so I compared the COP and they appear to be the same. Must be the digital controls that are the big difference.
  12. Stickman

    Stickman Active Member Forum Leader

    I think it's a 4-wire cable between tstat and unit versus the traditional wiring. The CM tstat allows fan speed adjustment and does deliver some operating data too, but not as much as a WEL-type setup would. Other than that, I guess the merits of VS pumping might warrant attention.
  13. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Geo heat pumps are not SEER rated, since they do not fluctuate so much under changing outside temps...Usually it is the EER rating in low stage what CM is trying to represent with the model indication.
  14. Stickman

    Stickman Active Member Forum Leader

    Thanks for the correction Doc. Been spending time reading on non-geo HVAC as well, and forgot the difference existed between EER and SEER.
  15. Dan Dillner

    Dan Dillner Member

    OK short update on my system. The mfg (Geocool) decided that the system should be returned, they think the TXV valve is what causes the system to work in Cooling but not in heat mode. So I have shipped the system back to them and they will replace with a new unit. Since I really only need a 2 To system (my mistake), I will now sell the new in a crate 5 Ton Geocool when it arrives on Craigslist and order a 2 Ton system. I am looking at the CM 27 or 30 and trying to decide if the 30 is worth the extra $1500.

    We have been comfortable with a single stage unit that was putting out about 10K Btu but using the power of a 5 Ton unit :(

    We now have empirical data that indicates 1 Ton would be adequate at -10F. We will be using it in a open well system that was designed for 5 Ton.

    So my question is the CM 30 digital worth the difference over the CM 27 which is still available.

    The next question for you guys would be what Tstat would you recommend? I would really like to have remote control and have been looking at the ecobee.

    Any comments from you guys would be appreciated.

    Thanks, Dan
  16. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Yes ecobee. doesn't matter which heat pump. If you buy the 30 or the 22 (vs 27) you can buy the service tool and have a little better info if something goes wrong.
  17. Dan Dillner

    Dan Dillner Member

    Thanks Joe, I bought the 30 and will look at getting the tool and using ecobee in stead of using the ATC32U02. I am looking forward to setting this up and see how it performs.

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