Pennsylvania Geothermal not staying engaged

Discussion in 'Maintenance and Troubleshooting' started by Rankali, Dec 30, 2020.

  1. Rankali

    Rankali New Member

    I am having an issue where the compressor on my open loop Carrier geothermal (Installed 2005) isn't always engaging. The issue has been going on for about a year. Here is the quick run down:

    January 2020 heat stopped working. Got a compressor lockout error code which indicated several items: CXM Board, thermistor, low water flow, low refrigerant. Called service company recommended by Carrier. They came out in the beginning of March and changed the CXM board and thermistor and checked the refrigerant pressure (which they said was ok). Problem came back in a day or two. They had no other ideas on what to do.

    By now it was early April and we didn't need the heat. The air conditioning worked fine which I think points to either low water temperature, low water flow, or refrigerant.

    In May I had a different company look at it. They were also going to flush it but when he got here he said it needed a special type of connection and left and I never heard from him again.

    I ordered a flush kit and flushed calci-free through it (its a standard 1" connector). The water came out as a dark blue. Ran the unit all summer with no issues.

    When heat was needed, I was having the issue again. Sometimes it works fine, other times it randomly cuts out and the blower & well remain engaged (I leave the breakers for emergency heat off). I can turn the heat off and then back out and it might work for a couple of days or a week. Sometimes I have to turn it off and on several times to get it working.

    Yesterday I flushed it again with vinegar. The vinegar ended up light blue but otherwise clear. Water flow is around 5.5-6 gpm which is low but about what it has operated at the last 15 years.

    I am going to try and use the dealer listed on this site for service post COVID to figure this out, but am trying to get through the winter without it and will rely on the pellet stove for heat.

    I am looking for ideas on what it might be. I think #1, I need to get that water flow to 8 gpm to give it 2gpm per ton. Is it better to have to valves, 1 for each heating stage? The unit currently only has a single Taco valve with a 6 (or 8?) gpm flow restrictor on exit.

    Basic Information:

    1) Where you live - PA
    2) Heat loss/gain calculations for your home - TBD
    3) Brand, size (model) and type of heat pump - Carrier 50YDV049JCB301
    4) Type of loop field (open/closed/vertical/horizontal) size and design parameters - Open Loop, Well depth ~250 feet
    5) Average cost/Kwh of electricity and consumption - 10.3c/kwh; December 3494 kWh, avg temp 38F
    6) Entering and leaving air temperatures (EAT, LAT) measured immediately upstream and downstream of the heat pump, TBD
    7) Entering and leaving water temperatures (EWT, LWT) measured at the heat pump(s), 53f in, 46f out. The LWT is high compared to several years ago when it was around 41.
  2. Rankali

    Rankali New Member

    I got a pressure gauge for the geothermal yesterday and was able to run some more diagnostics. I was able to get the unit working, I'm just not sure if the root cause is corrected or if the system will shut down again.

    I measured the pressure at the water inlet of the geothermal and it was 15-20psi. This resulted in a flow of about 4gpm as indicted on a flow meter at the outlet to the well. I adjusted the pressure regulator inline to the geothermal to 40 psi. This resulted in a pressure of 38-42 psi into the geothermal and 36-40 psi coming out of the geothermal. This brought the flow of the unit to 6 gpm. I did some measurements:

    House 46-56 PSI - Franklin CP Subdrive (not sure if this pressure swing is normal, but its always been like this)

    -HWG Active

    -Geo In: 38-42 PSI; 51F* *my hvac therm broke (probe separated from sensor and exposed wire upon removal from Geo Out) on this measurement and I had to use a digital meat thermometer at a sink

    -Geo Out: 36-40 PSI; 42.6F - Temp is good for this measurement
    Note: These were within a few minutes of runtime, I think it would have been better to measure after an extended run time.

    -Air In: 64.5F
    -Air Out: 85.6
    Note: These are with the broken hvac gauge but are probably close

    I am seeing a 2PSI drop, which theoretically translates to 8.3gpm but the flow meter shows 6gpm. Also, I confirmed a 8gpm flow restrictor is in place right before the outlet to the well. From what I can find, it appears restrictors are rated at 60PSI for household use so by running at a lower pressure, my flow is less. Ideally, what I think may be needed is a 10-12gpm restrictor which would allow me to adjust the water pressure lower but still have a gpm flow. I may boost my pressure closer to 60 for now and see if I can get close to the 8gpm.

    The other thing I noticed is that about once every 1/2 hour or so, the compressor seems to stop for about a minute. I've attached a picture (if it works) showing the amps drop, and then it starts back up a minute or so later. Is this normal, or is this still an issue? I will monitor the system to see if it remains operational.

    Edit: For comparison, measurements from 02/2012:
    -Water In: 51.8
    -Water Out: 41.1
    Air In: 64
    Air Out: 87
    Pressure Drop: 2PSI

    Attached Files:

    Last edited: Jan 24, 2021
  3. Rankali

    Rankali New Member

    Worked for a day and a half but it locked out with FP4 error code again....really not sure what it can be at this point. Puron(tech said it was ok)? TXV?
    Last edited: Jan 25, 2021
  4. gsmith22

    gsmith22 Active Member Forum Leader

    It used to be that Carrier heat pumps were just rebranded Climatemaster heat pumps. I don't know if that is still the case but pretty sure that was true back in 2005 when yours was installed. Its certainly possible you may find more diagnostic info for the equivalent Climatemaster heat pump (if you can figure out what that was).

    I'm not sure I understand how you flush an open loop system - disconnect the water connections and hook up an apparatus to only flush the heat pump? I also don't understand the significance of the color - did you flush with something blue or was it initially clear and came out blue after flushing?

    Typically if something works fine for 15 years and then stops, you want to know what changed. Since everything but low water flow was presumably corrected/investigated in early 2020, water flow is probably the place to start. In a heating dominated climate, low water flow for A/C use is probably a non issue so that could make sense with why it worked fine during the summer and then reared its head in the middle of winter again. Assuming there is nothing different about your well pump now vs then (I can't tell but sounds like the well pump is shared between domestic water and heat pump?) buildup of crap in the water system might be limiting flow when most needed. Do you have hardness, iron, etx. in your water? Could it have gummed up the taco valve on the outgoing side restricting flow more than it should? This is probably where I would start.
  5. Rankali

    Rankali New Member

    It is a rebranded Climatemaster and I have found some good information from both sources.

    For flushing the system, I disconnected the water inlet and outlet of the unit and hooked a submersible pump (inside a bucket) to it. I ran calci-free through it. A month or so later, I did the same but used white vinegar. The liquid was clear going in, but became blue. I am thinking its from clearing the scaling of the inside.

    Its possible its a water flow issue and that makes sense with it working in cooling, the part that confuses me is that it could be fine for a 24-36 hour period where it runs a lot, but then sites several hours and goes into lockout when it tries starting. It seems like its an intermittent issue. I see about 6 gallons per minute going through the line which 'should' be enough to work.

    The water is fairly good but its always possible after 15 years something is restricted. I don't have a good way to flush the outlet and would need to cut copper and replace the taco valve and/or flow restrictor. There is a rusco sprial filter in front of the geothermal. The well is a shared well.

    Should I see if I can get a 8-10 gpm flow instead of the 6gpm?
  6. SShaw

    SShaw Active Member Forum Leader


    A FP error code indicates the water temperature is too low, which could be caused by insufficient water flow. More importantly, the install manual for the unit states you need a minimum of 8 GPM with EWT below 50-deg, whereas you say you are getting only 6 GPM. From the manual:

    NOTE: When EWT is below 50°F [10°C], a minimum of 2 gpm per ton (2.6 l/m per kW) is required.
  7. gsmith22

    gsmith22 Active Member Forum Leader

    so maybe two issues that caught up with an older install - marginally enough water flow in the first place but on a new machine was still acceptable to allow unit to operate. go 15 years and unit has built-up stuff on the water side (due to open loop water) making a marginal original installation now non-working. So yes, get water flow higher from pump but it also seems like you should maybe keep flushing until no more "blue water" comes out.
  8. Rankali

    Rankali New Member

    The discussion here had me check a few things. The well pump was changed out about a year ago, it went from a franklin subdrive 75 to a subdrive 100 with stronger pump.

    Ive noticed the pressure change in the house because its a constant swing. After your comments I did some reading and im not supposed to see a 10-12 psi swing. I checked the pressure tank and noticed two things 1: The well installer probably should have gone from a 4.5g pressure tank to an 8g tank and 2: The pressure in the tank was 20psi, it needed to be 35-40.

    I charged the tank and will run the system tomorrow and see how it goes. The pressure swing was cut in half so if nothing else there is that.
  9. gsmith22

    gsmith22 Active Member Forum Leader

    something related to this new pump is the issue. Franklin subdrive is a variable speed well pump, correct? so that should have a constant pressure. As I understand it the whole benefit of the variable speed is the constant pressure varying the pump speed to match water flow demand (probably could have used a cycle stop valve to accomplish constant pressure at much cheaper long term cost but I digress). So if you have a variable speed pump that will provide exactly the flow you need, why aren't you getting that?
  10. Rankali

    Rankali New Member

    The adjustment of the pressure tank brought the variation of water pressure within spec. The Geothermal was set to come on last night when the house temperature dropped below 64 (the pellet stove providing most of the heat). It turned on at 4:49 AM and after 1-2 minutes the compressor cut out. I shut it off this morning and turned it on at 10:35 and it has been running the last 1/2 hour. PSI In/Out are within spec, its sitting at between 6-7 GPM, water temp is in is 52-53 degrees, its providing the proper heat rise, etc.

    What would cause an issue right at start-up? It seems like if it starts, it can stay running fine, but when it stops, it might not start back up. I will let it run for a while to see if it cuts out while operating, or if its only on a start up sequence that it faults. I can't wait until post covid when I can have someone in to look at this.

    I called Climatemaster and explained the situation to them and we went over a few things. The system is basically operating in spec when it is running, they do recommend a better water flow though. They did say that the compressor should not be turning off every 30 minutes or so, it will only turn off when it has run for 4-5 hours straight to take a small break. They also said the tech should not have checked the refrigerant level without exhausting all tests first. It could possibly be a TXV valve, but needs a full diagnostic. They said to have the next tech call them and they will guide the diagnostics.

    I thought it was nice of them considering it was a rebadged Carrier unit and 15 years old.

    The unit has been running the last 2 hours but still does the drop out of the compressor periodically for a minute or two. My plan is to not use the unit unless really needed, and then only to bring the temperature up a few degrees. The pellet stove can handle the bulk of the heat until the temperatures get into the single digits, then it needs a little help (I will run a space heater or two in the day).
    Last edited: Jan 29, 2021
  11. SShaw

    SShaw Active Member Forum Leader

    I can't say for sure why it would cut out right away, but any fault code from the system might help determine the cause.

    As I noted above, the installation manual for your system says it requires 8 GPM minimum for EWT at 50-deg, so 6-7 GPM is outside the specification. The unit could have locked out on one of the protection sensors if the water flow was insufficient.

    You should make changes to get the water flow up to 8-10 GPM. Flow is what matters. The incoming pressure doesn't matter as long as you get the flow.
  12. Rankali

    Rankali New Member

    Once I can get someone in, I will have them take out the flow restrictor that is in place and put a 10gpm restrictor in to increase the flow. If I have good flow, I can reduce the pressure to save on some well pumping.

    I checked the installation manual at the unit, and 1.5 gpm/ton seems to be in spec as the EWT is 51-52. There isn't much margin though as the water temp is close to 50 but not quite there. Flow will help and make it more efficient, but I'm not 100% it is the ultimate culprit here. I wont be able to know for a while though when I can get someone in.
  13. gsmith22

    gsmith22 Active Member Forum Leader

    wells that share domestic water and open loop geo end up not being good at either. Domestic water generally needs high pressure and low to moderate flow. Open loop geo doesn't need high pressure but good flow. Clearly, your issues began at the time of the well pump change so I would look to that. What I don't understand with all of this is why you need the flow restrictor. On a typical non-variable speed well pump with shared domestic and geo, that makes sense because you are probably pushing more water than necessary through the heat pump (because the pressure switch is often set up at 40/60 psi for domestic use). In this situation, a valve is often put on the outgoing water line of the geo to adjust flow from the pump so they don't mess up the domestic water. But with a variable speed well pump, why can't it just produce what you need - no restrictor valve? could the combo of the variable speed well pump and the restrictor valve be the issue? Doesn't the pump just ramp up to what is needed as geo, faucets, laundry, shower all get turned on?
  14. Rankali

    Rankali New Member

    I am not great with plumbing, but I think without the flow restrictor the well will try to pump as much water that will fit through a 1" pipe. At 20 PSI its 26gpm, at 60 PSI, its 47gpm. The well is rated at 25-50gpm, but I don't think the pump can do more than 12gpm at 60PSI.

    The pump ramps up to maintain a constant pressure, but I think all of the fixtures have some sort of flow limit in them.
  15. gsmith22

    gsmith22 Active Member Forum Leader

    There are others that understand this better than me, but it sounds like you need a pressure reducing valve on the line from the well to the geo to get the pressure down to like 15-20psi (assuming something like 40 to 60 psi in front of that valve for domestic use). then you have to have a modulating valve that opens and closes (typically on the geo out line) that the heat pump opens when it turns on and closes when it turns off. I would think that somewhere (probably after the modulating valve) you also need a valve to control flow because it seems like you are still going to get too much flow. So when heat pump turns on, it opens modulating valve, well pump sees a pressure drop and begins to pump, flow valve limits gpm through this system. Based on what has been described, it seems like you have the modulating valve on the geo out line and flow valve (not sure where) but not the pressure reducing valve? I realize that may not be causing your issue, but the high pressure on the heat pump can't be good for it either. I wonder if the modulating valve that opens/closes with heat pump operation could possibly be opening too slow, heat pump turns on and not enough flow (cause valve isn't open or open enough)? maybe clogged up like the heat pump was with "blue water". a sticky modulating valve may explain random not turning on initially conditions. I dont' know what an error code for something like that is. Maybe you can watch the valve to see its position and check when compressor starts?

    If you read threads on this, your geo unit is going to use more water than domestic use. So the setup for best efficiency is to set the well pump up for geo (at lower pressure) to use less energy, then after pipes split from geo, add in another jet pump and pressure tank to bring pressure up for domestic. there are obviously many ways to skin a cat, but your setup, while common, is bound to make the whole system very inefficient because of the high pressure that the well pump spits out only to put backpressure on it to lower for geo use.
  16. Rankali

    Rankali New Member

    Just wanted to close this out if anyone had the same issue. I had the local company come out and they did about $1200 in"work" changed a few capacitors added freon but I suspect it was fine, and fiddled with it. They then said I needed a new geo unit for $25k.

    I changed the Taco valve (the orange head) on the unit and it worked splendidly. The valve failed in another 12 months so I just put another one on it.

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