Geo Newbie with a couple questions

Discussion in 'General Discussions' started by Todd, Mar 25, 2018.

  1. Todd

    Todd New Member

    Hello,

    I recently purchased a 2400 sq ft ranch home with 1300 sq ft conditioned basement in NE Indiana. It has a WF Premier 4.5Ton package unit in the basement that was installed in 2001. I have an open loop system and 4" submersible well along with what appears to be a 40-50 gallon pressure tank. I am unsure of the HP rating of the pump and the actual well depth, but most wells in this area are anywhere from 65-120 ft deep.

    Only the Geo unit and outdoor spigots use the well water. All home water used comes from the city supply.

    Overall, this system seems to heat the house just fine. I have only owned it for 45 days and we are in a full remodel of the home, so I have not been in the home to check operation and comfort daily.

    I have asked the original installer (also the same company that has serviced the unit for the last 17 years) to come out and educate me on how the system is configured (pressure tank cut-in/out settings, GPM setting of flow through unit, Taco valve operation, etc) I told them I just needed an education and also an opinion if it should be replaced soon and what they recommended. They did not seem to care to talk to me on the phone and never called back, so I thought I would start here with my basic questions and find a good company to service/replace this unit in the future.

    1. Currently, the well cut in pressure is roughly 45 and cut out is almost 75. The 1st stage Taco valve is very noisy above 55 PSI and the 2nd stage is noisy above 45 PSI. It seems to me that this pressure is excessive and if I am understanding correctly you only need 12 PSI or so for the unit to operate correctly. Should I simply adjust the cut in/out pressures down to eliminate this noise or is a pressure reducing valve recommended? I obviously need decent pressure for outside watering as well, so looking for a solution here. I want to get rid of the turbulence noise going through the Taco valves.

    2. How do you measure GPM flow of water through the unit? On my system water comes from the pressure tank, to an iron filter, through the unit, through a ball valve leading to Taco valves, another ball valve after Taco valves, and then discharges through PVC exiting the home with no ability to collect the discharge water for measuring. There is no flow gauge or ability to measure water exiting the Taco valves. The ball valve after the Taco valves is closed about 1/2 and I assume this is to regulate either flow and/or pressure, but I have no idea how much water I am flowing. Fro what I understand I need about 7 GPM or so of water flow for the open loop system assuming 50F EWT and 4.5 Tons. If I am flowing too much water I assume this will make more noise in the valves and waste energy? Too little water will cause the system to freeze up/lockout? Does varying pressure also vary the flow?

    3. All in electric costs are about 11 cents per KWh here, but natural gas is fairly inexpensive also. Assuming the well water quality is good does it make sense to continue with Geo? I also am considering adding solar panels on my roof in the future which adds to the advantage of Geo. My roof pitch, area, and direction is ideal for solar. I am just trying to decide if Geo is still the way to go and if the open loop system is reliable. I like efficiency, but will pay more for reliability and simplicity. I have always had GFA with standard A/C split system in prior homes.

    4. Finally, assuming I stay with Geo, what is the current preference of brand. I have read about the series 5 and 7 WF and the CM Tranquility 30. The CM appears to have a little better technology interface for the user and also has an internal automated water flow valve for open loop systems like mine. The WF is manufactured 25 miles South of me and seems to be popular around here.

    Thank you!
     
  2. arkie6

    arkie6 Member Forum Leader

    As far as flow rate goes, what you want is about a 5 degree F differential temperature across the water-refrigerant heat exchanger coil under full load. This is typical for a closed loop system like I have flowing ~3 GPM per ton. With an open loop system you can typically get by with a lower flow rate which will equate with a higher differential temperature.

    And yes, your water pressure cut-in and cut-out seems higher than necessary for this application. A cut-in of 20 psi and a cut-out of 40 psi should be more than sufficient for the heat pump.
     
    Last edited: Mar 27, 2018
  3. Todd

    Todd New Member

    Thank you for the reply. I will adjust down the pressure tank. Will flow rate decrease with pressure decrease?

    Not sure how to measure temperature difference between refrigerant and water heat ex changers. I believe the CM Tranquility 30 has built in monitoring of all the parameters and maybe the WF 5 and 7 does also. I have a very nice touch screen Honeywell unit, but it has no internal information concerning the Geo unit.
     
  4. arkie6

    arkie6 Member Forum Leader

    Yes, if you have a fixed flow orifice, then reducing the pressure will reduce the flow rate.

    You need to measure the Entering Water Temperature (EWT) and the Leaving Water Temperature (LWT) to determine the differential temperature across the coil. You likely have Pressure-Temperature (PT) ports in the brass elbows where the water lines enter and leave the unit. Remove the cap off these ports and insert an HVAC or meat thermometer with small diameter probe into the PT port to take a reading.

    You can probably find a video on youtube that shows how to do this.

    I did a quick google search and found this thread that has some photos of the PT ports near the bottom of the page.:

    https://www.doityourself.com/forum/...eothermal-heat-pump-massive-energy-usage.html

    If you get a pressure gage that you can insert into the PT ports (you can find these on ebay - search for geothermal PT port), and you have the heat pump manufacturer's specs for the pressure drop across the coil, then you can determine flow rate that way as well.
     
    Last edited: Mar 26, 2018
  5. Todd

    Todd New Member

    Thank you again for the information.

    According to the manual I should be flowing about 1.5 GPM per Ton of water (open loop) which would be 7 GPM for my 4.5T unit. The manual then states at that flow rate I should see a 10-17 degree drop in water temperature.

    As for pressure, it varies greatly with water flow (which I can't measure easily.) At 6 GPM it states 2.1 PSI, 9 GPM 4.3 PSI, and 12 GPM 6.8 PSI difference. It appears that setting it for temperature range will be the easiest. If the caps are removed and a meat thermometer is inserted, what keeps the pressurized water from spraying out around the thermometer probe? The pressure probes I see listed have a cap that screws down after the probe is inserted. I don't see that available for temperature probes.
     
  6. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Usually, the rule of thumb is to have a bout 1.5 gpm flow in an open system, and 3 gpm flow in a close system. Which equates to about a 10-12 F degree difference between entering and leaving water temperature for an open system, if your refrigerant circuit operates nominally.

    You don't want to drop your leaving water temperature below 38F, then you get freezing inside the heat exchanger.
     
  7. arkie6

    arkie6 Member Forum Leader

    You measure the pressure drop across the water coil and determine the flow rate from that. Say you measure 24 psi on the inlet side and 20 psi on the outlet side. That means you have a 4 psi differential across the coil which equates to just slightly under 9 GPM flow rate based on the numbers you posted, i.e. 9 GPM = 4.3 PSID. But note that those numbers assume a clean heat exchanger. With you being on open loop water, you likely have some mineral deposits which may make for more pressure drop for a given flow rate, i.e. 9 GPM may actually be 4.5 PSID or higher.

    The PT ports have an internal rubber seal with a small slit. With the cap removed and no probe inserted, there shouldn't be any leakage or at most a drop or two. You may get a few drops of leakage when you initially insert or remove the probe, but the rubber insert is designed to seal around the probe whether it be a pressure probe or a temperature probe. The caps you see on the pressure probes are just there to protect the probe when not in use.
     
  8. Todd

    Todd New Member

    Thank you both for the responses. I will get a pair of thermometers from Walmart and test/adjust the temperature difference. I will keep in mind no less than 38F exit temp to avoid freezing. I assume as water flow decreases in heating mode so will the exit temperature.

    This unit has been serviced a couple times per year checking the temps and pressures.

    On 6-30-17 this was recorded: EWT 56 / LWT 69, EWP 52 / LWP 50, RA 72 / SA 52
    On 10-31-17 this was recorded: EWT 53 / LWT 46, DT 28, SA 97, RA 68

    Appears to be working for heating and cooling.
     
  9. arkie6

    arkie6 Member Forum Leader

    You generally don't want to use two different thermometers for this measurement due to potential inaccuracies between the thermometers. Since you are looking for a relatively small difference in temperature between the two readings, the preferred method is to use one thermometer for both temperature measurements.
     
  10. arkie6

    arkie6 Member Forum Leader

    Based on that Entering Water Pressure (EWP) and Leaving Water Pressure (LWP) difference of 2 psi, it looks like you had approximately 6 GPM flow through the coil based on the numbers you posted above. That is a little below your desired flow rate of 7 gpm, but not much. If you were to reduce your water supply pressure, you would likely need to open up the downstream ball valve a little bit more to raise the flow slightly. A water differential pressure of ~3 psi should give you around 7-8 gpm flow which would likely result in a water differential temperature of 10-12 deg F.
     
  11. Todd

    Todd New Member

    Thank you again - I appreciate the help. I calibrated both thermometers and then put them in the PT ports. I adjusted the well down from 75/45 to 65/35 (did not have time to fine tune it further.) I started fully open on the downstream valve and had about a 5 degree differential of 52/47. I closed the valve incrementally several times until I achieved EWT 52 / LWT 42. The LWT would rise to 43 as the pressure in the tank increased to it's high cut off and then went back down to 42 as it approached the low cut off. Tank is a 85 Gallon Well Rite and time from well cut off to well cut in was 3 minutes and 25 seconds. I did not measure how long the well pump ran after low cut in, but I estimate it was probably 6-7 minutes of run time before cutting out again.

    Next time I will use a single temp gauge as you suggested.

    Now, if I wanted to maintain the higher water pressure for outdoor watering and also supply the geo unit with proper pressure and flow, would it make more sense to simply install a pressure regulator on supply line going to the unit? It seems that adjusting the pressure to a constant of maybe 20-30 PSI (or whatever it takes to get my desired temperature/PSI spread) and opening the outlet valve fully would provide a more consistent EWT/LWT spread and probably save water also.

    I have read the never ending arguments for a CSV or variable speed pump, but neither are appealing to me. It seems like a pressure reducing valve before the geo unit would be the most cost effective and most simple solution.
     
  12. warmbrus

    warmbrus New Member

    Hi, I am new to geothermals and not an expert. My issue is that I have replaced two heat exchangers and the copper pipe to the heat exchanger is very thin. I live in Kentucky and my system is open loop on a well (pump and dump). I have a Carrier unit which is made by ClimateMaster and I believe is same as the CllimateMaster Tranquility. The Carrier model is GT-PX 50YDV049KCK301. It is a 3 1/2 ton unit with scroll 2 stage compressor. The pressure switch on the well is set 30 psi to 50 psi. When the water pressure is near 50 psi it sounds like cavitation in the Taco 556 control valve. However, I am thinking my issue is particulates in the well water is eroding the piping and heat exchanger. Does anyone have info on external/indirect heat exchanger sizing information. The cure may also be a water filter if anyone has information on sizing a filter or knows who can help. Thanks.
     
  13. Todd

    Todd New Member

    I thought I would reply and update. My Old 2001 WF is working well, but I have decided to put in a new Climatemaster TE30 once the remodel in the house is done due to the 30% credit and the fact that everything else in the house is new and I am hoping for little maintenance in the future. We have already put in a new variable speed well pump and I like that much better than the old pump.

    A few weeks ago a gentleman saw my HVAC contractor at my house and stopped in to talk to him. The contractor had just installed a TE30 and the customer was unhappy with the noise it made. He wanted the contractor to move it into the garage due to the noise. After reading the Climatemaster manual and reading about noise and experiencing the same noise with my WF I suggested to both of them that a 30 PSI reducing valve be installed before the unit. The contractor installed it and the noise went away. It appears that when the internal valve in the unit closes more than a certain percentage there is considerable noise made in the valve. Even though my variable can make 40-100 PSI I am installing the valve as well. I want a quiet machine.
     
  14. nc73

    nc73 Member

    You'll have to let us know how the variable speed well pump hold up long term. I've heard they only last a few years.

     
  15. allencp

    allencp New Member

    I've have a Grundfos constant pressure pump 15SQE10-250 with a CU301 controller that was installed in 2008. Had one CU301 controller to bite the dust. I sure do like the steady 50PSI. Like others, I have a water reducing valve set to 25 PSI and use a globe valve to set the flow rate.
     

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