Ontario 5 ton Geo running 24/7

Discussion in 'Maintenance and Troubleshooting' started by Maurice Sabourin, Oct 21, 2015.

  1. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    HVAC techs are trained to take your money and sell new stuff. That is why I retired. I can now make honest deals.
     
  2. Maurice Sabourin

    Maurice Sabourin Newbie but learning quicly...


    Thanks mark, that makes me feel so much better...
     
  3. geoxne

    geoxne Active Member Forum Leader

    If you look up in the pressure drop tables on pg 37 of the IO manual I previously posted, 2psi pressure drop with both HPs running will get you 7.5 gpm for the R-65 unit and published optimal flow of 14 gpm. The R-25 units flow under the same condition is just over 6 gpm with published optimal flow of 8gpm.

    I can not be sure which unit has a 5F drop or which has 4.5F drop so I'll do the math for both at 5F drop source side drop.
    R-65 7.5gpm x 5dt x 485 = 18,188 btu/hr = HE( should be at proper flow around 34,798

    R-25 6gpm x 5dt x 485 = 14,550 but/hr = HE(HAB) should be at proper flow around 14,644

    Your 5 ton unit does not have enough flow when both units are running and is low on refrigerant.
     
  4. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Low R = leak. Yikes.
     
  5. Maurice Sabourin

    Maurice Sabourin Newbie but learning quicly...


    Thank you geoxne.
    If i understand your last sentence correctly according to your calculations, the 5 ton is low on refrigerant?

    Maurice
     
  6. geoxne

    geoxne Active Member Forum Leader

  7. Maurice Sabourin

    Maurice Sabourin Newbie but learning quicly...

    Thank you

    May I quote your calculations and send them to the installer so he can come and fix the problem?
     
  8. geoxne

    geoxne Active Member Forum Leader

    Yes, if you ask him why the tech didn't do the math while he was there. Also, don't over look the low flow issue. Even if they weigh in the correct charge and there is no refrigerant leak, the unit will probably lock out on low pressure at lower loop temperatures.
     
  9. Maurice Sabourin

    Maurice Sabourin Newbie but learning quicly...


    I have sent off a third email to the owner of the company. He as not replied to my first one yet...
    I hope to hear from him tomorrow.

    What is the procedure to fix this problem it it turns out to be a leak?
    These units are barely 4 years old, and the problem started over a year ago, I am not happy about replacing major parts or opening up a unit that should be relatively maintenance free for 10 years or more...

    Unhappy customer to say the least.
     
  10. geoxne

    geoxne Active Member Forum Leader

    Find the leak and fix it. Sometimes the fix is replacing a major component, sometimes not. Sometimes the leak is so small it is hard to find. Most manufacturers discourage repeated unnecessary attachment of manifold gauges as refrigerant can be released every time. Overtime enough to effect the operation of the unit. This is why we are taught to ONLY look at the refrigerant circuit AFTER problems with the water and air side are ruled out first.

    Also, my calculations for flow were based on 15% methanol. I just noticed you have glycol. That would decrease your flow even further.
     
  11. mrrxtech

    mrrxtech Member

    Maurice,
    I check my loop pumps running by putting a hand on each motor as I mentioned earlier. I do this often so I will notice if something changes, like vibration or the motor temperature.

    Have you checked the loop pumps by feel to see if they are running normally on both units? It's possible that one pump will provide enough flow to prevent a unit trip but lower the performance of the unit.

    I hate to ask the obvious, but sometimes it pays off.
     
  12. Maurice Sabourin

    Maurice Sabourin Newbie but learning quicly...

    Both the flow centers are working properly as far as what the tech said.
     
  13. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Just make sure that the delta T on the water side is not recorded when only one heat pump is running, which can throw the assumptions here off.

    The fact that the flow centers steal water flow from each other and drop to 2 PSI delta P when they both run at the same time brings an issue with the loop/header size to the consideration, namely that having 2 flow centers with 2 pumps clearly indicates that they did not look at efficient flow and pumping.

    Having only half the specified flow is clearly out of the design envelope, that was why I had asked you for the model numbers of the pumps. Your picture showed a dual pump flow center for a 2 ton unit, which is certainly overkill in my book, and it still not doing the job. It does not explain your drop in heat capacity this year compared to last years running fine.

    Also need to know if delta T was measured in first or second stage!

    So we need to have delta T and PSI over the coil in first and in second stage when only one unit is running, make sure no flow goes through the second heat pump at that moment. Please confirm that this was the case when the technicians did the measurements!
     
  14. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    The numbers look better when they are taken individually, that means only one pump running at the same time.

    The source in (EWT) should be identical, but are reported different by a full 3 degrees, suggesting that the tech recorded one, which was taken heat out of the loop, and some times later recorded the other heat pump. Again, no word if 1st or 2nd stage was running when they recorded it.

    Again, I would not bet on low refrigerant ......just not yet!
     
  15. mrrxtech

    mrrxtech Member

    Maurice,
    To trouble shoot the 5 Ton Unit Running Continuously:
    When you have time, and the house temperature has satisfied the thermostat (or lower the thermostat setting to satisfy the thermostat).

    1) Check Y1 at the Unit is at 0 vac.
    If Y1 is at 24vac at the Unit you have a wiring or component issue causing a Sneak Path for 24 vac based on several thermostats being used with the same results. The problem will be in the Unit wiring or circuit board component.
    2) If Y1 is 0 vac as it should be, the Compressor Contactor (relay) should be dropped out with the compressor de-energized.
    3) If the Compressor Contactor is picked up (Compressor running), the 24 vac at the Contactor coil is being supplied from a sneak path, component failure or wiring error.

    I don't expect the contactor for the compressor to be bad since it would fail de-energized & open, Compressor de-energized.
     
  16. jk96

    jk96 Member

    Way oversized and many zones was creating problems for us. Docjenser suggested zone bleeds recently and it made a huge difference. Before we had run times as short as 8 minutes. As soon as the units shut down another zone would call and have to fire back up. I had to add a 3 degree swing on the t-stat to help the short cycling. It seemed like they were constantly running even though we were oversized. After docs suggestion I moved the t-stat swing back to 1.5. I tracked performance last night for 4 hours, 7:30pm to 12:30am with outside temps at 35 falling to 31. We had a total run time between both units of 53 minutes so things are looking much better.
     
  17. geoxne

    geoxne Active Member Forum Leader

    Maurice
    IF the posted pressure drop of 2psi is correct.
    AND IF my flow calculations based the above info is correct.
    AND IF all pumps are UP2699.
    AND IF all pumps are working.

    That is a lot of IFs and all need to be verified, but would mean your total system head (both units running) is 55 to 60 Ft/Hd at 13.5gpm based on published pump curves. This is a very high head and IF correct would indicate something is wrong with piping design or sizing or configuration either inside or outside or both. Or there is an obstruction or malfunction in the piping or loop system.

    Diagnosis will require a step by step methodical approach with intimate knowledge of system components and the calculations with correction factors for glycol%, required to compare installed design to actual performance. Doc is correct, Psid needs to recorded with each unit running individually and then together and EWT & LWT needs to be recorded at confirmed stage2 operation, again first with each individual unit running and then together.

    I am not one to speculate but I am suspicious the original source was piped and configured with no calculation for head and flow. Also, the later installation of a second flowcenter just tee'd into existing piping was done without regard to head and flow. If they prove me wrong I will be happy for Maurice. It could be as simple as inadequate antifreeze protection or a pinched pipe at the foundation after trench settling and so on.
     
    Last edited: Mar 5, 2016
  18. Maurice Sabourin

    Maurice Sabourin Newbie but learning quicly...

    the
    the pumps model numbers...
    the white pumps is on the 2 ton, geofinti flow center type UP 26-116U

    the silver flow center is on the 5 ton, Hydro Flow, type 26-116F

    origanaly they had installed one flow center the white one and an extra pump on the five ton.

    also, there is a total of 36 90 degree elbows between the loop and the HP's, that must slow the flow a little???
     
  19. geoxne

    geoxne Active Member Forum Leader

    Yes.

    The one thing I am stuck on is the first 2 years you say the 5 ton unit performed as you expected. Did they install the second flowcenter after it started misbehaving? Keeping in mind that any flow issues would be most apparent in your system as loop temperatures drop below a certain point (when you need it most).
     
  20. Maurice Sabourin

    Maurice Sabourin Newbie but learning quicly...

    Ok, as i am sure you are all aware i am not an HVAC pro, not even close. i am very mechanically inclined and understand most of what you are all saying...
    I can follow your instructions and do all the checking and testing myself...
    some of the tools and instruments i will need are on their way. should have them all next weekend

    Using the reports form the techs as a give may throw us off because they write the reports in the truck before they leave, they dont take notes as they work...
    my memory is very bad... so if theirs is slightly off, you can imagine the results. they could also be masking some of the numbers...

    I am very much starting to believe the the whole system is badly designed.... so 43k$ down the drain...

    I soon as the original installer gets back to me i will know my next step.
    if the installer does not cooperate i will ask one or some of you to give me step by step instructions to check everything. Basic troubleshooting by elimination...

    One thing i would appreciate is a clear list of things the tech should check as I will be there with him when he comes next...


    I thank you all for all the help you are giving me...
    I should have gone with my first instinct and install the system myself.
     

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