High pressure enfinity

Discussion in 'Maintenance and Troubleshooting' started by rothy3652, Nov 14, 2010.

  1. rothy3652

    rothy3652 New Member

    I am hoping that someone out there can share or relate to the high pressure lockout problem I have. The unit is a 4 ton McQuay enfintiy water to air horizontal loop system. In heating mode i get high pressure lockouts at night. The pump runs well in cooling with no lockout issues whatsoever. Anyone out there have an input for me.-----here are some facts----410a refrigerant--52 degree in---44 degree out water temps--65 degree return--90 degree supply temp air temps
     
  2. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    check your air filter first.
    J
     
  3. rothy3652

    rothy3652 New Member

    high pressure

    air filter is new--no restriction on air flow---in fact with guages attached i have BLOCKED 80% of the coil to ramp the head pressure up over 425 and it still didn't trip---there has to b something else in the refrigeration ckt sticking or not opening---i don;t know much about this stuff----company says boards or bad connection on board giving false signals---??????
     
  4. teetech

    teetech Member Forum Leader

    That's good advice. High pressure lockouts in heating mode are often caused by insufficient air flow across the coil. It is best to take your air temperature readings at the unit.
     
  5. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    How old is the system?
     
  6. rothy3652

    rothy3652 New Member

    Unit was installed in April and had 0 issues whatsoever all summer long. It locked out again today---very frustrating- even more is the controls they put in them--i mean the boards--i just dropped a line to the place where i purchased the unit--trhe system is supposed to have a remote resest feature. It is the o terminal on the board. It is supposed to reset the furnace if you put power to it for 10 sec or more. I got that info right out of the manual. It works but only 1 out of every three attempts. I had the meter on the O terminal all three times i attempted to reset my high pressure lockout condition.---??????? Mcquay is tough to deal with to boot!!!! They give the same runaround each time we talk --board this false that----no results--
     
  7. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    How large is the return air and supply duct system?
    j
     
  8. teetech

    teetech Member Forum Leader

    The "O" terminal is commonly used to energize the reversing valve, not reset the unit.
    Frequent reset of a high pressure fault will cause more damage and shorten the life of your unit.
    I strongly suggest you find a qualified tech to fix the problem.
     
  9. rothy3652

    rothy3652 New Member

    The ductwork is 12x8 coming from one direction with one return register. The ductwork is 12x8 for one register coming from the other direction. It then picks up another register and the ductwork goes to 24x8. The two trunks meet the plenum and go down to the furnace. The plenum is 28x8---I hope that makes sense--i tried to explain the ductwork as it works toward the furnace. As far as the post about the O terminal--i got that info from the manufacturer.
     
  10. rothy3652

    rothy3652 New Member

    I do believe in getting a tech here--bad part is when i contacted one he kinda quizzed me on everything that i tried and the result. I don' k now where to go though so he will see something else that i have not. I did take the end caps off of my ductwork-- he (technician) said that would be something to try until he got here---anymore info is greatly appreciated---tee tech----ami contracting thank u in advance
     
  11. teetech

    teetech Member Forum Leader

    65 degree return--90 degree supply temp air temps.

    If taken at the unit your numbers are within specifications as long as the motor stays operational. It's also possible the high pressure switch is faulty but I am always cautious with high pressure faults.
     
  12. rothy3652

    rothy3652 New Member

    Why do say to be cautious with a high pressure fault---- are they a common occurence with these pumps or is it a result of this state of the art technology that takes years to perfect. It seems to me that these are all nuisance faults for two reasons-one is it always resets with one power cyle--two it happens at random times with different conditions with absolutely no pattern at all---weeks apart at times
     
  13. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Return air a tad small for a 4 ton.
    Not sure it's a smoking gun.
    How big are the openings?
    J
     
  14. rothy3652

    rothy3652 New Member

    I have three 12x16's on my first floor. My house is a 2100 ft2 ranch that is open. Ihave a 8x10 on my plenum. I have also taken one end cap off of the small trunk that only has one return register off of it as i descibed earlier. The end cap that i took off is 12x8. I have not tripped since i have taken the end cap off though it has only been three or four days. I have another Q while we are on the subject of ductwork and airflow. My unit can only put out what it can take in right. The board supposedly has a preset static pressure setting of .73 or something like that. Can i have too much return air without affecting the velocity or the volume of the supply? I hope that makes sense. I guess another way of saying it is if i am too small on the return side how will that affect the performance of the supply side as well as the static pressure setting on the machine? Does the s.p. setting only allow the blower to work so hard and how does it know what the s.p. actually is? I don't see any sensors in the unit although i never looked real hard.----thanks for the input
     
  15. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    "I have also taken one end cap off of the small trunk that only has one return register off of it as i descibed earlier. The end cap that i took off is 12x8. I have not tripped since i have taken the end cap off though it has only been three or four days."

    Interesting, we need to find out why that is if failure has indeded ceased. Need more detail of branches off that trunk and registers over openings.
    Joe
     
  16. rothy3652

    rothy3652 New Member

    Well ---- unit went off on high pressure lockout-----fortunately i was home to here it --here is some more facts----on the call for heat the compressor tried to start and after three seconds to five seconds the compressor shut back off---it never got into the cycle at all---thus i believe we can say that it is not air flow---i say that compressor could run for 30 seconds or so with no fan running at all and not build that much head pressure-- i resest the unit and it hasn't tripped since---what about the txv---????? I dont know
     
  17. rothy3652

    rothy3652 New Member

    well two ckt brds later the unit still trips intermittently at start up----this is the newest fact--i have been next to the unit on two occasions when the furnace has attempted to start---the contactor for the pumps and the compressor drops in and then back out within one second--there is no high pressure--that is a fact--the unit then indicates high pressure fault on the main board----i have taken the high pressure switch off the board and replaced it with a jumper---i have taken the high pressure swith and ran it through the signal for the contactor--it is in series with the 24 volt signal for the contactor---supplier recommended i do this in order to further prove to McQuay that it is a software issue on the board itself---anyone out there got a similar product that can relate
     
  18. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    I recently serviced a unit who's fault code indicated high pressure. Since the pressure switch and wiring harness "ohmed" out, I replaced the board. (new board had internal short to add to my fun) Once a properly functioning board was installed, unit failed to start- high pressure.
    Instead of testing the switch again, I plugged leads into new switch- heat pump worked fine.
    I tested old switch for resistance and also 24 volts on both sides and had good reads.
    It seems as though switch was intermitantly opening which tests may have revealed, but it would be easy to suspect the moment it opened that you failed to make good contact with test probe (particularly if it closed again right away).
    Once I replaced the switch, I got to change the circuit board back to the original (good times).
    Moral of the story, I will simply plug a pressure switch in before I replace another board for pressure faults.

    My question is- if it is a board issue, then how would jumping out the switch at the board solve the problem? Are there any other switches that you inadvertantly disabled/bypassed with your jumper?
    If your unit works the way you have it, do you need to fix it? You still have high pressure protection.
     
  19. rothy3652

    rothy3652 New Member

    AMI---the distributor asked me to install a jumper on the board where the pressure switch used to be. THe high pressure switch is still protecting the ref ckt but now if the board locks out high pressure(not a true high pressure but a nuisance trip) this is hard core proof for some genius engineers who made this board. The board has already locked high pressure with no switch connected to board. If the head pressure would be over 455 psi the contactor would drop out and the board would start it's delay time for short cycle protection and the unit itself would "lock out". To answer the Q about other switches that i could be bypassing i have to say no but that is not to say there isn't something in the programming. What brand did u work on that had board problems? Thank U
     
  20. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Ahhh....
    Your previous post did not indicate that failure continued with the jumper in place. Obviously, if it did, you need a board or you can stick with your current fix.

    To answer your question about brand; (first let me remind you the board wasn't the problem) it was a Climatemaster.

    joe
     

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