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Thread: THPRE

  1. #40
    Join Date
    Jan 2013
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    TRAIL,OREGON
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    68
    Got that. I was just not thinking for a min. I had out conference with Goodman rep. by telephone friday. She wanted static pressures and has not replied since being given the numbers. static pressure numbers are ; return air w/outside vent on = .04 max. measured , supply side air .25 to .27 giving a total of .31 to .30. My understanding is that this puts air flow out as a source of my problem. During our test the unit took about ten min. to build up to 610psi then started cycling from 400 to 610 with the cycles becoming progressively shorter finally working down to less than 60 seconds for complete cycle. The other thing to keep in mind is that this unit has never worked even once in transition from hot to cool or back again!

  2. #41
    Join Date
    Feb 2009
    Location
    Tallahassee, FL
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    6,007
    Your return reading is inaccurate. Cant be that low. And how is that outdoor air filtered?

  3. #42
    Join Date
    Jan 2013
    Location
    TRAIL,OREGON
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    68
    The outside vent is a 6 inch. with a motor to open and close. As far as I know it has just a screen and a rain hat. I watched the tests and they were done with the indoor filter removed and the louver door loose but mostly closed. We ran all tests three times. I ofcourse do not know how accurate his equiptment is but they are certainly a reputable firm - and not the one who installed the system. One other fact is that when we were on the phone yesterday we disconnected a 16in. duct right at the plunum. The pressures and cycle rate did not change. So this was with no filter,the vent open,and the filter door open and the door to the room open. As well as having the duct off ot the plenum - If this is not enough air flow there would have to be something right in the air handler?

  4. #43
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    67,712
    The static neds to be aken with the air filer in. And the louvered door closed And the door is part of the PD drop the blower works against.
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  5. #44
    Join Date
    Jan 2013
    Location
    TRAIL,OREGON
    Posts
    68
    Ok but if the system was wide open in the return and had a 16in. duct removed from the plenum and I was still watching 610psi to 400psi in under 1 minute cycles there must be a further prob;lem? I mean that with sstatic pressure minimal and cfm close to 2100 there should not be an air flow problem causing the 610 high side?

  6. #45
    Join Date
    Dec 2010
    Location
    WV
    Posts
    115
    goodman has factory reps...sound like u need one, you need some real answers

  7. #46
    Join Date
    Jul 2009
    Location
    South Carolina
    Posts
    3,068
    If you have an airflow problem the 3/8" line should get very hot at 600 psi for any length of time. It sounds a lot like an overcharge condition or a liquid line restriction. Almost every Goodman 410A unit I've installed has been overcharged from the factory. I put in a 15 SEER 4 ton Goodman a few months ago with an 80 ft. line set & didn't add an ounce of gas but the charge was perfect. It should have needed about 2.5 lbs extra refrigerant to compensate for the line set so the unit was about 15% over charged from the factory. Also your indoor coil sounds like a match but if its too small that would also cause the problem you describe.
    Gary
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  8. #47
    Join Date
    Oct 2005
    Location
    Pacific Northwest
    Posts
    2,266
    THPRE: are you in Oregon?

    The last 4 ton goodman r410 system that installed called for a 7/8 suction line.

    A partially restricted (kinked) suction line will cause high head pressures and fluctuations.

    The static pressure tests is only effective if the blower is functioning correctly.

    How and where are static readings taking place when there is likely no supply and return plenum?

    The check me test is very tricky in a manufactured home unless a plenum was installed under the furnace and there is at least a 12" return air plenum.

    I'd hazard a guess that the air handler has little or no supply plenum and it's installed to the rear of the mechanical closet. If so you'd hear a noisy cavitating sound. Likely the outlet of the air handler is pointed directly at the floor.

    If your static pressure readings are taken beyond that point then they are not accurate.

    The "check me" test is only relevant if the input numbers are accurate.

  9. #48
    Join Date
    Jan 2013
    Location
    TRAIL,OREGON
    Posts
    68
    Only phone conferences are available here. Very frustrating. We have sent pictures and now the static pressure reading to the consultant. I hope for some answers on monday.

  10. #49
    Join Date
    Jan 2013
    Location
    TRAIL,OREGON
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    68
    The suction line is 7/8 and the liquid line is 3/8. I was guessing before. We have a tight fitting cabinet that houses the airhandler with the filter opening on one side and the fresh air vent on top and yes the out let is pointed right at the floor and directly into the plenum which is judged by all the techs that have seen it as "adequate" -- not great . Never hear any cavitation type noises. The outlet plenum is at least 24in. deep but I don't know the other dimensions. The static air on the supply side was taken through a hole drilled in the airhandler cabinet just above the floor. So it is above the also above the plenum. Thanks,THPRE

  11. #50
    Join Date
    Oct 2005
    Location
    Pacific Northwest
    Posts
    2,266
    Quote Originally Posted by THPRE View Post
    The suction line is 7/8 and the liquid line is 3/8. I was guessing before. We have a tight fitting cabinet that houses the airhandler with the filter opening on one side and the fresh air vent on top and yes the out let is pointed right at the floor and directly into the plenum which is judged by all the techs that have seen it as "adequate" -- not great . Never hear any cavitation type noises. The outlet plenum is at least 24in. deep but I don't know the other dimensions. The static air on the supply side was taken through a hole drilled in the airhandler cabinet just above the floor. So it is above the also above the plenum. Thanks,THPRE
    Well there you go. The discharge static pressure reading cannot be made through a hole in the air handler and it sounds as though the air handler is sitting right on the floor of the mechanical room. This is no good. Please post pics.

  12. #51
    Join Date
    Oct 2005
    Location
    Pacific Northwest
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    2,266
    Also; this is why your return and supply static readings are the same.. Essentially you are reading the same negative pressure in two different locations. This is also why removing the supply duct from the plenum made no difference.

  13. #52
    Join Date
    Jan 2013
    Location
    TRAIL,OREGON
    Posts
    68

    thpre

    The system has been evacuated and recharged numerous times while replacing the tx-valves and the drier. Also it passed the check me as to temp and pressures. I would think the charge would be correct by now. Yes the liquid line was considerably hotter than the suction line during our tests but I do not remember the actual temps. Could a restriction in a line [or a puddle,as Goodman sugested] cause problems in heat mode and not in cooling mode? And then if they adjust the charge for winter and it works,how would we explain the lack of cooling in the summer until more refergerant is added?

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