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  1. #27
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,967
    Evap Metering Device: PISTON
    ----------------------------
    It appears that some of the evaporator circuits are not getting an airflow "heatload" on them or, a very low airflow "heatload" on all circuits, thus the liquid returning to the compressor.

    I did not do much 'review analyzing,' I may be wrong!

  2. #28

    you are low

    Sir, to make it very simple.. You are low on freon.
    You can not run 45' line set with out below on freon.
    The conderser is only charged for 15' to 25' of line set.

    at 75 degrees thats plenty of heat to give good preasure readings. You do not have a restiction base on the readings
    you stated. You are low on freon. Low high side preasure is to low.

    Even with not enough air flow you high side preaser is to low. It should be at least 200 psi.

    You should hear liquid line at evaporator unstable staving for liquid.

    i know that you are using a piston and you charge by superheat. On the low side..

    if its hotter than 75 when you charge system then you high side will be even higher.

  3. #29
    Join Date
    Nov 2005
    Posts
    15
    kylons20, I agree with your analysis that I should be low having not added any freon with a 45' line set and that the high side and low side are too low.

    However, I do know that I am still too low on air flow by a minimum of 15%, though I don't know if this is enough to cause a problem.

    I do not hear any noise from the liquid line at the evap.

    The tricky part is that the suction line temp is 42 degrees at the evap and at the condenser. This would indicate a blockage of some sort in the evap after the piston, thus causing a flooding of the evap and liquid refrigerant heading back through the suction line to the condenser.

  4. #30
    Join Date
    Nov 2005
    Posts
    15
    Originally posted by udarrell
    Evap Metering Device: PISTON
    ----------------------------
    It appears that some of the evaporator circuits are not getting an airflow "heatload" on them or, a very low airflow "heatload" on all circuits, thus the liquid returning to the compressor.

    I did not do much 'review analyzing,' I may be wrong!
    Yes, this has been suggested. To the extent that there could be an install manual or some other paper in the inlet side of the evap coil. I popped up the evap last night and used a mirror and light to see if this was the case, but all looks good; no paper.

    This brings me back to believing that possibly one or more of the feeder tubes in the evap are not flowing and causing all the liquid to only use the remaining tubes, thus flooding them. If they can not evap that much liquid, there will still be liquid by the time it gets sent back on the suction line. This would explain the 42 degree suction line.

    Does anyone know if being 15% low on air flow could cause these symtoms?

  5. #31
    Join Date
    Nov 2005
    Posts
    15
    The reason I ask about if being 15% off is a big problem is because it will be quite a bit of work to rectify. You see, my house is only 1232 sqft now, but I am adding 500 sqft later. That is why I went with a 3.5 ton unit. I have added ducts to bring me up to 1055 CFM, however, adding more will be counter productive when I do the room addition.

    I am not trying to say that I will not change out the supply plentum to a 20" but I need to invent places to dump to in the house that will be eliminated later with the room addition.

    BTW, the 4 ton coil only comes with 16' x 18" outlet. Thats only 288 sqin's. A 20" round is 314 sqin. isn't there some redundancy there?

  6. #32
    Join Date
    Apr 2002
    Location
    Phoenix
    Posts
    107
    1055/1400 = .7536 You are 25% low on airflow. In order to work as designed, you need to add 345/1055 = .3270 or 33% more airflow.



  7. #33
    Join Date
    Oct 2004
    Posts
    3,400
    It seems I missed something.

    Maybe others here have, too.

    What does your contractor say is the problem?

  8. #34
    Join Date
    Nov 2005
    Posts
    15
    Originally posted by dkinz
    1055/1400 = .7536 You are 25% low on airflow. In order to work as designed, you need to add 345/1055 = .3270 or 33% more airflow.


    Based on 400 CFM per ton, yes 25% low.
    Based on 385 CFM per ton, 22% low.
    I don't know where I came up with 15%, brain fade I guess.
    Is 25% enough to cause these symtoms?

  9. #35
    Join Date
    Nov 2005
    Posts
    15
    Originally posted by bwal2
    It seems I missed something.

    Maybe others here have, too.

    What does your contractor say is the problem?
    I assume you mean the contractor for the room addition as apposed to the contractor who installed the A/C, which was me. And I am by no means a contractor.

    If you meant the first, he was only going to do the framing and I was going to do the rest. So to my knowledge, he knows nothing of my A/C aspirations.

    I understand 3.5 tons is too big for my existing 1232 sf home, but should be fine after the 500 sf room addition. As a result the existing duct work is 25% inadequate.(I earlier stated 15% inadequate. This was a result of one too many beers.)

    Do you think 25% short of air flow is enough to cause these symptoms?

  10. #36
    Join Date
    Feb 2004
    Location
    michigan
    Posts
    677

    Talking

    Hey Mr Billpro you don't need a stethiscope. I take a screwdriver put it on what I want to listen to and then put my jaw bone next to my ear on the screwdriver. Works just like a stethiscope only cheaper and I usually hane on in my back pocket. Except at home. Boy was the wife PISSED when I forgot about the screwdriver and tore the couch one night. Man did that cost me. New couch, new love seat, new chairs, tables, lamps, everything. I'm still working to pay that mistake off.

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