Results 1 to 9 of 9
  1. #1

    Tech said unit is fine, so now what? It's hot!

    Okay, I'm having some issues with my A/C keeping up with the heat. It got pretty hot in here on a 100 day (82ish), but I know that is probably to be expected. The issue is that the A/C is just running and running and takes a very long time to cool. My home is ~2700 sqft and the thermostat is at the bottom of a 2 story great room. Not sure how to know how many tons my A/C unit is, but it says it had 6.63lb of R-22 charged at the factory. From the model it looks like it is 48k btu's. The unit is was installed in either 1996 or 2001 I believe.

    I had a tech out today and he checked the refrigerant and everything looked fine he said. I had manually checked the drop across the coil by measuring before the air filter and at the top of the plenum where the a-coil is housed (I have a gas forced air furnace with a-coil in the basement). The drop was between 11 and 13 degrees depending on when I checked it. 13 was after I used coil cleaner on the outside condenser unit. the a-coil was clean as well.

    So the tech basically said it was doing all it could and nothing was wrong with it. Would you expect more than a 13 degree drop? Also I went out to the condenser outside and while it was running the air coming out of the top almost seemed cool. I'm used to that air being very hot as it pulls the heat out of the refrigerant and over the coils. Not sure if that has anything to do with it, but just an observation.

    Other than an energy audit is there anything I could/should do at this point?

    thanks!

  2. #2
    Join Date
    Jan 2011
    Location
    Metro Atlanta
    Posts
    790
    take a picture of the service tag on the condenser and post it, or post the modle and serial number. That will help us tell you what size it is.
    The opinions expressed by me are not that of my employer.


    insulation modern marvels
    http://www.youtube.com/watch?v=g37riSkyZzM

  3. #3
    Join Date
    Mar 2012
    Location
    My house is in Texas..
    Posts
    141
    Seems to me that I is undercharged .. It's hard to say... Need more info.

    "Duct tape is like the force. It has a light side, a dark side, and it holds the world together."

  4. #4
    Join Date
    Jan 2012
    Location
    WEST COLUMBIA S.C.
    Posts
    293
    Need subcooling, superheat and type of metering device

  5. #5
    Here is a pic of the service tag, I believe it is a Bryant:



    AddMore22, what other info do you need?

    thanks!
    Brad

  6. #6
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,062
    Quote Originally Posted by utbigrod View Post
    Here is a pic of the service tag, I believe it is a Bryant:



    AddMore22, what other info do you need?

    thanks!
    Brad
    It is a 4 ton unit. Did the service ticket have any information on it as fare as temperatures, pressures, airflow in cfm?

  7. #7
    Join Date
    May 2012
    Location
    San Diego, CA
    Posts
    352
    Quote Originally Posted by utbigrod View Post
    Okay, I'm having some issues with my A/C keeping up with the heat. It got pretty hot in here on a 100 day (82ish), but I know that is probably to be expected. The issue is that the A/C is just running and running and takes a very long time to cool. My home is ~2700 sqft and the thermostat is at the bottom of a 2 story great room. Not sure how to know how many tons my A/C unit is, but it says it had 6.63lb of R-22 charged at the factory. From the model it looks like it is 48k btu's. The unit is was installed in either 1996 or 2001 I believe.

    I had a tech out today and he checked the refrigerant and everything looked fine he said. I had manually checked the drop across the coil by measuring before the air filter and at the top of the plenum where the a-coil is housed (I have a gas forced air furnace with a-coil in the basement). The drop was between 11 and 13 degrees depending on when I checked it. 13 was after I used coil cleaner on the outside condenser unit. the a-coil was clean as well.

    So the tech basically said it was doing all it could and nothing was wrong with it. Would you expect more than a 13 degree drop? Also I went out to the condenser outside and while it was running the air coming out of the top almost seemed cool. I'm used to that air being very hot as it pulls the heat out of the refrigerant and over the coils. Not sure if that has anything to do with it, but just an observation.

    Other than an energy audit is there anything I could/should do at this point?

    thanks!
    From a design point of view, is the 100 F summer temp normal in your city? I know we are getting heat waves across the country and the a/c units might not be designed for the high temperatures. Check your airflow and temperature through your registers. If your unit is working perfectly, it could be your duct work.

    Your observation is correct, the outdoor condensing unit should be expelling hot air (air temp is higher than the outdoor temperature). When the outdoors temperature is really hot, the unit had to work harder to make the refrigerant hotter so heat transfer can occur.
    You can call me Sam

    It should be a crime to be a mechanical engineer in San Diego
    Summer Design Temperature: 83 F Dry Bulb ~ 69 F Wet Bulb (California Climate Zone 7)

  8. #8
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,031
    Quote Originally Posted by utbigrod View Post
    Okay, I'm having some issues with my A/C keeping up with the heat. It got pretty hot in here on a 100 day (82ish), but I know that is probably to be expected.

    ...My home is ~2700 sqft and the thermostat is at the bottom of a 2 story great room...The unit was installed in either 1996 or 2001.

    I had a tech out today and he checked the refrigerant and everything looked fine. I had manually checked the drop across the coil by measuring before the air filter and at the top of the plenum where the a-coil is housed (I have a gas forced air furnace with a-coil in the basement). The drop was between 11 and 13 degrees depending on when I checked it. 13 was after I used coil cleaner on the outside condenser unit. the a-coil was clean as well.Would you expect more than a 13 degree drop?

    Also I went out to the condenser outside and while it was running the air coming out of the top almost seemed cool. I'm used to that air being very hot as it pulls the heat out of the refrigerant and over the coils. Not sure if that has anything to do with it, but just an observation.

    Other than an energy audit is there anything I could/should do at this point? thanks!
    You need to check the temp of the condenser discharge air & also the temp of the outdoor air near the condenser so we can establish the temp-split.
    According to your comment (air feels cool off condenser)it sounds like there is not enough heatload on the indoor coil or there is a problem in the refrigerant system...

    For some accuracy in both indoor & outdoor temp-splits you'll need to get a humidity gauge (available at most hardware stores) to get the indoor %relative humidity.

    At 95F outdoors & 80F indoors & 50% RH; the indoor temp-split between SA & RA should be around 20 or 21F, not 13F, but we don't know what the INDOOR humidity was, that affects the temp-split.
    Last edited by udarrell; 07-11-2012 at 06:48 PM. Reason: Clarifying some points...

  9. #9
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,874
    Call the same company back tell them its not cooling and you would like it checked again

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