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  1. #1
    Join Date
    Jul 2008
    Location
    Dorval, Quebec, Canada
    Posts
    8

    Return duct size and frost on coil.

    Had a NEW electric furnace and heat pump installed a month ago. Installer suggested I should increase the size of my return air ducts. The house is a 1950’s bungalow, 1000 sq. ft. plus a basement.

    I removed the grates off the returns and measured the openings going to the ducts. There were only 3 return openings measuring a combined total of 108 sq. in.

    Everything worked fine until a couple of days ago. The A/C stopped cooling and when I looked the line going into the coil was covered in thick frost. Not the insulated line. The non-insulated one. I called the service people and they wanted to know if I had increased the return duct size. I had not. This they claim could be causing the problem.

    Worked all day Sat. installing another return grate and ducting to add another 52 sq. in. bringing the total to 160 sq. in. Still getting frost to the extent I have to shut the A/C off every few hours.

    The duct size going into the bottom of the furnace is 210 sq. in. Do I have to further increase my return ducts by another 50 sq. in to match this or am I completely off base. I am no HVAC pro by a long shot.

    To give the A/C additional return air I opened the cleaning port in the return duct and left the filter door off. Still getting frost.

    I think I have more than a return air problem. Any comments or suggestions welcome. Should I increase the return ducts some more or is it likely I have another problem. The service guy is coming back this week but I don’t think I can accept if he claims this is all due to duct sizing.

    Thanks in advance.

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,317
    If the little line was freezing, its not caused by your return being to small.
    You got another problem.

    Call them back, and remind them, the liquid line will not freeze because of an undersized return.
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    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  3. #3
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Tell me you didn't tell them,which line was icing!

  4. #4
    Join Date
    Mar 2001
    Location
    North Carolina
    Posts
    428
    small line frosting going into air handler sounds like partially clogged piston or bad expansion valve. probably a Goodman air handler piston is right at the door and would be more noticeable than an expansion valve as far as seeing it outside the cabinet.

  5. #5
    Join Date
    Jul 2008
    Location
    Dorval, Quebec, Canada
    Posts
    8

    Ice on line

    I'm trying to attach a photo of the ice to see if it helps identify the problem. Not sure if I did it right or not.
    Attached Images Attached Images  
    Last edited by tomntina; 07-08-2008 at 12:12 AM. Reason: To add photo

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,317
    It didn't work.
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    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  7. #7
    Join Date
    Jul 2008
    Location
    Dorval, Quebec, Canada
    Posts
    8
    I think I got the photo attached now.

  8. #8
    Join Date
    Mar 2001
    Location
    North Carolina
    Posts
    428
    Looks like you have a bad expansion valve there.

  9. #9
    Join Date
    Sep 2006
    Location
    erwin nc
    Posts
    86
    looks like trane ,did they take the piston out before installing txv ?

  10. #10
    Join Date
    Jul 2008
    Location
    Dorval, Quebec, Canada
    Posts
    8
    I'm not sure what they did during installation. I'm just trying to get myself some background info so that they don't try to snow me when they say they fixed it. When I ask what was wrong, I never seem to get a straight answer. The last guy here said something about a wrong part being installed and they had to get a new one. Hopefully they will get back with the part and finally get this thing going. I nice new box that sucks electricity and blows warm air in the summer is not what I spent 7 grand on.

  11. #11
    Join Date
    May 2007
    Location
    DC Metro Area (MD)
    Posts
    3,371
    Can you post the model numbers of the outdoor and indoor units? That might clarify things. Is that a new air handler? The new 4TEE air handlers should have a TXV factory-installed.

  12. #12
    Join Date
    Jul 2008
    Location
    Dorval, Quebec, Canada
    Posts
    8
    The air handler is a new TEE unit by the brochure. The actual model # TWE030C14080. The unit outside says XR14, the invoice lists it as a TWR4024 2 ton. Can't actually see the model # on the unit as right now it is dark and raining.

  13. #13
    Join Date
    Jul 2008
    Location
    Pittsburgh PA
    Posts
    37
    Quote Originally Posted by tomntina View Post
    Had a NEW electric furnace and heat pump installed a month ago. Installer suggested I should increase the size of my return air ducts. The house is a 1950’s bungalow, 1000 sq. ft. plus a basement.

    I removed the grates off the returns and measured the openings going to the ducts. There were only 3 return openings measuring a combined total of 108 sq. in.

    Everything worked fine until a couple of days ago. The A/C stopped cooling and when I looked the line going into the coil was covered in thick frost. Not the insulated line. The non-insulated one. I called the service people and they wanted to know if I had increased the return duct size. I had not. This they claim could be causing the problem.

    Worked all day Sat. installing another return grate and ducting to add another 52 sq. in. bringing the total to 160 sq. in. Still getting frost to the extent I have to shut the A/C off every few hours.

    The duct size going into the bottom of the furnace is 210 sq. in. Do I have to further increase my return ducts by another 50 sq. in to match this or am I completely off base. I am no HVAC pro by a long shot.

    To give the A/C additional return air I opened the cleaning port in the return duct and left the filter door off. Still getting frost.

    I think I have more than a return air problem. Any comments or suggestions welcome. Should I increase the return ducts some more or is it likely I have another problem. The service guy is coming back this week but I don’t think I can accept if he claims this is all due to duct sizing.

    Thanks in advance.
    Could be a restriction in the liquid line. I found one after a compressor failure. Copper dryer/strainer acting like a metering device.
    What was I thinking??? I never do that again!!!

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