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.
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.
Tell me you didn't tell them,which line was icing!
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.
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.
Last edited by tomntina; 07-08-2008 at 12:12 AM.
Reason: To add photo
Could be a restriction in the liquid line. I found one after a compressor failure. Copper dryer/strainer acting like a metering device.
Originally Posted by tomntina
What was I thinking???
I never do that again!!!