calleserra
08-05-2009, 01:04 PM
I need thoughts/ ideas on what might be happening. My A/C tech is clueless and I am, too. Please jump in and give me your honest opinion on how to approach this before we tear it down.
Problem: Supply air temp varies by as much as 20 degrees between rooms. For example, masters bedroom supply is at 49 deg F, while the family room is at 72 deg F. Duct lengths coming from the supply plenum to both rooms are the same length- about 12 feet. Masters bedroom is 8" big and the family room is 10". All are flexducts.
Another bedroom at the other end of the house is being supplied with a 35 feet long, 12-inch flexiduct with supply grill temp of 59 deg F.
All flexduct runs are up in the attic. In the example above, return air temp is around 76 deg F (one return grill for thw whole house, size is 14x30).
My system: American Standard 13-SEER 4-ton unit mounted horizontally up in the attic. It was brand new when installed January 2008. I have a 2000 square foot house with good insulation and double pane windows. I also have active attic fans.
How can supply ducts have that huge temperature gap between each other. I can understand if they are off a couple of degrees which perhaps may be due to duct length variation. But 20 degrees gap is too much to stomach specially the two ducts are the same length and exposed to the same attic ambient air temp. My understanding is supply plenum should have one common temperature being shared by all supply ducts. Any clues?
Problem: Supply air temp varies by as much as 20 degrees between rooms. For example, masters bedroom supply is at 49 deg F, while the family room is at 72 deg F. Duct lengths coming from the supply plenum to both rooms are the same length- about 12 feet. Masters bedroom is 8" big and the family room is 10". All are flexducts.
Another bedroom at the other end of the house is being supplied with a 35 feet long, 12-inch flexiduct with supply grill temp of 59 deg F.
All flexduct runs are up in the attic. In the example above, return air temp is around 76 deg F (one return grill for thw whole house, size is 14x30).
My system: American Standard 13-SEER 4-ton unit mounted horizontally up in the attic. It was brand new when installed January 2008. I have a 2000 square foot house with good insulation and double pane windows. I also have active attic fans.
How can supply ducts have that huge temperature gap between each other. I can understand if they are off a couple of degrees which perhaps may be due to duct length variation. But 20 degrees gap is too much to stomach specially the two ducts are the same length and exposed to the same attic ambient air temp. My understanding is supply plenum should have one common temperature being shared by all supply ducts. Any clues?