HVAC Duct-work Issues and Code Questions......

Old 04-04-20, 12:57 PM
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HVAC Duct-work Issues and Code Questions......

Hello All,
I have requested some work to be performed to our duct-work under our Home Warranty contract and have some questions; as I am leery about the HVAC company tasked to perform the work. I live in Mobile, Al. and our home was built in 1994.

They repaired our AC two weeks ago (compressor capacitor) but they did not address the duct-work issues I had pointed out. In fact they didn't seem interested in working on the duct-work and even argued it probably wouldn't be covered anyhow.

My contract does cover duct work though and our Home Warranty provider has confirmed that. So the HVAC company is scheduled to come back out in 3 weeks. I would like to have your opinion on a few matters though prior to their coming back out.


These are my concerns and your expertise is appreciated. Please only respond if you are well versed in HVAC and Duct systems, thanks.

1) There is some air leakage in our duct work which is covered. The contract clearly states such and my Home Warranty company verified such.

2) The bonus room (above garage) does not get sufficient air as it is always 4 or 5 degrees warmer than the rest of the house. I understand bonus rooms are a challenge but I feel they erred in the original duct-work design.

The flex duct that supplies the bonus room is 35ft long which seems excessively long and it is 3 pieces spliced together. So it runs out of a 14in x 14in rigid box (as pictured) and 35ft over to the bonus room register. That flex line also supplies the bathroom, so there is a "y" in the flex about mid way that converts to a smaller flex to the bathroom.

So the plenum in the attic is about 5ft long. They come off of that with a 12in flex line that supplies this rigid box. The box is about 6 ft. away from the plenum.

The box then has 4 flex lines coming out of it with the one on the left running over and up to the bonus room. The HVAC company calls this a "spider" system. This seems like a poor design originally to me? It seems they should have run rigid duct-board off of the plenum over to where this box is and then made a 90 degree left turn and ran it another 10ft or so toward the bonus room. They could have then ran shorter lengths of flex duct off of that.

To me that seems like it would have been a better design. Otherwise, they should have incorporated some metal duct here as it is less restrictive? I am no HVAC expert though and I am not sure how this should now be addressed so your input is needed here.

3) Is there anything else that you feel needs addressing?

a. I do see there are some kinks in the flex that needs to be corrected.
b. There is some black flex that y's off of some of the silver flex. What type of flex is that and why did they not just come off of the plenum itself?
c. The flex that comes out of the top of the plenum appears to be two pieces spliced together also even though it is a short run. Should I bring this up?

Your input is greatly appreciated.

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