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Plasbot 07-29-2013 02:43 PM

Return air nightmare
6 Attachment(s)
I had a lovely Trane XR15 installed with new blower installed a year and a half ago. There was a problem area, the backroom which was a flat-roof addition. They managed to get a supply line to it. They got it all done in one day. The guy said I probably needed some more returns for the system and that he would get back with me. Well what I didn't know was he had a liver problem of some sort and unfortunately passed away several months later. In that time I had contacted him but apparently he was a one-man company and it just fell apart without him, leaving me with the problem. He didn't pull a permit or get an inspection either.
I got the state of Texas to come out and inspect it, and they found a bunch of stuff wrong, but thats about it. At least I got an inspection. They told me my return air was terribly inadequate. But that's all they could do for me.
That backroom has been a problem ever since. Even though it is pretty open to the rest of the house, it just doesn't get much flow.
The inspector gave me a nice write up, heres some of it:
'..installed this system on a single 16X20 ceiling return air grille that is too small. .. grill will deliver 500 cubic feet, this system on a 10" flexible return air duct ... at manual D velocity of 700 feet per minute, this duct will deliver 300 cfm when 1200 cfm is required'

So my thought is that I need to install a new return duct or ducts, starting with the backroom. The problem is getting duct through to there. The only way (besides cutting a hole in the roof as the previous owner did), is to run it into the kitchen and through the wall where the addition meets the main house.
My plan is to run a return duct through the kitchen and up back to the a/c.
It would only allow me to upload 6 pics:
1-the return grille
2-the duct from main return to system
3-the supply duct that goes to backroom
4-same supply duct going through kitchen
5-same supply duct where it goes through closet
6-crude drawing of house
I will try to post the rest of the pictures after this

Plasbot 07-29-2013 02:54 PM

6 Attachment(s)
Here are some more pics.
1-supply vent in backroom
2-backroom/kitchen wall area
3-backroom closet and supply vent
4-in kitchen where i'm thinking to run duct
5-pic of backroom before remodeling
6-pic in kitchen of window before sheetrock went on and black window taken out, would have to run vent through one of those 3 squares.

beenthere 07-29-2013 05:11 PM

Your return duct, besides being too small, is also crushed. Probably can rerun it in 12" flex. Then when you add another return, it will only need to be about a 14" rounds.

The flex supply duct for that room that doesn't cool well. is also crushed some in the attic, and where it goes through the wall to gt to the register box. fix that, and you have better air flow.

Hard to ell from the pics. but that supply run looks like 6". Increasing it to 7 or 8" would also help.

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