Replacing flex duct under belly - DIY?

Post all other heating and cooling questions here.

Moderators: Greg, Mark

Posts: 175
Joined: Tue Feb 26, 2008 8:33 am
Location: Anna, Tx

Sun Sep 01, 2013 1:05 pm

A few years back, I replaced the flex duct under the belly - and all has been fine. The blower motor went out on the HVAC unit and the repairman told me it had failed - and will continue to fail - due to excessive static pressure. His bill is $300 - and the motor is under warranty. Diagnose and replace took a total of 1.5 hours. OUCH!

I was under the house a couple days back and noticed it was way too cool to just be in the shade! I also noticed that every place there is a tie wrap supporting the ducting - that there is an associated 'squeezing' of the duct. I'm sure I could come up with some type of end-to-end "tray" for the ducting to rest in - - - but I am more of the mind to replace the whole she-bang with solid ducting.

Seems it would just be a 90° elbow off the main unit, straight along to a point that is in line with the two main vent holes (about 20 feet). "T" it there...and then elbow up to each of the main vent holes.

Is this something a DIYer can tackle? I'm not a sheet metal guy - so is this solid ducting available in sections? Is this a strategy even worth pursuing?

I should mention that with the current "Y" configuration under the blower - one side of the Y blows nice hot air in winter. The other side blows same volume but at half the temp. I know it is related to the positioning of the electric coils - but not much way to move them.
Opportunity has a shelf life.

Posts: 10
Joined: Sat Jul 24, 2010 3:37 pm

Fri Sep 06, 2013 2:06 pm

Yes, replacing the duct is fairly simple, but be sure you run it by an ac man to be sure your idea will work. You can buy pipe in 5' sections at any ac supply house in your town. Know what diameter pipe you need...this isn't a guessing is good enough thing. That affects the pressures.