New Ductwork or not?


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Old 09-24-06, 08:42 PM
L
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New Ductwork or not?

New poster so please be gentle and sorry for some of the unprofessional descriptions in my post...I'm somewhat new to the whole home fixin's

Background: Live in Tampa, FL area, with an average temperature of freakin' hot for most of the year
My wife and I previously had a ~20-25 year old 2.5 Ton condenser and air handler. It kept going out about twice a year so we decided to bite the bullet and purchase a new unit. As it was uncomfortably hot in the 3 rooms farthest from the air handler (which made sense as the air had to travel much farther to get to those rooms) and we wanted to send air to the Florida room (so we could get more use out of it), we decided to get a larger unit. We ended up getting a 3.5 Ton condenser and air handler. Our living space was ~1600 SF originally, and with the florida room it was ~2000 SF. The contractor had also suggested that we upgrade the ductwork, but the a/c units were a large chunk of money so we decided to opt for just upgrading those then doing the ductwork later.

The rooms farthest from the air handler still seem warm so we decided to get the guy back out to give us an estimate on the ductwork. He said that we needed to upgrade our old ductwork from insulated metal to the newer ductwork (that insulated flex pipe stuff). He also stated that the ducts we currently have were used for heating not really for cooling (which *could* make sense as the older couple that owned our house before us may have been old school Floridians that just used the ceiling fans to keep them somewhat cool rather than the a/c units).

We've noticed quite a bit of sweating around the plenum coming from the air handler which we have been told is also related to the old, incorrectly sized ductwork

OK, finally to the question:
Do we really need to get larger ductwork now that we have a larger air handler and condenser or are they just trying to get us for even more money? Do we just need to add mastic around the opening to give it some extra support when sealing the ductwork or will that just eventually break loose because the air handler is too large or the ductwork.

I appreciate any help with my decision.
 
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Old 09-25-06, 08:49 PM
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To take and go from 2.5 ton AC to a 3.5 on the same duct work is for sure a NO NO. Also did they run a AC load on the home first so you have the right size AC for the home. As Im not sure what you have in the home there its hard to say what size should be in the home. Mine down there was 1900sq ft and had a 3 ton worked just fine.
So yes you need new duct work for sure. First the AC cant do its job. Cause it could drop the temp in the home .But not run long enough to get the humidity out of the home . Down in Fl you want the humidity out for sure. Thats why the sweating around the plenum its cold but cant get the humidity out. He is telling you right.That old 2.5 AC should work at 1000 CFM and the new 3.5 at a 1400 CFM. He did put in a bigger blower I hope. So see you need bigger duct also more outlets off it.. That round flex pipe for duct is ok . BUT make sure they use the silver kind not the black flex pipe in the attic. If you dont put bigger duct in now . You will just pay more $$$$ to FPL for power When you run that AC.
Think I answered all If not post back right here same post.

ED
 
 

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