Returns

18 years ago

Had a new furnace and a/c with upsized return drop installed and everything was nice. While the unit has plenty of capacity (sensible and latent), it didn't seem to be doing a great job at dehumidifying.

Since my basement is rather high in humidity, I did a comprehensive inspection of my return ducts and found some considerable leaks.

After plugging the leaks, the house seems drier, but as a 'bonus', the basement humidity has risen (not unexpected and will deal with that). But, the return static apparently has risen since the return drop is starting to 'oil-can' (had gotten rid of that from original configuration.

While the noise is not excessive, I am concerned about the welfare of my new VS blower. Looking at the ductwork to assess where an additional return could be installed, the most logical (easiest) would be in the laundry room. I know, probably isn't allowed by code or convention.

If it's a question of desireability, I could accept a little bit of heat or humidity from the washer or drier, once or twice a week.

Comments, please.

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Comments (5)

zl700
18 years ago
What setting do you have the blower at?

I would first try setting the blower speed slower, in the 350 CFM per ton, if not done already.
veesubotee
Original Author
18 years ago
The unit was set up originally at 400 CFM/ton. In an effort to improve dehumidification, CFM was lowered to 360 CFM. System did not exerience oil-canning in 1st or 2nd stage before plugging leaks.

You wouldn't believe some of the leaks I found. One, was a gap (I'm estimating 1/2" or more) which ran across a 22" trunk (was supposed to be connected).

After closing them up the OC started.

V
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udarrell_2007
18 years ago
I would get a dehumidifier for the basement.

Perhaps it needs another Return duct.

Also if possible, I would have large area filter racks installed at the Return entry area of each Return duct run.
- udarrell

Here is a link that might be useful: Correct Sizing of Residential Ductwork Systems
zl700
18 years ago
If the basement is finished and used on a regular basis and in fact may even have registers, than a sealed duct is usually a moot point.

Too many times I see people get all wrapped up in sealing their duct connections and then cut registers into them.

If in unconditioned, unused, crawl spaces or attics, seal them up tight!
veesubotee
Original Author
18 years ago
Darrell: Additional grills (low) were added to the 2 first floor returns with a net increase in grill size, and the upstairs return grill was enlarged.

The system included an Aprilaire 2200 MF along with a much larger return drop so I think the face velocity is good.

I have been dickering about putting a dehumidifier in the basement. Am concerned about sizing (33 x 33 x 10') and cost of operation. Have been looking at a 65 pt/day unit. Still looking to seal any/all leaks.

Z: The basement is used for storage and my workbench (which lately, I don't seem to spend much time at). The only 'conditioning' is from the uninsulated ductwork.

V