Return to the Heating & Air Conditioning Forum | Post a Follow-Up

o
Advice on Badly Undersize Returns

clip this post email this post what is this?
see most clipped and recent clippings
Posted by mudgod (My Page) on
Thu, Nov 22, 12 at 17:38

First off are there any good books that I can read on HVAC
I needed advice regarding my HVAC. I bought a house over a year ago and have been slowly figuring things out.
I have 2 HVAC units , 1x 2.5 ton for the top floor (4 bedrooms), 1x 5 ton for the main floor/basements which both have badly undersized returns from what I've read. I'm going to separate it into separate messages to make it easier to decipher

Follow-Up Postings:

o
RE: Advice on Badly Undersize Returns

clip this post email this post what is this?
see most clipped and recent clippings

Upstairs
2.5 Ton for the top floor (4 bedrooms), two returns (16x16 actual grill not opening) w/8inch and 10inch flex duct). The filter is 18x20. From what I've read I should have a 20x25 filter.
What I was thinking ideally was to run
3x8" returns from 3 bedrooms
1x10" return from 1 bedroom (master)
1x10" return (Hall / original)

How do I figure out the max size return plenum to buy (that would fit my unit)? Also when connecting to the plenum can I connect on any side or only on vertical surfaces (sides)

Alternatively if I merge the 3x8" and 1x10" into a junction box and run a 14" to the existing plenum how bad of an idea is that? Will still be undersized on the return

o
RE: Advice on Badly Undersize Returns

clip this post email this post what is this?
see most clipped and recent clippings

Downstairs
5 ton for the basement and main floor. It also has a 18x20 filter and ONE 22x22 grill (actual grill not opening). The return grill is near the stairs going to the basement with the main floor having an open floor plan. There are no returns in the basement (the plenum right before it hits the filter has a cutout and grill installed)

The plenum is half running behind drywall and connecting with a metal duct going to the upstair grill and would be somewhat of a bear to get to.

I was thinking of cutting a hole in the ductwork after the plenum and installing two returns to the basement area.
Regarding the plenum itself I can have someone try to remove and replace it with a larger one to accomodate a 20x25 filter but the problem is that would still be 50% undersized. From what I've read there should be two separate plenums coming out on either side w/a 20x25 filter on each. the other side of the HVAC is where the boiler sits. Also there isn't enough headroom to significantly raise the unit.
Googling I could find filters upto 24x36 on homedepot. Is it possible to connect a plenum of that size? Have the upstairs duct hook to it and the basements new ductwork as well

Here is a link that might be useful: Downstairs 5 ton system

o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Heating & Air Conditioning Forum

Instructions

  • You must be a registered member and logged in to post messages on our forums.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review the contents and make changes.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • It is illegal to post copyrighted material without the owner's consent.
  • HTML codes are allowed in the message field only.
  • No advertising is allowed in any of the forums.
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.



 
Click here to learn more about in-text links on this page.