Adding registers/ducts to bedroom closets

[txjeff]

I have a 3 year new house in Granbury, TX. It is mostly brick faced. I have two walk in closets that are on outside walls. 4 months out of the year they get hot or cold since there is a lack of AC/heat registers in the closets (probably typical). I store things in the closet that are sensitive to temp and would like to keep the closets close to room temp without cutting holes in the doors and putting screens in (my first thought). I have a Goodman heat pump and central AC system. The ducting is various arms of insulation covered tubes (laymen term). Each bedroom has a duct/register (12 x 11 bedrooms). The closets are 8' x 4'. So I thought I could tap off of each duct arm in each bedroom with say a 4" duct (or so) and a small register in each ceiling of each closet. Is this an ok tactic? How hard is it to tap into an existing duct? Thanks.

[txjeff]

My neighbor (mech engr) had a pretty good idea. Disconnect duct from each bedroom register; put a T on the duct; add a new section of duct to each T to the bedroom register; then run like a 4" duct from the T to the closet register. Sounds pretty easy to me. Agree?

[kenney t]

just install 4'' runs of main trunk and it will be fine

[txjeff]

Thanks!

[energy_rater_La]

If you system can handle adding more ducts to the plenum,
you should also look at how the new ducts will return the air
to the r/a.
an undercut door will return (roughly) one supply grill
if you add more..how does air return from these areas?

adding ducts is more than just cutting holes in the plenum
and installing flex duct. if you cut a hole it should be mastic
sealed. also the location of the new duct on the plenum is
another issue..not off end cap..not too close to ahu or coil.
supply box to supply grill at sheetrock is another
source of duct leakage.

look carefully before you make any major changes. ask
your hvac company's advice. you may need more help than
you realize.

best of luck

[txjeff]

Well, thanks. I think you're right with that. Definitely the doors are only about a 1/4" off the carpet. I was thinking of putting an exhaust vent near the floor or the back of each closet. I plan to have a pro come out next week and look over the whole thing and see how much it would cost for them to do it. For now, I took my sensitive guitar out of that closet and moved it to the central closet. That's an easy fix.