Supply Air Vent?

**Rick Hurst** · 05-14-2007, 03:27 PM

Master bedroom 16X20 (9ft. ceilings)

2889 cu. ft. approx.

Only 1 supply air vent at ceiling is present.

Adjacent to this room is the master bathroom which has a master closet probably 12X5. NO supply air vent in this closet. Client says its a really hot spot.

Client is already living in the home and has for 3 years. (One of those lease to purchase deals)

She claims her bedroom is really warm in the summer more so than the rest of the home.

She does have a work desk in the corner of the room with a computer that is also up against the wall of the of this master closet which has no supply vent.

Do you think that this one supply air vent alone is capable of supply this room by itself and why do some HVAC contractors not put a vent in a large walk-in closet as such?

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Brian E Kelly · 05-14-2007, 04:01 PM

The size of the ceiling register will determine what the amount of air flow the room gets. My guess is that the computer was not figured into the A/C load design, but should not make that much of a difference. Most of the time when I designed a HVAC system I would consider putting in a run in the walkin closet depending on the size. But I would always consult with the owners as to what their intentions of the walkin closet were. Some clients lined the closet with cedar and then I would not put a run in the closet.
What is the size of the return air grill for the bedroom, that also has a lot to do with the comfort of the room. If the desk is blocking the return air grill that could be part of the problem.
Hope this helps.

**Rick Hurst** · 05-14-2007, 04:12 PM

The vent on the ceiling was the typical (1ft) width type vent. No restriction were observed in the attic space.

No return air vent was in the room, so I don't think the computer would be that detrimental since she only used it for a short time at night she stated. An hour or less.

At my own home, the master has (3) supply vents present but we also have (4) can light fixtures, a lighted fan. Being a prior model, they might have performed a heat load calculation which explains why.

**DavidR** · 05-14-2007, 05:57 PM

Depending on the BTU loss/gain requirements of the room one register might handle that size room depending on the size duct & size register feeding the room.

Personally I would not trust one outlet to properly cover this size room but there are a lot of unknown variables involved in determining if the proper size is installed.

From the statement made about it being too warm in the summer sounds like a lack of BTU's to me.

Closets are a little bit of a different animal, if there are interior walls surrounding the whole closet more than likely it will have no load on it so no register.

If it has any outside walls attached to it then some type of conditioning is needed.

**Rick Hurst** · 05-14-2007, 06:05 PM

Thanks David and Brian.

The end of the closet was adjacent to an outside wall as you mentioned.

**Jim Luttrall** · 05-14-2007, 06:55 PM

One thing to look at is the provision for return air.
Any room that has supply must have a return of some sort.
Unfortunately, it is all too common to see one central return and the under cut of the doors used at the return path.
Close the door and the return air path is restricted, especially if as in most master bedrooms, the bath return air path is through the bedroom.
If the door sucks closed when the unit is running, that is a sure sign there is not enough of a return air path.
Point is look at both sides of the air path rather than just the supply side.

**Thom Walker** · 05-14-2007, 07:26 PM

Not much good came out of the godawful "mold is gold" hysteria that was rampant here for several years. But a few things did happen with our HVAC installations. In homes built in the last few years, I more frequently find suspended flex ducts instead of stretched across the joists, far fewer hills and valleys in the ducts, returns for each bedroom, and when it's a walk in closet, it has a register. Return insulation is better and it seems like they are thinking more about where the return is located. It seems to me that the decade of the 80's has about 90* of the rturns low down on the only wall in the main living area that would logically fit a sofa.

From the builder's side, most are no longer carpeting the closets.

Tim Moreira · 05-14-2007, 09:17 PM

A bit off topic, but in all of the years I've worked in hospitals, it has never ceased to amaze me how the powers that be will decide without ever consulting anyone in the Facilities department about changing offices and rooms designed intent.

I have seen countless times where a small closet or storage room was taken over to make an office with say 5 people, 5 computers, 5 printers, 5..., you get the idea, all with a little 4-6 inch supply and return grill and then everyone wonders after they are moved in and everything is up and running, why it is so hot in here?

*Then* they call Facilities and *then* they ask what we could *do* to make it cooler!

Why don't they ever consult with the Facilities department prior to doing this is beyond me. This way we could calculate the heat gain for the new intended use of the room and make appropriate corrections. Not to mention the addition of the electrical and communications outlets they will need. Never happens though. Always after the fact.

Sorry, just wanted to vent a little cause it never changes.

**Thom Walker** · 05-14-2007, 10:33 PM

Tim,
Grow up! Just make it happen. If they wanted you to think, you'd wear a tie and have PhD or MD behind your name. Leave the thinking to those that are trained.

Just out of curiosity, how many times do you get calls after you've fixed there fuggups that it's too cold and drafty?

**Scott Patterson** · 05-15-2007, 06:47 AM

I would look at the return air. A large percent of the time when you find a room that is warmer or cooler it is due to a return problem. You can't put air in a room unless it has a way to get back out.

Richard Rushing · 05-15-2007, 07:27 AM

Originally Posted by Scott Patterson

I would look at the return air. A large percent of the time when you find a room that is warmer or cooler it is due to a return problem. You can't put air in a room unless it has a way to get back out.

Sure you can... open the door.

Seriously, if there is no return air... the door will slam shut when the unit kicks-on then pressurize the room. Not good.