Adding additional return vents.

[FLA Man]

Hello All,

I am thinking of looking into having a contractor install some additional HVAC return vents in some rooms that tend to run hot.

Right now the unit is only a single return, and in my opinion it seems to be too small, when the AC turns on it sucks the air filter right into the duct! It also sounds like a hurricane in the hallway where the return is located.

It is a Trane 3.5 ton unit, about 3 years old and my home is 1700sq ft.

Is this a smart thing to do? I am only asking because I want to make sure before I ask the contractor.

Thanks guys.

[D-Allen]

Personally I like to install return in every room (except kitchen & bathroom) It does a much better job circulating throughout the house. They must be sized properly and your contractor should be able to figure that out for you.

[udarrell]

Well, it'll probably need dampers on the Branch SUPPLY-AIR outlets.

Supplies & returns ought to be sized to meet the BTUH requirements of each room.

If the system needs more cycle runtime, you could use 350-cfm per/ton of cooling or 1225-cfm instead of 1400-cfm.

That would quite the noise level & the longer cycles might help balance the room to room temps; plus better humidity control.

Additionally, furnace Return Air Filter would better handle 1225-cfm verses 1400-cfm; Manual D 1225 / 300-fpm Velocity is 4-sq.ft (Ak) open-air-filter-area.

[FLA Man]

Would it be functional just to look into adding the additional return vents to the existing single return duct?

Or would adding them involve a complete overhaul of the return vent layout?

Thanks for the help, I have no clue when it comes to HVAC so I want to make sure that I have some basis before I ask the contractor anything.

Thanks,

[D-Allen]

If your contractor is worth a grain of salt, he will check the entire duct layout and discuss it with you

[George2]

Would it be functional just to look into adding the additional return vents to the existing single return duct?

Or would adding them involve a complete overhaul of the return vent layout?

Thanks for the help, I have no clue when it comes to HVAC so I want to make sure that I have some basis before I ask the contractor anything.

Thanks,

Right now it sounds like you have a filter grille. What size filter does it take?

If you add a return to ever room, you'll need to have the filter on the air handler. Yes, this gets involved (and costly).

A cheaper way (and it works as well if you never close the doors) is to add another filter grille.

It sounds like you're short on return now (very common over sight).

[FLA Man]

Right now it sounds like you have a filter grille. What size filter does it take?

If you add a return to ever room, you'll need to have the filter on the air handler. Yes, this gets involved (and costly).

A cheaper way (and it works as well if you never close the doors) is to add another filter grille.

It sounds like you're short on return now (very common over sight).

The return size is 14 x 20, which to me seems very small (Am I right?).

The Trane air handler has a filter in it as well, I already have to use it because I can not put a filter in the initial return (as it gets sucked into it).

[George2]

The return size is 14 x 20, which to me seems very small (Am I right?).

The Trane air handler has a filter in it as well, I already have to use it because I can not put a filter in the initial return (as it gets sucked into it).

You should only use one filter. At the unit would be the one. Yes, 14x20 is WAY too small.

The rule of thumb (to show you how off you are) is 2 cfm x sq. inches of the filter grille = total cfm.

You have (14x20) 280 sq in x 2 = 560 cfm. 1,400+ is needed, hence the noise...............