Our 30 yr old 2 story Ryan home only has a double return duct in the center of the house. There is a return duct/vent in the foyer and one in the second floor hallway. The foyer is open to the second floor.

Our master bedroom has cathedral ceilings and its usually several degrees warmer in the summer and colder in the winter. The other bedrooms are similar but not as bad as the master. Our first floor temperature is consistent with the thermostat.

I have access to the attic/crawlspace.

My idea is to add a return vent in each bedroom and connect them to the central return duct. At the least I want to add a return vent to the master. I was thinking of using the flexable insulated 6in round ductwork. I was going to partially block the return vent on the first floor to pull more air from the second floor.

Are there any issues that can arise? From what I see searching online I cannot hurt the system by adding to many returns.

This message has been edited. Last edited by: gpbst3,

definitely adding an additional return will make the system work a bit easier, and perhaps improve circulation a bit

Way far from being an expert, it would seem just adding a return would not increase the total air returned unless the main duct was larger, at least from the closest return to the unit.

For Example, I know, when we installed new larger AC, my AC guys had to make the return larger in my bedroom, which is closest to the outdoor unit. I am pretty sure the return duct itself was made larger from the return vent out to the unit.

I think Whup is probably right. We've got some HVAC experts that I expect will be along too.

If I've learned anything from a couple times they've chimed in its that the airflow and volume has to be designed as a system rather than an item here, item there with a hope it all works as desired together. This may fall in that category.

quote:

Originally posted by Georgeair:
I think Whup is probably right. We've got some HVAC experts that I expect will be along too.

That's who you're going to need to hear from.

I know it doesn't seem like it, but the design of the supply and return ducts in forced-air systems has a lot of science behind it. It's not as easy as just "adding more <whatever>."

I work in the HVAC field, but in a more commercial type setting.

When we use flex duct we try not to use more than 10 feet of it in a given run. With flex your air flow diminishes very rapidly the more you use it.

Your return air will always find the path of least resistance so if the returns are too long or too many turns it won't help as much.

I know in past houses I live in sometimes it could be an insulation issue with your master bedroom that causes the temperature difference.

Good luck with whatever you do. I hope it works out for you.

Not an HVAC pro here either, but if I were you I'd hire one to take static pressure measurements of both supply and return sides of your system and let the math tell them what to recommend to improve your system.

Where are the supply registers in the areas you want to add return ducting to? Depending on where they are you may need to close off the hallway returns.

quote:

Originally posted by SgtGold:
Where are the supply registers in the areas you want to add return ducting to? Depending on where they are you may need to close off the hallway returns.

They are pretty much on opposite walls from where I would put the returns

gpbst3, we had a cathedral ceiling design house at one point. Loved the space, but it had some annoying quirks in either really hot or really cold weather. (Pretty much what you described).

The only way I found to "tune" the temperatures was to experiment and set the ceiling fans (2) to preset speed and up/down settings based on the season. Then it worked great- but obviously this was extrinsic to the heating/AC home system.

I visited a really large lodge-type house on a lake once and they had secondary thermostats on the ceiling fans. That was the only thing that worked for them-
Both our house and the lodge were older houses-

I would think with a new build that the HVAC folks would do better design work-

quote:

Originally posted by gpbst3:

quote:

Originally posted by SgtGold:
Where are the supply registers in the areas you want to add return ducting to? Depending on where they are you may need to close off the hallway returns.

They are pretty much on opposite walls from where I would put the returns

Are the supply registers as far away from the room doors as possible? If you put a return register in each room you will short circuit the return flow to the hallway and create a dead air space.

When I took a one-year break from plumbing, I sold hvac systems. Six years of hell. We used this chart. The final six feet or so, the return drop to the air handler / furnace, 25% larger. Sometimes I'd just sell duct improvements. Hey, a sale is a sale.

There is a pressure drop from flex duct but I'm not sure what it is, exactly. Cooling wants 400 cfm per ton; heat moves more slowly.

I don't know what a Ryan home is, but...

Adding a return vent to the effected rooms will help. However, 6" isn't large enough to make much of a difference. 8, 10, 12 depending on the flow needed. And flex is more restrictive than round metal duct, so upsizing is a must.

The main duct to the equipment would also need to be upsized. Airflow is the key to ones comfort and efficiency.

If you have a print, I could tell you more, but not knowing or seeing what's in place, everything would be speculation.