Going from an open return to a ducted return-- is this a huge pain? (video inside)
I've got an AS GAM5 system with an open return. As many of you have told me, one of the reasons why it's so noisy is because it's an open return and because the GAM5 is a positive pressure system with the blower on the bottom.
So what I'm wondering now is this: how much of a pain in the rear would it be to have a contractor turn my open return into a ducted return and put some grilles throughout the house.
Here's a video (you can ignore the commentary) of what my system looks/sounds like in operation:
As you can see, there are ducts already going to the lower floors so I'm thinking it might not be a huge deal to put some returns downstairs, though I'd ideally love to have a return in every bedroom upstairs with the whole "hot air rises" thing.
Well, that type of installation certainly is among the least sound attenuated installations possible...
One thing that may help a bit would be less restrictive air filters, the ones you are using a terrible.
ECM blowers, even the constant torque variety like the GAM5 has, make less noise at lower static pressures.
The blower speed may also be set higher than it needs to be.
Yes sadly that's how my earlier system was set up. I've learned that a majority of the builders here in South FL went for the cheapest and easiest installation of AC systems, hence the single return. The blower speed is at a 2 out of 5, but I'll try to get a less restrictive air filter for sure.
Do you think changing the setup, ie going from an open return to a ducted return, would be worth it? Could I expect better sound as well as more efficient cooling?
Slowing the blower to the recommended speed is a start...........I'll give more suggestions later.........the wife awoke.
What tonnage is the air conditioner?
Air flow may be set much higher than needed...
With a TXV refrigerant metering device, you could possibly use 340-CFM per/ton of cooling.
If you can make your home more efficient, you could eventually replace the A/C with a smaller tonnage unit requiring much less air flow.
You may have an oversized equipment system on an undersized duct system...
Follow the advice of the other PROs regarding grille sizing & type of filters used.
I enjoyed the revealing video; it is very noisy...
When the sq.in. area of grilles & filters is increased airflow velocity decreases which reduces airflow noise levels...
It sounds like the blower is contributing a lot of the noise.
This is a 4-ton American Standard GAM5 system. My house is 2300 sq feet, and my previous system was a 4-ton Trane 900 XE circa 1986 that was much quieter. My contractor warned me that the AS system would be louder because the blower was located below the coils rather than on top of them and with an open return, there wasn't much to muffle the sound.
I've been told that when the return is ducted on this unit, it actually tends to be very much on the quiet side. Is it possible to retrofit this with a ducted return or will that be cost prohibitive?
Originally Posted by udarrell
I would run a large metal duct from the Return Air chamber to the conditioned areas with two separate large Return air grilles with deep boxes so it gets the airflow through the filters down to at or near 300-fpm velocity.
Originally Posted by Lugh
I would also reduce the blower speed to 350-CFM per/ton of cooling or 1400-CFM.
That will run a colder coil & reduce the Btuh for longer runtimes & improved dehumidification.
Of course, U could seal the RA box grilles & NEVER use a filter at the furnace.
Additionally, you could sound insulate the RA box.