Hi all,

Just bought a 1200 sq ft 1962 Rambler south of Seattle, WA a month ago. Kicked on the brand new 92% Payne forced air furnace last week and was surprised by how loud the sole return air register is. The furnace is located in a bedroom closet (down-flow position), as there is only a crawl space. The return air register is in the hallway right outside the furnace (this is not a central location of the house) near the ceiling.

I had an HVAC mechanic stop by to check it out, figuring I will need to add more returns, but he just advised moving the return to the central living room/kitchen area (above the hallway entrance in photo 3) with flexible duct through the attic space. Seemed like a good suggestion to reduce the noise. He indicated having only one return was normal.

Then I started researching airflow and circulation and have hit a bunch of contradictory info leaving me confused about the best course of action. Some sources say you should have cold air returns in every room for the most efficient heating, others seem to indicate having only one return is fine? Some say the returns should be near the floor (makes sense), others seem to install near the ceiling? Then there's undercutting the doors or adding grates to them so when they are closed at night you still get proper circulation?

Any thoughts would be greatly appreciated. I have replaced a few furnaces in my day and run duct work, but never had a great idea of the proper layouts for maximizing efficiency. Thanks!

 

I lived in a place with only one return like that and everything worked pretty well. That said, it was just my girlfriend and me so doors were rarely shut inside so I don't know if we would have had issues with doors being closed for extended periods.

You have vents in each room, right?

How is the temperature in the house in the different areas?

 

Yes, vents in each room. Haven't used it enough and it hasn't got cold enough to know for sure, but temps seem pretty consistent.

 

I'd live with it a little while and see how it works.

What is the noise - rattle of the duct, air turbulence, ...?

 

Air turbulence. Not something we're going to be able to live with, it's really loud and right next to our bedroom. Sounds like a plane is taking off inside the house.

 

You should have returns in any room, except bathrooms or kitchens, which can be closed off by means of a door. In my area it is required.

 

Thanks for the advice. Think I'll move the return as suggested and install something like this in the bedrooms: Tamarack TTi-RAPR12.4 Return Air Pathway RAP - Tamarack Ventilation System

 

I'd much rather see a real return system. You could put a return in the ceiling of each room & install flex back to the return plenum. Easy, inexpensive, & most importantly, will work WAY better.

 

Thanks Grady. Would they all need to have their own line to the plenum or can I join 2 with a T before the plenum?

 

You can join them as long as the duct going to the plenum is large enough to handle both returns. How big are the rooms?

 

1 @ 120 sq ft, 2 @ 90 sq ft. Would be joining the 120 and a 90.

 

The noise is most likely due to high velocity in the return air grille. Adding return air ducts as suggested by Grady IS a definite improvement. You might try simply removing the grille to see if it makes a significant difference in the noise level and then either replacing it with a grille with much less restriction or trying to straighten the louvers on the existing grille with pliers as a temporary stop-gap measure.

Newer furnaces have higher velocities in their airflow and that will often make a new furnace in an older ductwork system noisy. You MIGHT be able to slow down the blower but you would need to also measure the temperature differential across the heat exchanger so this might be a job for a QUALIFIED technician. Unfortunately, finding a competent technician may be difficult.

 

Sorry for the slow reply. I've been out of town for a few days.

For the 120 sq. ft. room I'd use a 7" return & a 6" for the 90 sq. ft. room. An 8" common would be a little small, so I'd suggest a 10" since 9" duct is hard to find.