New heat and air unit installed.......a small problem...I need an answer...!!!!

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Forum topic by Rick Dennington posted 02-11-2010 04:59 AM 3086 views 0 times favorited 18 replies Add to Favorites Watch
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Rick Dennington

6377 posts in 3463 days

02-11-2010 04:59 AM

Greetings all, especially you heat and air guys: About 2 weeks ago I had a new h&a unit put in. They removed the air handler that was in the hall closet, and also the heat pump outside. They installed the air handler, new air cleaner, and some more duct work, and put it in the attic. They moved the heat pump from the North end of the house to the South end. This is all great, and the unit is soooo much quiter since gone from inside. Ok… here’s the problem. The guy put the air return in the hall (this ductwork is about 18” around), right between two bedrooms, and it’s sucking all the warm air out of the rooms into the return. It’s got a slotted metal grate to cover the hole. Ok….. this thing was “whistling” like crazy. I took it down, swapped ends, and cut that noise out. I even put a $.50 filter in, and it really whistles…....sucking the warm in.
My question is: Just short of calling them back out, is there a baffle I can make to reduce the air suction to keep the rooms warmer? I also had new insulation blown in (14”) after the unit was put in. Everything works great, the house is a lot warmer and QUITER, except the back bedrooms. How can I remedy this? I need to reduce the air return to a smaller diameter…. a wood baffle,perhaps with a smaller hole? You tell me, ok?......

-- " At my age, happy hour is a 2 hour nap".....!!

18 replies so far

View ajosephg's profile


1880 posts in 3829 days

#1 posted 02-11-2010 05:23 AM

I’m not a hvac guy but I’ll make a prediction. The noise is coming from turbulance of the air going through the grill and possibly the duct. Does the noise go away if you completely remove the grill? If so the solution is to find a grill that doesn’t cause so much turbulance. For sure you don’t want to make a baffle to reduce air flow (volume) as that would defeat the whole design of the system. Another possibility is to reduce the air velocity by using a larger return. (That only works if the duct is larger than the return grill). What does your installer say he’s going to do?

Good luck

-- Joe

View a1Jim's profile


117465 posts in 3846 days

#2 posted 02-11-2010 05:32 AM

Sounds like Joe has a good guess.

-- wood crafting & woodworking classes

View Dark_Lightning's profile


3381 posts in 3377 days

#3 posted 02-11-2010 06:04 AM

I’m not sure I understand the question:

1. The return whistles, but when you turned the grate over, it stopped, so that part is cured?
2. I hope there are supply ducts in the rooms. There is no reason to expect those rooms to get colder unless there is no warm air getting supplied during the “heater on” cycle…unless the inlets to the room don’t come from the heater.
3. Generally speaking, a LARGER return would reduce the whistling. I don’t make sense of what is being asked, but it’s late. (I get up at 3:30 AM PST to go to work).

Do not hesitate to call the contracter back if you have issues like this. They really don’t make sense. Note- the extra insulation is going to be a pain if they have to crawl in there to fix something.

-- Random Orbital Nailer

View TopamaxSurvivor's profile


18463 posts in 3944 days

#4 posted 02-11-2010 06:16 AM

I’d definitely call them back.

Sounds like you only have one return air inlet that is sucking a lot of air!! If you had 2 return vents, you could easily put in a balancing damper.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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John Gray

2370 posts in 4154 days

#5 posted 02-11-2010 06:56 AM

I agree with TopamaxSurvivor I’d definitely call them back.

-- Only the Shadow knows....................

View Rick  Dennington's profile

Rick Dennington

6377 posts in 3463 days

#6 posted 02-11-2010 06:57 AM

Hey Joe:... The noise is not really the problem. I just swapped the grille end for end and reduced the whistling noise going through the grill. The baffles( I guess that’s what you call them) were pointed the wrong way. I know this may not make much sence. But yes—- the noise goes away when I removed the grill. But so much air is going out the return duct, its’ taking warm air out of the bedrooms since it’s so close to them. I wasn’t sure about making a baffle, but you’re right….it would reduce the air flow, and I don’t want to do that.

Atom Jack:.. Yes, there are ducts in the rooms, and some warm air gets to them, but not like the rest of the house. I don’t need a larger return…. this one is about an 18” opening. That’s where all the warm air is going..
back to the air handler, recirculating it through the air cleaner, and back out again. This may be confusing, I know.

Topa: I think you’re right. My old unit had 2 air returns… one in the den, and one around the corner at the bottom of the air handler behind the door, which was loovered to go to the air handler. I think that kept the two in balance, and they NEVER whistled or made noise. I just think the return is in the wrong place. I’m gonna call them in the morning and see about it. It’s under warrenty, and I’m not satified with it at all. Thanks.

-- " At my age, happy hour is a 2 hour nap".....!!

View ajosephg's profile


1880 posts in 3829 days

#7 posted 02-11-2010 01:47 PM

Rick – I did miss the part about the cold bedrooms.

That’s one of the drawbacks of not having returns in each room. As you and others have said, the installer needs to make it right.

Unfortunately the majority of HVAC guys in this part of the country don’t spend the time (or don’t know how) to properly design a system. A good resource might be your local electric company. I know Carroll Electric will come out and do an energy audit which includes sizing the HVAC system. They also have a consultant named Doug Rye who is especially smart on these things. While he probably can’t make house calls, he for sure knows where to point you to get the answers you need – even if they aren’t what you want to hear.

-- Joe

View Sawkerf's profile


1730 posts in 3337 days

#8 posted 02-11-2010 04:59 PM

Rick -
Your system sounds like a pretty typical forced air system with a central return. Other than the noise, it sounds like it’s operating like it should. It may,however, need some adjustments.

Where are the heat registers in the bedrooms, and where is your thermostat? Can you adjust the flow thru the registers?

The system is going to cycle based on the temperature at the thermostat. If the furnace comes on when the bedrooms are comfortably warm, it may be necessary to partially close the registers in rooms closer to the furnace in order to increase the flow of warm air to registers further away. This will balance the flow of warm air throughout the house, and – hopefully – get the thermostat in sync with what you want for comfort.

As far as the noise issue, I would definitely call the HVAC folks back. Restricting flow at the return line probably isn’t the best solution, but they might be able to do something to cut the noise.

-- Adversity doesn't build reveals it.

View Rick  Dennington's profile

Rick Dennington

6377 posts in 3463 days

#9 posted 02-11-2010 05:19 PM

Sawkerf— Well… it’s not a forced air system. It’s a heat pump. I wish it was a forced air system, but we have no natural gas in the town I live in. So we have to use h.p. It’s a great unit…. a Trane ( I replaced the old Trane with the new one) It’s a 14 SEER h.p., and a 9.5 air handler. The heat registers in 2 b.r.s. are right in the middle of the ceiling, and the master b.r. has 2 registers. The thermostat is in the den. It’s the new digital kind.
Like I said, the air handler is in the attic over the garage, but I’ve noticed the registers in the den and kitchen are louder (especially the den..I have a vaulted ceiling w/ 4 registers), and you hardly hear any air coming out of the registers, or feel it in the bedrooms. I’m gonna try to close the ones in the den and kitchen a little and see if that helps…...... stand by for further information as we go along to correct this

-- " At my age, happy hour is a 2 hour nap".....!!

View MedicKen's profile


1615 posts in 3731 days

#10 posted 02-11-2010 05:21 PM

It sounds like the air return is under sized.

-- My job is to give my kids things to discuss with their

View Rick  Dennington's profile

Rick Dennington

6377 posts in 3463 days

#11 posted 02-11-2010 05:31 PM

MedicKen: I don’t think the return is undersized…. it’s about 18” in diameter, and drawing plenty of air through it…. too much air, I think. It’s got a 20” x 25” grill mounted to the ceiling below it. I put an air filter in it to see what it would do….. that sucker whistled like a west texas dirt storm….. took it out.. much quiter.
I would think the return is plenty big enough, but I’m no expert.

-- " At my age, happy hour is a 2 hour nap".....!!

View Mary Anne's profile

Mary Anne

1058 posts in 3477 days

#12 posted 02-11-2010 05:58 PM

Rick, I am guessing that the bedrooms are at the end of the line of ducts? Sounds like the bulk of your heat is going to another area of the house and your bedrooms aren’t getting enough. Unless your registers are right next to the return air, you should be able to balance out the system fairly easily with a little bit of trial and error to get things the way you like them. Make sure you have the registers wide open in the bedrooms and try closing down the registers in the warmer rooms a little bit so your warm air is getting distributed where you want it.

Oh, you mentioned putting in a $.50 filter. Try putting in a better quality one. It sounds like you have a much better (stronger) fan than before, and cheap filters will flex causing the whistling. You really should have a filter in there. And your louvers should be pointing down, btw.

View Rick  Dennington's profile

Rick Dennington

6377 posts in 3463 days

#13 posted 02-11-2010 06:15 PM

Greetings Mary Anne: You are right… the bedrooms are at the end of the duct lines, and deffinantly aren’t getting enough. Yea—- I’m gonna close the registers some to the other part of the house to see if that helps…it should. The loovers are pointing down since I swapped it end for end (he had them pointing up).
Oh… and the filter…. I was just using that for a test to check the whistling… it came right back out…. lol.
I have a good quality pleated filter in now, and helped a bunch. Now just to close some vents and see what happens. Thanks Mary Anne… by the way, welcome back….. where have you been… playing with that short-legged dog…...... lol lol.

-- " At my age, happy hour is a 2 hour nap".....!!

View Lifesaver2000's profile


556 posts in 3381 days

#14 posted 02-11-2010 06:36 PM

When I had my heat pump system installed, I had a problem similar to yours, with bedrooms at the far end of the house not getting enough air. The installer on my system had installed dampers in each of the various outputs from the air handler, so it was a simple matter of partly closing down those lines that were closer to the handler, forcing the air into the longer lines. A bit of trail and error was all that was needed to get a uniform temperature throughout the house.

The advantage of having the dampers at the handler is that you don’t get the noise problem that comes from partially closing down the individual registers, or the problem with someone opening the registers and messing up your flow balancing. These dampers were not something I had asked for extra, but just part of the standard installation from my HVAC contractor. They may be on yours as well.

View Sawkerf's profile


1730 posts in 3337 days

#15 posted 02-11-2010 06:43 PM

Rick -
Reading your posts, I think that you’re dealing with two – very separate – issues here. The first is the system balance which would give you fairly uniform temperatures throughout the house. You’ll get that by partially closing registers in the short duct runs and making sure that the longest runs are fully open. It will take a while to get them “tweaked”, but that’s necessary. You should also know that you may have to do it all over again when you start using the AC instead of the heat.

The second issue is the noise at the return duct. That isn’t about your flow balance, it’s about the volume of air being drawn into the return. Those noises are often due to vibration in the ducting, the return grill, or maybe the straps that hang the duct. When you added that filter, you substantially increased the pressure differential at the grill. This raised the air velocity through the grill louvres and filter which raised the noise level. Unless your system is designed to have a fliter at the return grill, you should find other ways to reduce the noise. Your HVAC guys are probably the best way to do that.

-- Adversity doesn't build reveals it.

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