New gas furnace fan motor noise through the return

[MominTN]

I have a new HVAC 90 Plus high efficiency upflow gas furnace that was installed 3 days ago. It makes a high pitch noise that sounds like a very small hairdryer on high which I assume to be the fan blower. It starts up the same time as the fan so that must be it. It reaches a constant pitch and stays on as long as the fan is on. I have metal ductwork. The noise seems to be coming out of the return. You can hear it from every room on this floor but it doesn't seem to be coming out of the vents. You also can hear it in front of the gas furnace and in the basement in general.
They have tested every vent, the static, and other things, and decided to replace the blower today. The blower they took out was very hot so we were hoping that was it. The noise still is there.
I have read some of the posts on this forum that sound similar to mine, but I can't find where anyone came back to the forum and said what resolved this problem. If you know of a resolution, please reply.
Someone on this forum said to try this to someone else but I don't know if it worked.
http://www.ecoduct.com/forms/Flexibl...0Connector.pdf
Surely other people have installed high efficiency units on metal ductwork and gotten rid of this air blower noise.

[clarkie]

If you don't have enough return air inlets ducted back to the furnace and possibly thru an undersized return air trunkline, this would produce a loud noise. Maybe you don't have enough return air?
Especially if is is an ECM fan motor!

[MominTN]

The return is 20" X 30" (size of filter). There is a plumbing pipe running down the middle. There is a square hole behind it as the house was constructed around this return. Looking down, it appears that the return ductwork does not come all the way across the bottom of this hole but maybe that is just the way the returns are suppose to look. They did open and look into the return. No one mentioned a problem with the return.
The furnace is 100K BTU for 13 ducts downstairs and a small duct in an upstairs closet. Downstairs is around 1721 sq ft.
Can a return be added in a wall? Or do you need to have more space?
They are now talking about some type of canvas connector.
I would really like to know how other people resolved a similar problem. I also am curious how many people are still using metal ductwork with the new high efficiency units and if they are quieter or noisier than the old ones.

[phbsales]

The noise you may be hearing as you described "a high pitch like a hairdryer" would be the draft inducer motor.

I'm also wondering, did your HVAC service provider do a load calculation on your home? I am a bit north of you and I plugged your square footage in to my own numbers in for my region, and I'm wondering if 100K btu is too big for your home. That could also present noise issues.

JMHO........

[beenthere]

What was the static when they tested it?

[MominTN]

What was the static when they tested it?

Don't know. They said it was okay.

All 5 estimates gave me prices for 100K btu. I had 125K btu on the old 21 yr old Heil.

[beenthere]

When they say its ok. And don't leave a record of it.
Well. They may not have checked it.

[wisconsinapp]

Its definately not any type of problem to have metal ductwork. I think that is probably the only CORRECT way to do it. Sure you could use other materials, but sheet metal is the best way to do it. I would have to agree and say its either your inducer motor, or not enough returns, a quick easy and not so right fix to that, would be to cut a register into your return drop in the basement, but that would be the installing companys problem, not yours.

[cook42]

I was wondering if when the furnace shuts off that if you hear a slight thump sound from your return duct if so I would check to see if the return duct is sized right.

And if that motor is hot like you say it sounds like to me that the motor is working hard to bring back return air to your unit.

I was always told that that the cfm that is deliverd to the space that the same amount must come back to the unit.

I would have them check the size of the return duct and also how many cfm's is being deliverd to your space.

[viessmann]

high pitch noise is coming from return grill or grills very common on new installs with 90%or higher try and remove grill to see if noise goes away i pretty much have to add extra return ducts and grilles to the retrofits i do in the old homes for what ever reason half the older homes never had any returns in the basements and when the dumbasses renovate the basements guess what they forget

[Pelican3]

I have two questions.

1. Did they do a temperature rise on your install? They might have recorded the results in the instalation manual. Check what they are and compare them to the rating plate on the furnace.

2. Does the furnace still make the noise when you pull the filter out? A lot of the expensive HEPA filters like 3M and others are very restrictive, resulting in high pitched noises as the blower sucks air in from around the base of the furnace as well as the filter door area. We recommend to our customers to buy the cheapest filter available, like the ones you can see through.

[clarkie]

That's a pretty bad info you are giving to your customers about buying the cheapest air filter available that you can see thru. I guess you don't mind about your customers recirculating the household dirt thru the HVAC equipment, clogging up the evaporator coil, blower wheel and motor, heat exchanger, ductwork, etc.
Come on man, a decent pleated air filter should be the least type of air filter recommended to a homeowner.

[Pelican3]

Is it bad advise? I really don't think that they contribute to clogged eveaporator coils. If you get your furnaced serviced yearly then buildup of dust on the blower motor and fan is not an issue. I find that the pleated filters cause more damage than what they are worth. They might be ok for day 1, but after that they are very restrictive and contribute to very high temperature rises, furnaces going off on limit, and cracked heat exchangers because of the high temperature. Don't be so quick to judge.