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cliftonian 03-04-2012 03:29 PM

reducing noise with goodman furnace
 
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I have a small house (1100 sq ft) with a 95 % efficiency Goodman unit. The return air register makes quite a noise in the house. Lower blower speed is fine for me. So, without knowing that return duct noise has anything to do with blower speed, is it a good idea to reduce the blower speed of the furnace? Photo of existing wiring is attached. Thanks..

Plumber101 03-04-2012 03:36 PM

No it is not.

With this said the reason is that lowering the blower speed will raise temp rise and that can cause the high limit to trip causing another issue.

Best to determine what is causing the noise. Return undersized, loose metal flapping, filter dirty ect

If you measure supply temp and return temp and sub-tract return from supply this will be your temp rise.

yuri 03-04-2012 03:49 PM

Change the register to a plastic or wood one and it will be a lot quieter. Metal ones can sing. HDepot has some.

ben's plumbing 03-04-2012 05:15 PM

remove one return register at a time till you find the one that likes to sing...:yes:

Jackofall1 03-04-2012 06:21 PM

When you say, "The return air", do you mean that you only have one?

If this is the case there is a good chance you don't have enough net free area and the velocity going through the RA is too high.

With that said it sounds like you need to add some area by increasing the number of RA openings.

Mark

how 03-04-2012 07:37 PM

If the noice is from a harmonic vibration by the return air grill, then just place your hand against the grill the next time you hear this noice. If the noice lessens or stops then its sympathetic grill vibrations. If it's a metal fined grill then changing the angle of every second fin by 20 degrees with needle nose plyers will help. Wood grills create less harmonic noice but the blocky ones are often more restrictive to the air flow.
A temp rise test on the furnace is the usual test that a tech will do when dealing with a noicy return grill to determine the difference between symtom and cause.

paul52446m 03-04-2012 08:11 PM

Quote:

Originally Posted by cliftonian (Post 870190)
I have a small house (1100 sq ft) with a 95 % efficiency Goodman unit. The return air register makes quite a noise in the house. Lower blower speed is fine for me. So, without knowing that return duct noise has anything to do with blower speed, is it a good idea to reduce the blower speed of the furnace? Photo of existing wiring is attached. Thanks..

In a 1100 sq. ft. house you don't need to move that much air. I would try putting the red wire on the heat post, and then check the heat difference across the in and out of the furnace, What model do you have? How much
cooling do you have on the furnace? Paul

beenthere 03-04-2012 08:15 PM

Post full model number of the furnace. Your house may not need as much air as the furnace is moving, but the furnace may need to move that much air.

The full model number will be in the burner compartment.

Plumber101 03-04-2012 08:20 PM

Quote:

Originally Posted by paul52446m (Post 870465)
In a 1100 sq. ft. house you don't need to move that much air. I would try putting the red wire on the heat post, and then check the heat difference across the in and out of the furnace, What model do you have? How much
cooling do you have on the furnace? Paul

Please don't make any changes to the furnace as the above poster has suggested. You have a two stage heat furnace and without understanding low heat and high heat settings don't start making changes. If you start making fan speed changes and increase the temp rise without checking Delta T on both low and high heat and making sure the high limit is working these changes could be devastating.

plummen 03-04-2012 09:51 PM

If its in heating mode it should already be on its lowest speed setting.
Are your returns in the house blocked by anything? :)

Plumber101 03-04-2012 09:55 PM

Quote:

Originally Posted by plummen (Post 870574)
If its in heating mode it should already be on its lowest speed setting.
Are your returns in the house blocked by anything? :)

But it's not

From the pic

Cool tap Black wire HI Speed
High heat tap Orange wire Medium high speed
Low heat tap Blue wire Medium low speed
Park tap Red wire Low speed

cliftonian 03-05-2012 08:38 AM

thank you all for your posts. in response to the questions raised:

- the unit model # GMH95070BXA
- there is only one return air register and it is located in the hallway.

cliftonian 03-05-2012 08:40 AM

and it is only furnace; no air conditioner is connected.

ben's plumbing 03-05-2012 12:33 PM

Quote:

Originally Posted by cliftonian (Post 870822)
thank you all for your posts. in response to the questions raised:

- the unit model # GMH95070BXA
- there is only one return air register and it is located in the hallway.

how big isit......16 x25,,,16 x 20...20 x 20..

cliftonian 03-05-2012 12:50 PM

it is 20 x 20.


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