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-   -   Forced air furnace blowers making noise (http://www.diychatroom.com/f17/forced-air-furnace-blowers-making-noise-32506/)

CowboyAndy 11-24-2008 06:28 AM

Forced air furnace blowers making noise
 
Hey all, I have a problem with my newly installed Newmac cl86 wood/oil furnace.

Right after we installed it, we had a problem where the blowers sounded like they had marbles in it, turned out it was slightly off kilter, but now is dead on balls level.

Last night (this morning, actually) out of nowhere, it started making this "grinding gears" sound. The blowers would come on and sound normally, then the "marbles" sound would start building up gradually and after a few seconds sounds like grinding gears and would start the sequence of sounds over until they shut off. I went down to investigate, but being half asleep and not knowing much about hvac anyways, the only thing I did was tighten up the drive belt (which seemed loose). I checked, and it is still level.

the next few times it came on it was okay, sounded normal. After about a half hour, it started again, first with "marbles" then "grinding gears". Finally, it just had a slight "marbles" sound to it.

Any Ideas?

BTW, for what its worth the firnace was bought new in august and installed by my brother in law, who went to college for hvac, but is pretty new to the game.

javan 11-24-2008 09:35 AM

Was this new furnace installed utilizing existing ductwork?

Could it be a static pressure problem? (Fan too powerful for existing D/W?)

Just a few thoughts...

CowboyAndy 11-24-2008 10:21 AM

Quote:

Originally Posted by javan (Post 189415)
Was this new furnace installed utilizing existing ductwork?

Could it be a static pressure problem? (Fan too powerful for existing D/W?)

Just a few thoughts...

yes, it was installed with existing ductwork.


Can you explain how that would cause a problem? What about the fact that it has been fine for almost 2 months, but now there is a problem?

javan 11-24-2008 11:43 AM

Sorry, missed that part about the time-frame.

Now, I am curious. How long did it run before you fixed the level issue? Any chance that you damaged the bearings?

Regarding the ductwork question. Look at the installation manual and see where it talks about D/W connections. Depending on the rating of the furnace (CFM) and the size of the D/W connection, your fan may be trying to put too much air into the duct, but you would have this problem everytime the fan goes to high speed (assuming that you have a variable speed fan).

CowboyAndy 11-24-2008 12:07 PM

Quote:

Originally Posted by javan (Post 189468)
Sorry, missed that part about the time-frame.

Now, I am curious. How long did it run before you fixed the level issue? Any chance that you damaged the bearings?

Regarding the ductwork question. Look at the installation manual and see where it talks about D/W connections. Depending on the rating of the furnace (CFM) and the size of the D/W connection, your fan may be trying to put too much air into the duct, but you would have this problem everytime the fan goes to high speed (assuming that you have a variable speed fan).

It was only about a day when it made noise the first time, about a week after we installed it. It has been well over a month since then.

Im not sure if its a variable speed fan, I couldnt find anything in the manual about it. As far as I can tell, it only runs one speed.

Mainah 11-24-2008 04:48 PM

Make sure the pulley's are tight on both shafts-

kennzz05 11-25-2008 02:49 AM

turn off the power and feel both sides of the blower wheel in relation to the housing(the part where its curved inwards) sounds like the wheel is dragging the housing and needs to be realigned on the shaft. if it is than loosen the set screw on the wheel and hold the pulley to lock the shaft, than work(turn) the wheel back and forth with your hand while gently pulling at the same time in the direction you need to move it. hopefully being new it will move fairly easy. make sure you almost back the set screw all the way out so it dosent drag the shaft and score it,being careful not to drop it(the set screw) or you may have to pull the blr/assm. to retrieve it also the fan blades can be sharp if you have any mechanics gloves id wear them

CowboyAndy 11-25-2008 07:07 AM

Well, sometimes the simplest explination is the one...

I took off the access panel, and staring me in the face was the set screw for the pulley, sitting right there on the ground. Damn thing worked itself all the way out!

Can I put a dab of thread lock on it?

pipefitter636 11-25-2008 05:04 PM

Quote:

Originally Posted by CowboyAndy (Post 189864)
Well, sometimes the simplest explination is the one...

I took off the access panel, and staring me in the face was the set screw for the pulley, sitting right there on the ground. Damn thing worked itself all the way out!

Can I put a dab of thread lock on it?

Use the blue thread lock not the red, one day you will have to replace the pulley. With the red you will need a torch to remove the set screw.

kennzz05 11-26-2008 01:56 AM

Quote:

Originally Posted by CowboyAndy (Post 189864)
Well, sometimes the simplest explination is the one...

I took off the access panel, and staring me in the face was the set screw for the pulley, sitting right there on the ground. Damn thing worked itself all the way out!

Can I put a dab of thread lock on it?


:thumbup::thumbup:


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