Furnace vibration

Badamo3521 · July 10

hey guys going to check out a ceiling mounted gas furnace tomorrow the complaint is loud vibration when the blower runs! The motor, and motor mounts, and squirrel cage have all been replaced by another tech! What should I look for and maybe silly question any units that can’t be mounted horizontally? I really have no idea what I’m walking into other than basically whole blower assembly been replaced and it’s still vibrating badly don’t know if unit manual will be there just looking for advise really

hot_rod · July 10

Easy enough to download the manual when you see the make and model. There are some indications when you look at it if it is suitable for horizontal mounting, connections on the side, pan around the A coil?

Stuff jammed in the blower wheel vanes is a common cause of the shakes.

I think of good vibrations…

mattmia2 · July 10

loose mounting, improper assembly of the new parts. loose set screws on the blower bent or damaged blower wheel, disintegrated resilient mounts.

pedmec · July 10

Depends on the type of blower. belt drive or direct drive? misalignment of the belt to sheave. improperly installed sheave. loose mounts, etc.

The classic is the wiring diagram or any papers falling into the squirrel cage.

EBEBRATT-Ed · July 10

Nobody knows until you get to the job. Who know what the other tech did, he could have bent the motor shaft or damaged the blower. What was the original call that made him replace those parts.?

mattmia2 · July 10

if it is belt drive rather than direct drive that adds a bunch of new problems, in addition to what @pedmec mentioned there are the blower bearings themselves and a bad spot in the belt is a really common source of vibration.

part of it is figuring out if the blower is really vibrating an unusual amount or if the mounting is causing the vibration to travel where it normally wouldn't because resilient parts disintegrated and it is now metal to metal or the mounting of the blower assembly or what it is mounted to is loose.

look at the blower wheel while turning by hand and see if it spins true from a bunch of directions. pull on the shaft and see if it has a lot of play in some direction, both in and out of the motor and up and down and side to side. the bearings commonly will get play only in the direction where the weight of the armature and blower wheel is sitting on them. take the belt off for this if it is belt drive because the belt can take the play out.

EdTheHeaterMan · July 10

Bob Rohr said: I think of good vibrations…

Only because you are a hot_roding Beach Boys fan!!!

I might go for the Little Duce Coupe, a 409, or that one with the little old lady from that neighborhood in California.

Seriously though, the vibrations will be self evident once you are on site. Hope it isn't the flame pulsing and someone replaced the fan parts to correct the combustion problem. How do you justify getting paid for repairs that don't solve the problem? …Nevermind, I'm sure it has to do with the blower. It's gonna be a simple fix.