Wed 1 Jan, 2014 06:49 pm
Had a 1/6 hp furnace blower motor designated Motor Type FH (for split phase), meaning it has a start winding and a running winding.
New motor is 1/3 hp and not designated split phase (has only one winding) and each time it starts, there is a short electrical noise, hard to describe, kinda like a dog bark, for less than 1 second, but can hear it anywhere in the house.
If the original motor had a startup sound, it was not noticeable. Both motors are 1725 rpm.
What is the purpose of having two motor windings and would lack of a startup winding be related to this dog bark at startup?
A split-phase motor has a higher starting torque although since you went with a higher HP motor I don't know that would be an issue between the two. Your larger motor will have a higher in-rush current on starting. Is it possible there is something that vibrates when the furnace starts? Conductors can vibrate when there is an in-rush of current. I would check to see everything is secure and see if that helps.
This is completely correct, except that I would add that the higher HP motor will have a higher torque than the previous motor given the size difference. I'm thinking that you are hearing more of a chirp than a bark, which can be tied to the belt initially slipping at start up. Check the belt tension, and wear.