Air handler blower motor

[rkusek]

After only 5 years it appears I have bearing going out on my blower motor. It has a definite shimmy on high speed and the fan wobbles as it comes to a stop. I can feel the play too. I was able to get rid of the shimmy by connecting the low speed wire vs. the high speed. Now it just has the little extra groan on startup. Lennox is pretty secretive about their parts and most local suppliers either didn't have it or told me I had to call a HVAC contractor. One of them did give me the part number and I was able to find it online for $271 vs. 4-500 bucks elsewhere. I always thought it would be a good idea to have a spare so hopefully the bearing is replaceable on the old one. For those of you with boilers using a HX with forced air do you run on high or low? I think typically most are setup to cool on high and heat on low. Mine was wired on high exclusively (I guess because it's a heat pump) although the last couple winters I would manually switch it to the low speed wire when using the wood boiler. Does anyone see a problem with me adding a relay (rated for the proper current) to switch speeds from low to high based on whether the wood tstat or heat pump tstat circuitry is activated? The heat pump currently has priority over the wood tstat. I always run the heat pump tsat a few degrees lower. So if the heat pump was running and met it's setting while the boiler water reached temp my new relay would switch from the high to the low setting while the fan is still turning. Switching speeds while blower is turning should not be a problem should it as long as only 1 motor speed winding is energized at a time since this would be the case with my proposed new relay, right?

 

[heaterman]

Parts availability and prices are a couple of the things I do not appreciate about Lennox. A lot of their stuff is proprietary in nature and you have to go through one of their distributors or dealers to get you hands on whatever you are looking for.
A multi speed motor for a typical air handle in the 4-5 Ton range should cost about $150-$200. If you have a variable speed blower motor (ECM) you can expect to pay about double that amount. Efficiency comes at a price.

 

[rkusek]

Got the blower motor changed Saturday. Had to heat the hub on the blower to get the motor free. Other than being 2 speed instead of 3 everything was the same. Bearings on old one have play but hopefully can fix it for spare. I think I'm going to add the relay to switch to low speed when the wood tstat ckt is active and high speed as the default for heat pump operation. Currently hardwired for low and noticibly quieter plus with the eko fan at 50% boiler hovering steady at 168. Not much idling here today with -11F temps and -35F wind chills

 

[MarkW]

I put a HX in place of former propane furnace and added the blower from a 3t system. I run it on low speed of the 3 speed motor. I can't see any downside to adding the relay. It's not as if the system will know the difference.
I can't imagine running my blower on high. It's putting out a tremendous amount of cfm buy it's only heating 1100sq ft, atm. Quieter is better, too.