I've got a carrier rtu that just recently ( in the last 6 months or so is eating up belts. I find the blower pulley and motor sheave on fire (really hot) and belts are worn and really hard showing signs on excessive heat. The sheaves are aligned with a straight edge and the pulley and sheave are a little worn but I've seen a lot worse without belts shredding in 2 months. It's a constant volume unit and the 2 grooved sheave is non adjustable. The blower runs 24/7. I'm going to install a new pulley and sheave. Any thoughts.
Carrier
M/N-48EJE054---
S/N-3202F71910
If you were located in Philadelphia I would know the exact unit you are working on.
As far as I can tell this is a bad design. I considered recommending to the client that we go to a three belt system and up size from the vx belts to a B, but they wouldn't pay anything close to what it would cost to do that.
My second idea was a soft starter but that too, would be too much money for them.
[Avatar photo from a Florida training accident. Everyone walked away.] 2 Tim 3:16-17
Use a sheave gauge to judge wear on both sheaves. With distance in photo it is hard to tell, but it looks like belts are riding too low in sheave. So that's either wear or wrong belts. Are the tops of the new belts flush with the outside of the sheave or above, then good. If not, then its wear or wrong belts. A sheave gauge will also give you the correct belt size. Are you sure that the sheaves are tight on the shafts? What does it sound like on startup? Something changed as you said this is a recent development. Don't take what belt size you found on it as correct.
The sheaves need to match the belts and it looks like you have a VX belt there. Use cog belts, what you showed is not a cog. Tighten 1/64 in. per inch of span or get a belt gauge and the data to go with it for tightening.
How much slop do you have in the blower and motor bearings? How tight do you run the belt? The official value is 1/64th" deflection for every inch of span. Practically, I find that so long as the belt is tight enough to not slip on start up and loose enough that you aren't putting undue strain on the bearing you are good to go.
How hot was the motor? Is the name-plate sticker discoloured at all?
If you were located in Philadelphia I would know the exact unit you are working on.
As far as I can tell this is a bad design. I considered recommending to the client that we go to a three belt system and up size from the vx belts to a B, but they wouldn't pay anything close to what it would cost to do that.
My second idea was a soft starter but that too, would be too much money for them.
Is a bad design for sure! the motor frame holding bolts strip and the distance between the sheaves is way too small, double the belts, increase the distance and beef up the bolts.
How much slop do you have in the blower and motor bearings? How tight do you run the belt? The official value is 1/64th" deflection for every inch of span. Practically, I find that so long as the belt is tight enough to not slip on start up and loose enough that you aren't putting undue strain on the bearing you are good to go.
How hot was the motor? Is the name-plate sticker discoloured at all?
All that is fine, if, I repeat, IF the drive was properly engineered. I can tell you from the sheave temps that the load on the belts is too great for their temp dissipation. I was replacing belts on one of these units for five years when we severed our relationship with this client due to a bankruptcy where we lost many thousands in unpaid invoices for repairs at their stores and warehouse. The unit in question cools their main offices at the Philly location.
Two 5VX belts on a 20 hp motor. That's nuts.
[Avatar photo from a Florida training accident. Everyone walked away.] 2 Tim 3:16-17
Surely Browning wouldn't let that out if it was a poor design?
Originally Posted by valdelocc
Is a bad design for sure! the motor frame holding bolts strip and the distance between the sheaves is way too small, double the belts, increase the distance and beef up the bolts.
Surely Browning wouldn't let that out if it was a poor design?
The funny thing is that "Browning" is just a stamp on "Carlyle" products, no that there is anything wrong with that, the real problem is unit manufacturers cutting corners to save $$$
Had issues with multiple units on a roof doing the same thing. Had Carrier rep look at it and their answer was tighten the belts more than what we presently had. It solved the issue, but who knows what hell that played on the bearings. There were other units on the roof, basically the same but which had VFDs never tore through belts.
This unit is 1 out of 4 of the same model unit that is giving me grief. The belts are tight. There's no squeal at startup but they started to overheat and the customer could smell the burning throughout the store within a couple hours.
sounds like too much cut on the corners. i have had many trane air handlers have this issue. in most, i beefed up the number of belts, lengthened the belts as much as would be allowed and stiffened the frame...no more issues. one unit actually cracked the frame work. the maintenance staff kept replacing the belts...lots of belt boogers in the bottom of the unit. I took off a different panel and you could see the huge crack in the frame. it turned out that as the unit went to start up (BI fan, high speed) the motor would climb the belts and the belts would get chewed up due to lack of tension.
"Right" is not the same as "Wise".
Don't step on my favorite part of the Constitution just to point out your favorite part.
Just because you can measure it, doesn't mean it is important. Just because you can't measure it, doesn't mean it isn't important.
sounds like too much cut on the corners. i have had many trane air handlers have this issue. in most, i beefed up the number of belts, lengthened the belts as much as would be allowed and stiffened the frame...no more issues. one unit actually cracked the frame work. the maintenance staff kept replacing the belts...lots of belt boogers in the bottom of the unit. I took off a different panel and you could see the huge crack in the frame. it turned out that as the unit went to start up (BI fan, high speed) the motor would climb the belts and the belts would get chewed up due to lack of tension.
Funny that I had an air handler do almost the same thing. Replaced the frame and the blower wheel/housing since it blew up too. Since then no such problems.
I had run into this problem before it was a burning smell complaint when i when there everything was red hot motor and pulley checked everything found my indoor motor was pulling very high amps i replaced the motor and everything worked properly id also check the blower assembly to check the bearings for play
Not enough belt cross section or length.
Not enough belts.
Not enough sheave metal mass.
You can make them tight so that they don't squeal at startup, but in this case, you are going to stress the bearings. However, you can't make up for the friction of contact and flexing, and the lack of mass for heat dissipation.
Cheap.
[Avatar photo from a Florida training accident. Everyone walked away.] 2 Tim 3:16-17
I had a new indoor packaged unit that ate up the belts, took a close look at it, both fans were installed backwards at the factory. T & B had maxed out the pulleys to get the airflow up. BTW it was a B**** to flip the fan wheels.
I had a Carrier air handler that would eat belts like it was its job. it had to B32 belts and the pulleys were almost touching so the belts had no cooling off time between the pulleys and were overheating. Belts would dry out and crack within a month and the unit would start shaking the booze off the wall of the bar. Tried every brand and nothing held up untill I stumbled across Carlisle Super II/ RawEdge belts. Oddly enough they are made in China and fairly cheaply priced, but they are far better than anything else, even the German belts. These belts go 12 months in that unit, where other belts would be lucky to go a month. I have switched to them exclusively and have cut belt issues to pretty much nothing. I have never had one break, crack, or chunk.
Having the same problem with Carrier air handler 42BHE.
I installed 8 units less than a year ago.
I had to replace 5 belts on 4 units already. One unit I did twice aleady.
Having the same problem with Carrier air handler 42BHE.
I installed 8 units less than a year ago.
I had to replace 5 belts on 4 units already. One unit I did twice already. Check out pics of 2 belts from 2 different air handlers.
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Originally Posted by timebuilder
