Poorly machined impeller, CVHF
My contact in Lacrosse has retired so now I'm forced to go through the normal channels & talk with the regular tech support guys. (bummer)
This was the first time I've called up there in over 5 years. Now there is a special toll free number for all of us regular schmucks & a serial number is required for each question.
I'm trying to measure the impeller to diffuser wall clearance with the straight edge which is suppose to be .000 to .005. I have measurements as high as .038 & as low as .014. No matter where you take this reading, its different. (these were also the measurements during disassembly)
My only purpose for calling them was to inquire about this sloppy machine job & find out if this was the norm for these impellers in the extended capacity machines.
I've seen this before, just never this bad. In the past I've adjusted the shims to put the low spots behind the wall & keep the high spots no higher than .005. Obviously, with my differences the way they are, I'm gonna be way negative with the low spots. I haven't checked the depth of the track but rest assure I will know the thickness of the inner impeller wall & the depth of the track going forward monday. Maybe I'm making too much out of this, who knows?.
I guess the most annoying thing about my call was the excessive questions:
Have you talked to the local office about this? (are you kidding me?)
Why were you inclined to tear this machine down?
Are you sure the bearings were bad?
Did the local office participate in the diagnosis? (are you kidding me?)
Then he wants to know what type of thrust bearing clamping system I have. I tell him I have the flat ring that bolts to the bearing bracket. Then he tells me there is a modification for these extended capacity machines. A newly disigned bearing bracket that takes a different type of mounting ring that is suppose to have less chance of distorting the bearing race. I ask if there is a bulletin. He tells me I have to go through the local office. Are you kidding me?!?!?
Of course this modification is costly but it reduces the chances of pre mature bearing failure. I guess my question at this point is: How is this a modification & not a recall??
Either way, if I want to persue the new & improved bearing bracket/clamping system, I have to go through the local office. Like thats gonna happen.
Has anyone heard of this?
I've got other sources I'm checking with & if I find anything worth adding I'll do so.
As far as the sloppy machine job on the impeller goes, I have to conclude that its normal because I wasn't going to get a specific answer. What a P.I.T.A. this whole ordeal was.
Of course I'm sure he took my reluctance to be too specific or answer all of his questions in a completely forthcoming manner as a sign of incompetance.
If all of a sudden I find the local office involved, I will blow a gasket.
All my leon freaked out!
I just overhauled a cvhf1280 beefed up to 1400, I had the same issues with the impellers. I was told as long as they dont rub (diffuser or casing etc.) then there is no real issues other than being out of spec. When you say extended capacity are you talking 1720?
instead of answering your question they just want to insult your intelligent. did they ever answer your question? too bad you couldnt reach in to the phone and slap him
If it didn't rub before I would say you are good to go, as you know, just don't shim it out to wear the volute may contact it.You have to remember those impellars are very large and very light so it would almost be impossible to get one dead true.I too have heard about the new bearing requirements but I have not yet done an extended capacity thrust bearing so I haven't gone any further with the info. What is the first 4 digits of the serial # ?
I just sent you an email hope you dont mind.
Your probably ok going back togethor with the original retention method. I have not seen a Service bulletin yet on this, although have heard rumors of the "crush Ring" retention method being implemented in the future.
sorry about the tech support. but they want you to contact the local office so that we have to deal with you . seriously though, they have to deal with Goober's Heating, Cooling, Small Engine Repair and Taxidermy. so it's easier to pawn everyone off on the local office. unfortunately, good techs, like yourself, fall into the cracks that the planet-wide descions that trane (or any other manfacturer for that matter) has to make. and sometimes the local office has less experience combined than some of the techs that are forced to call have.
most of trane's tech support is top notch though.
99% of the time, YOU will probably have better luck posting here than calling tech support if you can wait...we know your level!!
i guess that i am not sure which measurement you are taking for sure...the "impeller diameter to diffuser" radial clearance or the impeller "inner plane" to diffuser surface?
I'm pretty sure he was talking about how much the impeller sticks out past the diffuser face, not the radial as indicated by the clearance he was shooting for - .000 to .005
You would denfinitely have problems if that was your radial on the impeller to diffuser edge wall.
Anyway I have also seen this measurement out of whack too, basically boils down to sloppy machine and or casting work. I would try to keep on the + side, in other words don't have the discharge gas hitting the diffuser. Of course there will come a time where you might wind up shimming the impeller out to far and cause some other problems going back together. I measure all that I can coming apart and then going back see what you can improve upon.
Originally Posted by jayguy
Thanks for the kind words
I mean it, you guys are great.
I kinda feel like a $hit head now, but I know you guys understand that I was just venting.
There have been times when Trane has really come through for me. But good or bad, we all know it comes down to people. In other words, one day a good guy will answer the phone & another day a not so good guy will answer the phone.
Turbo is right, its the amount that the inner impeller wall sticks out past the diffuser wall.
I'll post what I come up with. I'll also post some pics, got quite a few on this one.
All my leon freaked out!
There is a service Alert and a updated service bulletin regarding the thrusts on CVHF
bearings CTV-SVA13A-EN and CVHESB33C-0603 have fun trying to get them.
keep in mind that during disassembly there may be some crap between the impeller and the shaft that can cause a little wobble during disassembly. also, you no longer have the pressure of the nut forcing it on straight.
in the tear down class, they also said that the machine gets put together ONCE at the factory. they do not remove the impellers to re-shim. so Dave Andressen said to measure while tearing apart so that you can make it better when you put it back together. he also said that if the impeller becomes negative, you can get some whistling. if it is too positive, you can lose some effeciency.
bearing bracket retrofit
I can tell you if you do not get the new retrofit parts you can plan on a wrecked machine! One of our techs replaced the outboard bearings with out pre load of 2800# and no crush ring and of course no new bearing support housing,the 1470 cvhf ran 3 months the bearing cages broke and the impellers dug in the walls really nicely,the retrofit kit would have saved us alot of time and labor .Oh and yes it was a total coverage job!!!!!!!!!!!!