Hey guys I have 2 YS chillers when they shut off they run backwards as the gas equalizes. I know this is bad on the thrust bearings and rotors. I'm thinking the check valves are stuck open! Any field fixes to free them up?
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Hey guys I have 2 YS chillers when they shut off they run backwards as the gas equalizes. I know this is bad on the thrust bearings and rotors. I'm thinking the check valves are stuck open! Any field fixes to free them up?
Somewhere in the evolution of the YS (pre-Optiview) they made upgrades to the eprom so that when the temperature was satisfied or the chiller was given a stop command the slide valve would "close" so it wouldn't get "stuck" at >30% which would prevent a restart. I think this would also either eliminate or minimize backspin. That would be a couple hundred dollar fix rather than a few thousand dollar fix.
When asking a question please give more information...i.e. model number, type of control panel, etc. It makes it a little easier if we don't have to guess.
KnewYork, does this upgrade position the slide valve before or after the compressor is commanded to stop? In other words, is it part of a pre-shutdown sequence? I don't have Steve's problem, but I have seen mine experience an inadvertant shutdown (BAS, run enabled related), and then have to wait several minutes for the slide valve to slowly move, to allow a start. They are pre-Optiview units. YS DB DA S2-CJA.
It positions it before shutdown on any cycling shutdown (i.e. temperature is satisfied). It won't do it if there's a safety shutdown. When York realized they had some sticking slide valves this was one of the methods used to combat it. If one were to order an eprom for a YS single line panel they would get the latest revision that includes this feature. I'll see if I have the service information letter on it.
The eprom version where the close slide valve feature came into being is S.01F.17. Those familiar with York products know this is on the sticker (along with the P/N) that is put on the eprom.
Here is the quote from SB18 (298). "In previoes eprom versions, the slide valve unload solenoid valve is energized (opened) at the completion of the two minute lockout period after a chiller shutdown. In this version, if the microbaord program jumper J4 is removed, the unload solenoid valve is energized coincident with the compressor turnoff. In addition to this new feature, the previous features as detailed in service manual 160.47-M2, Figure 31A are retained when this jumper is removed as follows:
1. Hot gas bypass operation is enabled.
2. 30% slide valve start inhibit."
Thank you. I will see if I can identify what eproms I have. Hopefully we will hear from the OP soon, as to whether or not this helps him.
Ok we have 2 differant m/# YS DC DB S2 CJA, S/# SAAM922902, control 371-1200-003 and a YS DC CB S2 CJA, S/# SAAM 922904, same controller. Here is a factor we also have is our building is controlled by a Siemens APOGEE system that just gives an on off comand to run the chillers base on building load. So when it is told to shut off ... it does with no unload time.
Also our eproms are S.01F.11 and S.01S.05
If you have a 031-01065-000 microboard then you might want to order a new eprom 031-01102-002 which is version S.01F.17. When Siemens gives it the shutdown signal the slide valve will "close" upon receiving the shutsdown signal as long as Jumper JP4 has been removed.
Every YS Ive seen that back spins on shutdown is due to discharge checkvalve failing between compressor and oil seperator. They usually had >50k hrs on them. The disc that rides on a shaft assisted by a spring has vibrated so much that I've seen them cut shaft in two! I cant say I've seen that the back spin do any damage. On large low temp process screws they commonly place the check valve down stream of oil sperator. If they shut down on a fault, the pressure in oil seperator causes back spin until equalizes.
Only problem with this is that they're up to version 21 now, and it won't take the slide valve to 30% to trigger shutdown. It'll get you to 31% or 32% and kill the signal to the MSV and then just sit there and run until the 2 minute timeout is up and then shut down. I spoke with the electronics guru at the factory (you know him, B) and to the BPC head honcho about the problem and neither seemed interested in doing anything to correct the situation. The electronics guru infered that the whole problem was that I didn't know how to read a Fluke 87. As a result, I have two YS's sitting side by side that unload to 32% on a cycling shutdown signal and continue to run for about another minute and a half. If you use this method, make sure that your BAS will accomodate the issue with keeping the pumps on.Quote:
Originally Posted by KnewYork
As far as backspin at 30%, it will minimize the problem but probably won't correct it. I'd manually unload the thing to 30% and shut it down to see. If it helps enough, change the eprom. If not, set up the gantry. Even if you don't change the check, you'll need it to pull the compressor down when it craps out from the backspin.
Just tried to install new EPROM's REV 21. Now get error shut down code "cond no flow". We are not using a flow switch and TB 2 1 and 13 are being used for stop start by the building controller. I haven't found a way to stop this error code yet.... help?
Jumper 1 to 71 on the I/O board or put your condenser flow switch there