York TY chiller trouble

cartercrew · Oct 13, 2005

I am trying to figure out what is wrong with a 15 year old York YT centrifugal chiller, 525 ton capacity. The chiller is designed for a 5 deg. delta t on evap side. Here are the conditions that I think are relevant : Evaporator entering water temp:55, leaving water temp:55, condenser entering water temp: 69.5, leaving temp: 71, Suction pressure 8 PSIA, discharge pressure 25 PSIA, Saturated suction and discharge temps were reading correct according to the P/T chart (I can't remember the exact temps though. These readings were taken just before the chiller shut down on a probe error, after running for 10 minutes. It was surging the whole time it was running. The chiller has both freq drive and guide vanes, but both were at 100%.

I have checked and cleaned the cooling tower, inlet strainer, and punched the tubes. The tubes looked clean, but I brushed them anyway. I don't think this is a water flow issue, since I am not getting any temp drop across either barrel. If the water was not moving fast enough, I would expect to see a big delta t.

Luckily it is the end of the cooling season in South Carolina, so I don't need two chillers. I am able to shut this one down and figure it out.

If anyone has a direction to point me in, please advise.

wacko · Oct 13, 2005

Do you mean PSIA or PSIG?
Also, which refrigerant?
What are you using to measure temps and pressures?

chill factor · Oct 14, 2005

have you checked the accuracy of your probes?

absrbrtek · Oct 14, 2005

Your machines got non condensables in it. 10 PSIG is way to high for 71F leaving water and clean tubes. On R11 you should be around 2.8" and R123 6.5" of vacuum on the high side. Fix your purge or your leaks or both.

drivewizard · Oct 14, 2005

If you have lots o air in unit you will get a evap transducer failure diag. after 10 minutes of running.

acjourneyman · Oct 14, 2005

I agree,air.

absrbrtek · Oct 14, 2005

Agree, pull the leaving chilled water sensor out and run the machine as hard as you can without it surging. It will stay online then.Just keep an eye on it while you run it this way. This way the purge has time to work and get the air out.

drivewizard said:
If you have lots o air in unit you will get a evap transducer failure diag. after 10 minutes of running.

cartercrew · Oct 14, 2005

This chiller uses R-123. The pressure readings are in PSIA. I have checked probe and transducer error through component replacement, and the new sensors read the same as the old ones. I will try again to get the chiller to run and see if it is purging a lot. In the past with this chiller, when there was alot of air in the condenser, the condenser pressure and saturated refrigerant temp would be way off. The pressure would be high with a low sat temp. This time though, the pressure matches the saturated temp.

Randy S. · Oct 14, 2005

Air is the culprit

It's typical for this type of fault indication.

Check the liquid return line from the purge to the evap. It should feel cold while the machine is running. If not, you'll need to check the orifice where the liquid line from the botttom of the drop leg comes into the top of the purge canister. A plugged orifice will make the purge almost non-functional.

Then you need to find the leak. The round plate on the drop leg is a famous leak point, and the vent solenoid bonnet nut on the top of the volute is another. I've also seen dry shaft seals leak, so a look at seal cavity pressure would be in order and maybe a quick check of low speed thrust while you're in the neighborhood. The suction L bolts may need snugging up, too.

Good luck...

drivewizard · Oct 15, 2005

Ya gotta get the air out. After you fix the leak.

The York Turbo-gard purge is an awesome purge under the following conditions:
1. You have a really tight machine with no leaks and no air in it!

2. The chiller is running!

Any thing other than those conditions and you are screwed.

You need to cowboy up and install a purifier purge, have done lots of them on YT's. Customers love them, they can now get and keep the air out with out having to run chiller.

chiller mekanik · Oct 15, 2005

burp it

Like everyone else is saying, you've got air.

This would be a real good time to have a portable [spare] condensing purge unit.

If you don't have one, you may be able to trick the purge on the other machine into removing enough non-condensibles to get this thing to run. [with some long hoses & a little bit of imagination]

Clearly its time to look for leaks as well.

Also be open minded to a purge malfunction.

If you find yourself in the market for a condensing purge, [which I would only consider replacing that purge if there was a major failure] the purifier purge by Trane is an excellent purge but, I would also check with Reddipurge & Reftech.

Besides price & availability, I would also try to determine which one would be the easiest to install.

cartercrew · Oct 15, 2005

Thanks, I'll try the suggestions Monday. I know that I will not be able to buy the condensing purge unit, since there is a project to replace both of the chillers (and the building that they are in) with in the next two years.

I guess what is still confusing me on this deal is the fact that the saturated refrigerant temp in the condenser is what it should be for the given condenser pressure. Every time I have had an air problem in these units before, there has always been a large differance between them.

cartercrew · Oct 19, 2005

Still running...

After three days of running, the chiller is still on line. I had to let the water loop temp get up to about 60 before I was able to get the chiller to stay on line with out surging. I let it run, limited to about 50% vane position. Tomorrow I will put it back into normal operation to see what happens. Thanks for the help.

York TY chiller trouble

cartercrew

wacko

chill factor

absrbrtek

drivewizard

acjourneyman

absrbrtek

cartercrew

Randy S.

drivewizard

chiller mekanik

cartercrew

cartercrew

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