Carrier 30HX series motor cooling control

[Gibbo]

Your log doesn't seem too bad apart from the EXV position being quite high anything over 60% would normally mean low charge. but your liquid level is good and at setpoint of 1.8.
The chilled water temperature approach of 3 is also good both indicating charge is not that low. Why do you think the charge is low ? You could try pulling the charge to confirm it.
With the log you gave us it is hard to see why your tripping on low discharge superheat when your reading of 30 F doesn't seem to be a problem.
Motor temperature is ok at 162 F
How does this log compare to B circuit.
Why is the Discharge pressure high ?

[Dallas Duster]

Discharge pressure seems about right I have seen worse on some GX`s.

[Gibbo]

Morning to you TGL Hope all is well in cowboy country.

With condenser water on at 25 C and chilled water almost at setpoint i wouldn't expect to have 177psi but maybe you guys operate systems differently. Any idea what ambient they would have onsite.

As for GX's yes they can be higher, you may want to check the SCT setpoint isn't set higher than 40 C.

I appreciate you guys have much better weather than over here, I have only just got my shorts and flip flops out of storage.

G.

[Dallas Duster]

Do you Englander's not have any HXA's over there I think you have it confused for a HXC? I did see 2 HXC's recently running 165ish and that was normal for these people.

[Gibbo]

Apoligies TGL

I lost the plot abit with the HXA, somehow thought it was a HXC we were
talking about. Not enough Guinness being drunk to lubricate the brain i guess.
Thanks for keeping me on track. I still think its a bit on the high side
pressure wise.
As for being an Englander, i just happen to live in England i am originally from
Scotland.

[Dallas Duster]

No apology neccessary I forgot to put one of these in there. I had a felling you were thinking the other. I was just busting your balls. How is Europe these days ? Do you ever get to go across the channel much ?

[Gibbo]

I don't get over so much these days, used to visit our factory in France a few years back and enjoyed it very much i liked the lifstyle as i am a fairly laid back guy. Syracuse in winter was something else though. Still the guinness helped.

[chilbrig]

You may need to download the operating program again into the chiller. I had this problem on a 30GX, and the download solved it.

[chillerguy81]

Hi Guys, sorry it took me a little while to get back to your replies.

Gibbo, your right the log I took doesn't look too bad. Chiller was running fine at that time till I walked away from it, this has been an intermittant problem. I have seen the motor cooling solenoid cycled do to no apparent reason, motor temp way lower than setpoint. Suspect low charge do to exv position, and the condition of the machine. It's a known leaker, oil all over the place do to high pressure problems, due to condenser airflow issues, and the list go's on Poor installation at its best. Just working on getting them through the summer for now.

I returned to sight yesterday and added some charge to get the exv position down. After charge was added ran this circuit for approx. four hours and she ran great without tripping out. Double checked all transducers and thermistors, all look good. Noticed that motor cooling begins pulsing when the navigator reads 160.5*? This is lower than I expected with a setpoint of 200*, but I wasn't sure what kind of differential there is. I'm still kinda leaning towards some kind of funky software issue, but I'll just have to keep an eye on it for know. I'll let you guys know what happens.

Thanks again for the input, have fun out there!

[chillerguy81]

Chilbrig thanks for the info....interesting.

[Gibbo]

Just interested how much extra refrigerant was added and what was the charge supposed to be ?

Regarding the software issue the Carrier Factory Software will have been upgraded since your chiller was made probably more than once this happens for various reasons to correct problems found in the field through feed back to the factory and is the same with all manufacturers.
The downside is you would have to pay Carrier to come out to download the new software and run and test the operation of the chiller well worth it if you suspect there are certain control issues your not happy with.

At the very least check what version software you have onsite then ring Carrier and ask what is the latest version for your chiller.

Hope it all goes well for you.

G

[chillerguy81]

Gibbo,

From the documentation I found in Carrier's original job book it looks like the charge was 285 lbs per circuit. The remote condensers are slightly oversized and the lineset is maybe 50 ft. (Thats just a guess) I added 30 lbs of charge which maintained the liquid level setpoint and got the exv position down to about 50%. I'll check on the software updates, thanks for the input.

[Gibbo]

Well done mate seems your on the right line.

G.