carrier 30 GT problem

[carriertech1]

have a carrier 100 ton 30gt air cooled chiller. Another one of the techs was on the machine and determined that the B circuit EXV was bad. I returned to install the EXV. Replaced and pulled down to 400 microns, also replaced both saturated suction thermistor and suction gas thermistor.Started chiller and let run for 10 minutes, pressures 200/40 and slugging both B circuit compressors with liquid. As it turns out the same problem the first tech had. Unit it maintaining 27 degrees SH but shuts EXV all the way down to do it. Called factory and they suggested to recover charge and weigh in factory charge. Returned and recovered also drained 3 gallons of oil out of cooler, weighed in 105 lbs. of R-22 and started chiller let run and found pressures doing the same thing. I know the ciller does not care what the pressure are it will shoot to maintain 30 degrees SH. I have double and triple checked all my sensors and EXV and cable I am at a loss as to why the EXV is closing and still slugging liquid, sounds like a chainsaw on start-up

[hvac3901]

three gallons of oil, holy crap, whats the 100 ton have three a circuit and two b cucuit? sound like alot of oil

'maintains 27 degrees sh...still slugging" slugging what oil?

if it sounds like a chain-saw during startup i'd be checking compressor vitals.

[hvacbear]

Forgive my ignorance but is it a flowtronic chiller?

[trimble]

How is your water flow? Do you have air in the water loop?

[freonrick]

you said your maintaining 27 degrees superheat and flooding at the same time. look in to the compressor, if it is running hot due to motor or hot gas dumping in to crankcase it will flood due to return gas sensor location. you might throttle the liquid line service valve down to stop the flooding so you can check the compressor out.

[wolfdog]

Originally posted by hvacbear
Forgive my ignorance but is it a flowtronic chiller?

A chiller made by Carrier.
Typically, multiple 06E compressors, electronic expansion valve(s) and a processor board to control it all.

[Edited by wolfdog on 08-25-2004 at 09:37 AM]

[joegrind]

does carrier want 30 deg superheat????? seems awfully high! I thought the gt were looking for 8-10?, anyways, I've been pinched in the past with similar problems only to find out i missed the slightly plugged filter/dryer!

[coolwes]

By all means get the oil back down to 1/3 sight glass.
Too much oil screws up everything.
Do you have record of oil added?
The 06E may be pumping oil due to age or damage and someone kept adding. I've seen them pump it out as fast as it was added.
Are you checking actual superheat with your thermometers or going by the chiller readout?
Be sure no sensor cables are crossed.
Check signal to EXV from processor board. 12 VDC pulsed signal to each winding. Or you can pump the circuit down, remove the EXV valve cover and go through the quick-test procedure to check EXV operation.
I have seen EXVs drive one way but not the other.
Water flow and chiller barrel condition (i.e. crushed tubes) can drive you nuts too.

[freonrick]

carrier wants 30 degrees. this includes the heat of the motor thats why it is so high. if you check the suction line temp you will find the normal super heat is about where it shoul be

[mathias]

Hello Tech.
U need to check your fuse that supplies voltage to ypur EXV board, sure sounds like your EXV is 100% open and not shutting down. If there is voltage then the driver board could be bad but make sure voltage is at the valve!!!!

[airworx]

flotronic chillers amintance around 30 degrees superheat which includes the superheat from motor windings. actual superheat is around 5 degrees depending on eprom chip.

so how are you checking superheat by looking at the processor from a laptop or are you checking sat.suction temperture and suction line temp.

flotronics run low superheat thats why they use exvs.
electronic controls keep the superheat low. so if you have 27 degrees sh taken from suction gas thermistor minus sat.suction thermistor then your not flooding its designed for it. that means if you have a loud compressor then take heads off and check discharge and suction valves if ok then see if it will pump down if not change it.

[orland25]

The you tell me the you have there,200HP and 40LP and the system go down,in 10minute ok what reason the display indicate. my friend I thing 40 is to low.

[hvacbear]

We had one similar problem changed the exv board and no problems since. The exv motor actually burned up.

[airworx]

you need to go to carrier and get a manual. suction pressure has nothing to do with. exvs maintian superheat thats it. need to know how you determined superheat by flotronic monitor or guages and thermometer.
as a guess check to see if liquid drier is not stopped up.
also what is your subcooling and whats is water temp. low water temp will drive down suction. and 27 degrees across motor is not flooding. 27 degrees by suction guage temp and suction line temp is high should be anywhere from 3 to 10 degrees depending on eprom chip.

[rob10]

What is your water Delta T and Delta P. Also, at the control panel, what is the chilled water return setpoint set at?

[cajun chiller]

I haven't worked for Carrier in over 3years and I'm not saying I'm an expert on those cheap little screws that the 30GT is,but if you are right about the 30 degrees superheat I think they are talking about discharge superheat.Suction superheat should be around 8 degrees if I remember.If you have any suction superheat you couldn't be really slugging.

[plain spoken]

Originally posted by cajun chiller
I haven't worked for Carrier in over 3years and I'm not saying I'm an expert on those cheap little screws that the 30GT is,but if you are right about the 30 degrees superheat I think they are talking about discharge superheat.Suction superheat should be around 8 degrees if I remember.If you have any suction superheat you couldn't be really slugging.

Must have been a long 3 years. 30GT is not a screw, it is a Flotronic with 06 semis. The EXV control board is trying to maintain @27 degrees superheat at the sensor. The sensor is mounted in the end of the compressor where, as mentioned above, the refrigerant has already passed over the motor and picked up internal compressor heat. In order to achive 27degrees at the sensor, the superheat of the suction entering the compressor is very low. It normally is in the 5 to 7 degree range. While this is normally considered to low, it is correct for this machine.

[raleigh,nc tech]

I recently had a new 30GTN130 chiller with comfortlink controls, not flotronic. The main base board was cracked from the factory and the chiller would not run on startup. I ordered a new board using the model and serial #'s. Installed the new board. The compressors sounded terrible on startup...lots of slugging. Had Carrier look at the problem. Found that the board had an older version of software on it. Carrier changed to a 15,000 step exv instaed of a 12,000 step exv at some point, and even though I used the model/serial the wrong version was shipped. The board thought it was controlling a different exv and really had the exvs open on startup instead of closed. Not sure if this could be similiar to your problem. Wrong exv maybe? Carrier rep said he had seen several of these mixups since the exv style change. In my case, however, I was not able to maintain 27 deg superheat.

[plain spoken]

Carrier just changed to a 15K step EXV from the 1500 it was using. On the Comfortlink boards the software can be updated in the field by Carrier personell. Actually all ComfortLink boards are the same for all the products, just different software. You can take a board out of a chiller, change the software and put it into a RTU. It sounds like a mix up at the parts counter on ordering the board.

Anyway, this is not the case with the GT, it uses an EPROM for the software. While you can put the wrong eprom in and really screw it up, new eproms do not come with replacement boards. You have to remove from the old board and install in the new board, so this is probably not the case with this chiller. Most likely problem with thermistor or EXV driver board if there is a problem at all. I have not seen enough info to lead me to believe there is a problem yet.

[double bubble]

You have to pay attention to the steps of the exv carrier makes two one is I think 600 and the other is about half that . this is hard cause I going from memory . I went down that road of replacing exv after getting wrong parts I finally got the right valve manufactured by mueller brass co. It's a crome dome and it fits perfect a little brasing needed . I hope I never run into that problem again because I didn't keep good notes on the part#'s ect. Also I would always change the driver board when exv is replaced .