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chillers paralleling

chillers paralleling

(OP)
dears,
at our project we have two carrier chillers (carrier model : 30GTN090) THEIR SET UP IS FOR BEING RUN IN PARALLEL, when we run them one chiller a time(single chiller) or two machines in parallel we get alarms(T051, T053 AND T055), I have tried the troubleshooting procedure (attached) from the machine manual, unfortunately couldn't find the reason behind that, your opinion about this problem will be highly appreciated .

RE: chillers paralleling

you have to check all the devices and measure pressures. high pressure indicates to little condenser flow. But the pressure switch could be faulty, or a relay...

RE: chillers paralleling

Are the condenser fans running? Looks like something is causing high head trip.

RE: chillers paralleling

Elec777 :is your chiller tripping after startup or is alarm persisting?

RE: chillers paralleling

Is this a new project or existing project, if it is an existing project, did you have this problem recently?

RE: chillers paralleling

(OP)
dears,
at our project we have two carrier chillers (carrier model : 30GTN090) THEIR SET UP IS FOR BEING RUN IN PARALLEL, when we run them one chiller a time(single chiller) or two machines in parallel we get alarms(T051, T053 AND T055), I have tried the troubleshooting procedure (attached) from the machine manual, unfortunately couldn't find the reason behind that, your opinion about this problem will be highly appreciated .
1- condenser fans running
2- as i understand from the troubleshooting schedule and what happens in reality, every alarm cod is associated with specific compressor(4 compressors in each chiller)so for example when alarm T051 show up on the screen the compressor No.1 will stop and the chiller continue running with compressors (1+2+3), the chiller stopped completely only when the 4 cods (51-52-53-54) show up on the screen, when we reset the alarms then the chiller will restart automatically.
3- since am new to the project, actually i have been informed that this problem is an old one and since the beginning 4 years back.

RE: chillers paralleling

so, have you checked in details all 6 possible reasons stated in the manual before asking help from others?

RE: chillers paralleling

What is the approach EWT and LWT sp? Was the water flow thru the chiller measured in a 1 and 2 unit run condition? My guess - going off on over load condition as determined in the CPCS. I saw this happen on 105 VAV carrier RTUs on low LAT and high OAT with LAT very low (52 F). My guess with all three compressors going off, you are taxing the condenser and calling for full load. Stage the loading to allow the condenser to follow the staging better. Are you letting the chiller stage or force from the BAS? Is the condenser clean? High water flow will aggravate this condition.

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