Water cooled chiller with low pressure regarding electronic expansion shut down...!

[coolmanbhn@hotm]

Hi, Bjarne fromNorway here.

I’m facingbig problems with a 210 kW water cooled chiller…

Runningconditioning = cold side +5/0°C varm side 45/40°C. This unit have 2 circuitswith a total of 4 compressors 2 on each circuit. Circuit capacity on eachcircuit 50/50% or 110kW on each. We face a total of approx 3-4 weeks normalrunning conditions with no problems….suddenly we get low pressure problems withcircuit 1. This unit uses Carel electronic expansions valves type E3V-65 withEVD evolution twin driver.

When we getthis low pressure stop the technical personnel on site do not manage to resetbecause pressure side on this circuit is too low to restart. When we try torestart the compressor 1 starts up immediately and timer for compressor 2 countapproc 20 seconds then also this compressor start up. First we set theelectronic expansions valves with a 50 % preopening for 6 seconds under starup, but this was too short time so we had to set the default parameter onstandby mode to 25% opening to get the system the opportunity to pressure outwhen in standby mode.

After startup the circuit 1 runs perfectly. After approx. 30 minutes normal runtime weface 60% valve opening for circuit 1… opening for circuit 2 is only approx.30%? This unit has similar heat exchangers warm and cold side and equaltemperatures and pressures on high pressure side and low pressure side. Waterflow inlet warm and cold side is same pipe and therefore should be the same? Inlethigh temp side is still always more than 20°C and after 1 week of logging oftemperatures we do not get any answer regarding our low pressure problems/alarms.

Therfore…anybodyhad the same problem with this type of electronic expansions valves from Carel! That they just shut down without any known reason?

The reasonI did not change compressor start up delay between compressor 1 and 2 isbecause regulator Carel PCO3 with control panel do not have this option onchiller software at this moment…. We shall change out software as soon as weget it from the “Italian manufacture with brand name as should not bementioned” J

[nike123]

Did you checked sensors for superheat measurement that they are of correct resistance/voltage for sensed temperature?

[Gary]

What are the water temperatures entering and leaving the evaporator?

What are the water temperatures entering and leaving the condenser?

[nike123]

What are the water temperatures entering and leaving the evaporator?

What are the water temperatures entering and leaving the condenser?

I suppose this:

Runningconditioning = cold side +5/0°C varm side 45/40°C.

[Gary]

I would suppose the same, but confirmation would be good.