Mc Quay Chiller Problems

[Robb]

I have a 160 ton water cooled McQuay chiller that is going off on low preesure freeze stat. It is a dual circuit with 4 Copeland compressors. The condenser and evap water flow is in spec. Only one circuit is acting up. I suspect the evaporator may be fouled The circuit that is bad is the first one on the evap water inlet. It is only running with a clear sightglass at 40 lb suction and a 150 lb head. I did check the liquid line pressure drop on both circuits. One is 25 and the other is 15 lbs. I am going to change the cores and then check the TXV superheat. It looks like the evap is not cleanable like the condenser is. Any one else have a similar problem?

[sedgy]

this sounds like a evaporator tube problem, it requires inspecting, and eather <brush< rod cleaning or chemicaly cleaned and have you inspected the chilled water strainer ?

[Robb]

It does not have an external strainer like lots do. Do you think it may be right at the shell inlet?

[sedgy]

anything is possible in your trade lol

[sedgy]

robb, where a large pipe goes onto the end of the evaporator the water starts to go through small pipes < usually< this is a restriction and so any contaminant < plastic bags < will clog up the ends of the pipes, is there no way of opening up the evap end?

[Robb]

I am going to remove the inlet and see what shape the piping is in. Looks like the only way to clean it is chemically.

[sedgy]

ok robb, take it easy + let us know how you go on with it
sedgy

[muju]

whenever u post, please mention type of compressor and chiller model no. Check the txv may be its closing as sight glass is clear, what r the water temp. Also check txv for blockage, check if sight full or empty, may be a refrigerant leak.