Trane chiller HP Switch

[Kirky]

Hello all quick question, been called out to a aircooled Trane water chiller Model ECGAN900. One of the systems has repeatedly been tripping on HP. Have narrowed it down to a faulty HP switch and have now been given the go ahead to replace. At first glance switch looks like a dual HP/LP switch however on closer inspection it looks like a dual HP/HP switch as it is piped in from the high side in a single 1/4" pipe before teeing off into the switch. Any ideas why the system would need a dual HP switch I havent worked with one before and just want to make sure it isnt a design fault before I change the switch. All I can think off is that the switch is a two stage switch with the first stage limiting the system backing off the compressors and the second tripping the system on HP. But im only guessing.:rolleyes:

[WINJA]

hi ive seen a similar set up where one of the switches was called a "loss of charge switch" so the switches were in series and they were both normally closed and one opened on rise (hp) and one opened on fall (lp) and both were on the discharge

[FreezerGeezer]

Iirc, it's a dual hp switch. CGAN's use the LP transducer for a LP safety device.
I'll have to admit now that I don't know the PED well enough, but as I understand it if you fit a dual HP switch, you don't neccesarily need to fit a PRV. Several Trane (and I understand other manufacturers') chillers now have dual HP's and no PRV.

[Kirky]

Cheers for that. I think im going to go ahead and replace like for like. Strange though the system also has dual port PRV's on.

[Lowrider]

Following the PED a dual high pressure pressostat is enough to protect a 90 ton air cooled chiller. How ever, older laws can call for more than just that.

The machines are all manufactured in France (the E in ECGAN = Epinal) for Europe, Middle East and Africa. European and aspecially Dutch law called for different safety devices than say Africa. But to keep production cost to a minimum all machines come with a dual pressostat.

Might be worth you while to also chech the settings on the controller (CH532) and if installed, the yd of the first stage. Some of those Telemecanique relais just don't fuction the way they should!

Have a look at the settings for the fan control and the HP limit setting.


Cheers for that. I think im going to go ahead and replace like for like. Strange though the system also has dual port PRV's on.