Trane control issues perhaps?

Hi guys

Have an old air cooled Trane chiller ECGCH250 that's had a retro fit and XP40 fridge used.

We had an issue when carrying out the HP trip as it wasn't operating correctly and fault 'Mckt2' came up relating to 'pressostat fault'

We installed a new dual HP LP switch and used OFN to check that the trip operates as it should, which it did, so thought happy days.

Whilst this was operating chiller didn't throw up the above fault and was recharged.

Charged up and then the chiller decides to throw the fault up again.

At a loss, any ideas?

Controls issue?
Blocked capillary line?


Many thanks

Just to add to this, linking out the dual switch removes the fault but worked fine before it was installed.

Been looking at literature and it states that there should be no sharp bends etc within at least 4" before for flare nut connection into the switch.

So would oil cause an issue and no let the switch reset possibly?

Attachment 15054

The old switch is the second one up so I'm wondering if the oil is not draining away properly

R449a seems an odd choice for a liquid chiller, what was the original refrigerant?

What is the pressure switch set to and what is the pressure that the switch trips at?

The original was 407c I believe.

Trio was set to 20Bar as prvs are rated at 27.5 so wanted to make sure they didn’t lift.

I find it odd that on the ofn the switch tripped well several times. Then hooking it up to circuit it fails to reset. I’m wondering if oil is not draining out and thus clogging the internals?

I would think that a blocked capillary to the pressure switch is unlikely.

Have you monitored the pressures to find out which is activating the trip, also does the pressure change after the compressor has stopped? We're working in the dark here.

Umm the trip hasn’t activated at all when connected to the circuit. It went into the fault above relating to ‘pressostat’ we then linked out the hp switch and fault disappeared. It’s strange that it’s happned to two hp switches now. I’ll do a little more investigation on it as it seems a long shot

Double/triple check your switch wiring.

Hi Guys.
Just to throw a complete curve ball!
in the old SMM control Manual I have.
Mckt2 is listed as Hp OR Lp fault - reset HP Switch???
So check out whether the LP switch is in circuit too.

Good luck Grizzly

Thanks Brian

Grizzly, see attached old wiring diagram of said unit.

Common feeds HP switch, then the switch line of that feeds the LP switch which livens up the 2B20 2 and 3, then the chiller will run.

We are on J2 line 22 at the bottom.

Attachment 15055

Now I have changed the switch for a dual and this is the wiring diagram for new unit, so what would you say?

Attachment 15056

Many thanks gents

Hi Stretch.
It is difficult for my tired old eyes to make out the details on your drawing.
As best as I can Decipher it.
I would feed X1 in on 1 and out on the common to Junc. 3.
Basically then if the hp or lp drop out, you should be able to confirm by resting which has the issue!
Worth a try at least.
Anyone suggest different, please feel free to suggest other options.


Grizzly

Thanks grizzly

I fed common to 1 as instructed by manual, then 2 and 3 being lp and hp. When livened on 1, 2 then becomes live. This line I have taken to x10 that feeds the contractors for the compressors.

Then I’m stuck with the hp cable as I have no where to place it

Hi Stretch.
Sorry I was not clear enough.
x1 to 1 an 4 (Common) out to term 3 on the Input. (A1-1)
I read the other lamp terminals as Fault lamp / Alarm signal circuits.
1F2Q-4 is I think the Comp Thermal cut out and could be having a part to play in all this?
That could be your issue all along?
Hopefully you have a legend to clarify this?

I am struggling to clearly read the drawing.
However the switches are all in series so substituting the lp and Hp should be relatively simple.
good luck Grizzly

Yeah the drawing doesn’t come up big on here for some reason I’ll inbox you if ok just for clarification.

Yes X1 supplies the original hp switch which hen feeds the lp switch these need to be closed to enable the comps which are 2B 20 connected into X10.

The only thing I fail to see is if the 4 goes to the X10 to enable when there is a fault on the Hp or Lp where they signs to disable the circuit or am I looking into it too I’m depth? I’ve a 3 core and earth cable to the dual switch

Thanks

Ok think its dropped lol

I'll put the common X1 to 1 on the new dual switch, the 4 will then go to the X10 which livens up the compressor motor thermostat then enables the chiller to run.

So then I'm left with the 2 and 3 which I'm assuming are switch lines to potential alarms.

When the hp or lp trip this will move 1 over to 2/3

You Got it!
Grizzly

Well turned out to be a dodgy switch and had to replace it with another unit lol

Thanks all

Thanks for the update.