View Full Version : MTA 090 chiller

20-03-2017, 01:32 PM
Hi All,
Apologies if this is posted in the wrong forum..

Been working to commission a new MTA chiller and keep getting the water pressure switch fault.
The pressure switch is working fine, because when I turn on the external pump the switch is making and the relay for the switch is energised. When the pump is turned off the switch breaks and the relay de-energises.

Basically what is happening is, when the chiller is switch on, the fault appears on the screen. As soon as I reset the fault, I loose the 24 volt power supply from the output of the transformer that sends the 24 volt signal through the water pressure switch and on to the relay to 'tell' the chiller that the switch is made and flow is available. When the 24 Volt goes to 0 volt, the relay de-energises and the chiller tries to start.

But because the relay is de-energised, the chiller trips on the water pressure switch alarm, and at that point, the 24 volt comes back on and the relay energises again.

Been doing a lot of head scratching so wondered if you guys had ever come across this before?
Any help would be greatly appreciated.

20-03-2017, 02:47 PM
Will you have a problem bypassing the water switch?
Is it that important?

Is it a flow switch?

23-03-2017, 08:44 PM
Yes, same issue with looping out the flow switch. Its just a PD switch.
As soon as I hit reset, I loose the 24 volt signal from the transformer down through the connector block, through the flow switch and knows out the relay. The chiller tries to start as I have just resent the alarm.

But then it 'sees' the flow switch relay out, (due to the lose of the 24V) and trips on the alarm.
As soon as it trips, the 24V comes back on.

23-03-2017, 09:57 PM
Is it wired correctly?
Sounds like the NO/NC may be the wrong way round

23-03-2017, 10:05 PM
I am 100% with Frank.
Swap from what I assume is a connection on the NC to NO and see what happens.
Can you check the chiller model only 095 is not enough to be able to identify the chiller.
A model would be good.
Thanks Grizzly