Lennox LCH 803 vk expansion valve fault

[ianros]

i have a lennox lch803 3 stage chiller with an expansion valve fault. when the plant goes into a start up procedure it pre heats the valves(danfoss tq 55) as normal then goes into valve fail. i have 0-10v from control panel driving the vop relay panel and a 24v feed pre- heating the valve. the sensor cable is also in tact and have been continuity tested. any ideas????

[Brian_UK]

Don't know those valves but had a Carel EEV show fail on me when the stepper motor was not moving the valve internals properly. On power up the valve was not positioned by the motor at the end of it's travel and the controller classed it as a fault.

My stepper motor had corroded around the valve stem and was not making good electrical/magnetic signal transfer.

I see from the Danfoss sites that your EEV has just run out of spares support, 5 years from 2006, perhaps it is time to consider replacement with a later model.

[ianros]

thanks for the reply, i have told the client ro replace one of the valves to start but i was bieng cautious as there is 90 kg of gas in each circuit and 3 circuits. all 3 are showing the same fault, but the maintenance bloke on site is always shy with the truth and i dont know how long the problem has been going on as he is known for just resetting faults.

[Grizzly]

Hi Ian.
Your issue is strange because it involves all 3 circuits?

I quote " Note:- If either sensor goes open or short circuit or goes out of range, the valve will force close."
These sensors read 1000 ohm @ 0 deg C



That's from old Danfoss info I have. I was wondering whether there had been a power spike to the chiller that you have not been told about?

Is the controller a EKS 65 by any chance?

Or is it the lennox Climatic (CL50)? In which case what fault code are you getting?

Good luck Grizzly