YCAV

[chill bill]

Hi Everyone,
Wondering what is the best way to test the feed / drain valves on the flash tank. Have a chiller, circuit 2 only, running for 5 mins or so then failing on low discharge superheat. The valves are the upgraded ones, but still think they are faulty. While circuit was running, pulled the plug on drain valve, expecting valve to shut off and start filling up the flash tank, but if anything, it slowly dropped. Tried this same test on circuit one which is running fine and tank did fill up. Have had level come up to sight glass around the 35-40% mark. Level sensor seems o.k. Refrigerant charge is o.k. Recently removed by another tech to replace damaged sensor. Refrigerant weighed back in. Suction superheat is also running a little high. Is there any info out there on testing the valves. Thanks.

[DFZ]

when you unplug the valves the stay in the position they are in at the time of unplug, they do not auto close with cable disconnected.

[chad_nc]

Is the economizer open when it trips on low discharge superheat? I have still seen the new valves fail. Set the suction superheat to 12 degrees and close the economizer valve and see if it still does it. If you can take a printout of the machine history and post it, could probably help you out a little more.

Good Luck

[chill bill]

Hi guys, had a thought that was the case when the plug was pulled during operation.
The economiser is still closed when it fails on low discharge superheat.

[chad_nc]

Put the chiller in service mode, drive the drain valve closed, unplug the drain valve, and start the circuit. If it starts pumping down its probably not the drain valve. Check sensors (mounting location, good contact, etc.). If the machine does not start pumping down the plunger on your drain valve has probably unscrewed its self, you can take a big wrench and pull the drain valve motor out and screw the plunger back on. (Isolate or reclaim the gas first obviously). If the motor on the valve is bad when you drive it open and closed in service mode it will not make the clicking noise when it hits the bottom and top of stroke, and if it is shorted it usually makes all of the other drain and feed valves on the machine act funny when the machine is sitting idle.

Good Luck

[22nomo]

Check the solenoid valve for the economizer, I had one that was leaking and kept giving me low discharge superheat alarms. You can close the ball valve in line with it to verify.

[chill bill]

ok, thanks for the tips guys. Will investigate further when back on site. Cheers.

[yorkman_gr]

to my opinion your problem with low discharge temperature is the suction temperature sensor, just keep in mind that your superheat is controlled by this sensor, and this sensor is controlling the drain valve, so if the sensor is out of range will keep the drain valve longer open and the result of it is low discharge temperature due liquid returning to the compressor, just check your sensor, and like the previous guys said, you don't have to disconnect your plugs from the danfoss controller, just go to the service mode add the code and then go to analog outputs and check your valves, 100% open should just less then 10vdc