Bad Batch

[chemuss]

Currently working on 6 copeland rack systems that are 3 yrs old, 18 compressors total, all the sump
heaters have open circuited. Any thoughts as to how this could happen? Heaters are in compressor m/n D6SJ1
400xAWMD sump htrs are 200watts.

[Magoo]

Perhaps overheating during compressor operation and not cycled off when compressor is running. Check heater supplies, should be through N/C auxilary at contactor.

[aramis]

Invite the previous crew for a beer, tell some tail about miss-wiring! :o

[chemuss]

Thanks for the reply, I checked sump temperatures and they are running
around 35 degrees whilst running and wiring is through n.c auxilary contacts. Thinking that compressors off cycle is too long causing them to over heat in compressor off cycle? Each rack is a bit over sized for application and a couple of the racks do not have unloaders on duty compressors. Thinking of replacing them and installing time clocks on each one and letting them run on for 15 minutes and then off for 15 minutes while compressors are in their off cycle to stop them getting too hot. Just a thought.

[chemuss]

Thanks for the info, all checks out ok, thinking off cycle of compressor is too long causing them to over heat. Will put new heaters in with time clock in circuit to run them on and off in 15 minute increments.

[Magoo]

Hi
sump temps at +35 'C while running is too cool, possibly below condensing in OZ. [Should be at least 5 degrees above SDT., absolute minimum]. This would cause foaming in sumps and other issues. Seems strange that all sump htrs failed. Double check all wiring and not connected as 400 vac, they would not last long. Overheat fizz bang broken. When fitting replacements check current draw and voltages at actual htr terminals on the first change out.