Trouble with a Dunham Bush Compressor

[bowhunter21]

I have a Dunham Bush chiller M#HRSC255DQ with 4 Hitatchi screw compressors. I am having a problem with one of the compressors. The compressor will sometimes load 100% and other times it will only load up @ 50-60% even though the load solenoid has 120volts and the leaving water temp keeps rising above setpoint. The compressor continues to operate unloaded with 148 degree suction bell temp, 4 degree superheat, and the discharge line temp keeps rising tripping the compressor on high oil temp. Anyone have any ideas?

[gregoryhiggs]

your metering device, is having problems.

[skwsproul]

Way to vague. More info will help greatly. Superheat, subcooling, water inlet and outlet temps, actual pressures not tranducer readings, amp draws versus rated and maybe more. I have had the displeasure of working on a few DB screw chillers and many here may be able to help.

BUT first you need to get your post count up to 15 then apply for a pro membership. Trust me it is worth your efforts to get the membership. You will find a huge amount of info available here but be forewarned this site is like crack once you get a taste your hooked.

[bowhunter21]

My superheat was 4 to 5 degrees, subcooling was 16 degrees, suction pressure was 63psi, discharge pressure was 217psi, inlet water temp was 54 degrees and leaving was 46(three compressors were on) and amperage was between 63 and 69 amps

[targetman]

Bowhunter21. Welcom to the site.

[skwsproul]

My superheat was 4 to 5 degrees, subcooling was 16 degrees, suction pressure was 63psi, discharge pressure was 217psi, inlet water temp was 54 degrees and leaving was 46(three compressors were on) and amperage was between 63 and 69 amps

Good info. Keep posting. Yes welcome to this site sounds like you will not have any trouble getting your pro status. DB's are fun huh. Where do you get parts for them there.

Does this chiller have the retarded display mounted on the door with a layer of circuit boards behind it and about 10 other cpu boards like AI/AO and DI/DO and com and so forth and so on.

I had a lot of fun with those one summer.

[242447]

Sounds like your slipper seal is leaking by, Manual load compressor to 100% and then put in hold if the percentage of load drops you slipper seal leaks and you need to replace pain in the ass to do how many hours are on the compressor you my want to replace compressor

[bowhunter21]

Do you know where I can get a manual for that compressor

[skwsproul]

Try this http://www.accscompressor.com/ it was listed on Hitachis web site.

[bowhunter21]

Thanks I will check it out

[snowy24aug]

Thanks for the link, i need the manual as well

[shea1]

Bowhunter, I have worked on these compressors. Call the manufacturer they're very helpful. There are two sizes and believe it or not they will refer to them as the big one or the little one. From my understanding their layout is close. There are tests you can run to determine if you problem is in the solenoids or the slide valve. From what you said it could be a few things, one make sure your charge is right. A low charge will raise your oil temp and also prevent you from loading the compressor fully. The other is a leaking unloading valve or leaking load valve. There should be three total. These can be checked by bypassing discharge gas into one of the ports on the side of the compressor through your manifold. A temperature change in your capillary tubes on the side of the compressor indicate a hung or leaking solenoid. If all prove well then your slide valve needs to be cleaned and the slipper ring needs to be replaced. The job isnt so bad, but I recommend buying two slipper rings in case you wreck the first one (theyre cheap) Instructions are very detailed from the manufacturer it isn't hard just tedious. Good luck

[bowhunter21]

Thanks for the info, it is very helpful. From what I have been hearing sounds like it is a bad slipper ring!

[shea1]

You dont want to replace the ring if you dont have to... from what I remember I would check the charge first. Usually a warm suction temp doesnt cool the compressor enough and allows the oil temp to peak... whats the setting BTW?

[supertek65]

I THINK THEY CALL IT A SLIPPER RING BECAUSE IT IS VERY EASY TO LET IT SLIP INTO THE COMPRESSOR AND YOU HAVE TO GET ANOTHER ONE LOL

AC COMPONENTS ARE VERY NICE PEOPLE AND WILL HELP YOU.

BE SURE YOU HAVE A COUPLE LONG STUDS WHEN YOU PULL THE SEPARATOR



ST65

[supertek65]

BY THE WAY!!!!

ONE TIME I GOOGLED HITACHI SCREW ANF FOUND HITACHI MAGIC WAND!!!

YOU CAN HAVE ALOT MORE FUN WITH THE HITACHI MAGIC WAND LOL



ST65