Supermarket Defrost Problem

[etterold]

I have a Hu**man R507 rack, controlled by a Em***son E2.The system in question is a Hu**man FWG operated with a sp**lan CDS9 epr. There are 6 evaporators all with CDS4 (Dual Temp Island). On this system there is two evaporators (one side) that are not getting enough defrost and ice up after a few days. No other systems (24 in total) on the rack are having problems, and this is not the farthest run only 120 ft el.DDR valve is operating at a 25# delta p.defrost time is 18min with a 1min drip (Hot gas).The E2 is showing the CDS4 open 100% on defrost with the main 0% Does anyone have any ideas as to what could be causing this problem?

[jpsmith1cm]

1 min drip? Sounds short for a low temp case.

A test I like to do on reverse gas defrosts like this is to measure liquid line temp leaving the case during defrost. Monitor liq temp from defrost beginning to end. It should start normal, drop off to 30ish, then rise up again. I will typically terminate defrost between 75 and 80 on an open case defrost and give it 5-8 minutes of runoff.

[etterold]

I agree 1 min drip is short, it came 1 min speq.I normally go with 5min. Trem is 75deg f the system always goes through full time.E2 states average temp during defrost is 35deg f. The two sections that are causing me trouble don't seem to be feeding all the time through the CDS during defrost, and I am new to CDS and unsure of the correct procedure of testing them. I guess I will call Sp**lan Monday and find out through them.

[crackertech]

I agree 1 min drip is short, it came 1 min speq.I normally go with 5min. Trem is 75deg f the system always goes through full time.E2 states average temp during defrost is 35deg f. The two sections that are causing me trouble don't seem to be feeding all the time through the CDS during defrost, and I am new to CDS and unsure of the correct procedure of testing them. I guess I will call Sp**lan Monday and find out through them.

Here's some info on CDS valves.http://sporlan.jandrewschoen.com/100-40.htm

[jpsmith1cm]

Sporlan does make a tool to force the valves open and closed.

About $250 from my United branch.

Did the system ever defrost or has it recently started malfunctioning?

If it has been a problem since jump, I would look to valve wiring or setup. EEPR valves have to be initialized on startup so that it knows where zero position is.

Stepper valves are pretty simple and trouble free.

If they have a good controller and enough power they will work fine. 12VDC.


#14 wire also on the longer runs.

[crackertech]

Sporlan does make a tool to force the valves open and closed.

About $250 from my United branch.

Did the system ever defrost or has it recently started malfunctioning?

If it has been a problem since jump, I would look to valve wiring or setup. EEPR valves have to be initialized on startup so that it knows where zero position is.

Stepper valves are pretty simple and trouble free.

If they have a good controller and enough power they will work fine. 12VDC.


#14 wire also on the longer runs.

That would the SMA-12 it takes 2 9volt batts and is a must have tool if your working with CDS valves.

[etterold]

That would the SMA-12 it takes 2 9volt batts and is a must have tool if your working with CDS valves.

Yes I have read the bulletin and I read about the SMA-12 so I will have to invest in one. (or make one)

[jpsmith1cm]

Please share plans if you make one.

I'm not putting my $$ into one and the boss says NO. For all of the problems I've had with them, it would not pay me to buy one.