Delfield prep cooler

[jackal]

:confused:

I got a service call on a Delfield model: 18660PTB small prep cooler. This is the style (2 door) that keeps medium temperature products cool below and prep items up in a seperately cooled rail above. The unit has one compressor that is controlled by some combination of a pressure cut-in, cut-out control, an evaporator sensing thermostat for the lower products and a liquid line solenoid that can cut off refrigerant to the upper rail. The complaint is that the upper rail food item freeze overnight when the top is closed. There is no schematic so I'm not certain if I'm supposed to adjust the pressure control or what to get warmer temperatures in the rail. Mechanically all components seem to function properly.

I guess my questions are: does the pressure control operate the solenoid for the rail and the evaporator sensing thermostat below operate the lower part and both components are wired in parallel with the compressor?

The upper rail has a fair bit of frost in the evaporator. Is this normal? Or should it defrost in the off cycle or perhaps be defrosted by store employees?

I've worked on these style coolers before, but it was always a dirty condenser, fan motor or whatever.

Thanks in advance.

[mrfixit-76]

The pressure control is for the top rail and the t-stat is for the box. The compressor should be slaved to the same pressure control as the top rail. This will allow the bottom to maintain temp and actuate the compresoor and it will also limit the temp of the top rail. Good luck

[the mojo]

The T-Stat for the top rail is an option. There is a sensing well to the underside of the top rail. The pressure switch is used to maintain a design temp of 28*F. 10 T.D. for temporary food storage. Remove food during non-buisness hours or high moisture content food will freeze. The cold wall design is to conform to NSF-7 standards.

[yotaman16]

From the prep tables that i have worked on in the past the top plate area does have frost. There is usually an air defrost on these, which shuts the top down over nite...I dont recall on the delfields if there is a thermostat or not. I know there are 2 thermostats on the Kairak units.

[MikeySq]

I like Delfield stuff, don't work on too much of it though up here in Canada!

http://www.delfield.com/docs/uploaded/del/specsheets/DS18PTB.pdf

-Mike

[ezone]

Jackal these things always build ice. Customer is suppose to mt @ night and defrost. not for storage. Look for rail switch, shuts off rail for cleaning, and defrost. Hard part is explaning NSF 7 to end user. New temp requirements forced mfgs to get creative, static rails,baffles, holes in strange places,and my favorite one....what the hell is this little fan for???

[jackal]

Thanks all for the responses. I guess bottom line is don't store product in upper rail overnight or you will freeze items--frost is normal.:o

Thanks again.

[Jackson1]

Sounds similar to a victory v line pizza table. In that case alot of times the top cold rail satsfies when the lower cabnet satisfies. the temp control shuts down the solonoid which opens the low pressure control, shutting down the compressor. Long story short, if you use deep pans 6" instead of 4" you will freeze the product. The cold rail may be rated to for a 4 hour holding period. Over night storage may not be an option in the cold rail. Check with the manufacturer. You might double check to see which branch the solonoid is shutting down.

[R12rules]

Jackal these things always build ice. Customer is suppose to mt @ night and defrost. not for storage. Look for rail switch, shuts off rail for cleaning, and defrost. Hard part is explaning NSF 7 to end user. New temp requirements forced mfgs to get creative, static rails,baffles, holes in strange places,and my favorite one....what the hell is this little fan for???

yep... top is NOT for overnight storage! Plain and simple