press or temp.?

[aaron crimmins]

we were having a discussion this morning in the shop about how all the guy like to control box temp. in walk ins and reach ins. either using pressure or return air temp. what do you guys like and why?

[bernie]

AAron, For walk in coolers(med temp) I prefer the use of the digital penn johnson controller. You can program the cut in and cut out temps, specify a specfic differential, and also a time guard. These stats utilize a electronic resistance silver bullet sensor and can be remotely mounted from the stat itself. These types also control frost very well on med temp coolers.
As far as freezers go it really dosent matter. They run 22 hrs a day, and defrost usually 4 times a day. I always stay away from
pressure type controllers as they are touchy setting up and take forever to confirm satisfactory control.