Presented by Neal Thompson of KE2 Them Solutions, Inc. (http://www.ke2therm.com) and A.J. Saucier of KE2.
Topic of conversation is Intelligent Refrigeration System Control. This controller controls all system operation but also does a continuous diagnostic loop. Controls and communicates.
Key features include alarms for door open, high temps, superheat issues, and defrost issues. Control eliminates: defrost time clock, thermostat, and defrost termination control.
Temperature difference across evaporator in traditional system is about 10 degrees bellow box temp. Control turns off the fan when the temperature satisfies, this is a change from the traditional commercial method of leaving the fan running. leaves question on hot/cold spots in cooler? Sensors are located behind evaporator about 18″ from ceiling and 8-10 inches behind evaporator. Cut in and cut-out differential is close to 1 degree. The control keeps track of compressor run times and cycling to prevent short cycling and compressor damage. The shut down of the fans prevents product warming between cycles.
TEV Superheat – is known for not being able to keep up. In a normal system when an evaporator fan goes bad the superheat changes. The superheat changes based on operating conditions and sometimes even seasonal. The books say that superheat must be checked at design temperature. If superheat is set with space at 20 degrees it will be lower when the space is at run condition of 0 degrees. The reality is that the coil temperature is more important than room temperature when checking superheat. Anytime the design changes (changing set point from 0 degrees to -5 degrees) changes the superheat and superheat must be checked. Loosing evaporator fan, bad defrost and partially iced coils, all cause superheat change and you have a possible flooded compressor.
- Superheat changes with room temp
- Superheat changes with ice
- Superheat changes with faulty fan
- Superheat changes with dirty evaporator
When is the superheat correct with a TEV? never. It is either too high or dangerously low.
(Diagnostic chart from Garth Dennison)
ColdWar-March-2006-Ups-and-Downs-of-Servicing
If using an EEV the entire Superheat column of troubleshooting does not matter. EEV’s control adjusts and adapts to the ever changing conditions of superheat.
The control being discussed (and advertised) in this session is the KE2 Evaporator Efficiency Control. The technology is cloud based with multiple security/credential levels. There is a nice interactive demo here.
