Jackson Tempstar GP technical manual Overview of Operation

OVERVIEW OF OPERATION (CONTINUED)

The operator may turn the power off at the ON/OFF switch for approximately 5 seconds, and then back on. This will also reset the ECB and the DSI. If flame is lost during normal burn, the DSI will attempt a reignition.

The ECB monitors the 12vdc signal from the DSI to the combination gas cutoff valve. The software in the ECB also reads the temperature at the middle of the heat exchanger with the T-mid thermistor. After the 5.5 second ignition time, the software will increase gas flow to the burner to minimum burn by increasing voltage to the modulating valve (MV). If the heat exchanger temperature is far away from the stabilization temperature, the software will increase gas flow to maximum burn.

Once the heat exchanger temperature nears the stabilization temperature the gas flow is slowly reduced until the minimum burn is attained. The software will keep the unit in minimum burn until the heat exchanger temperature exceeds stabilization tempera- ture and then the gas will be shut off. Over many minutes, the software will turn the burner off and on repeatedly until all the water in the system reaches the stabilization temperature. At this point the software will only turn the burner on every 1-2 minutes to maintain the stabilization temperature. Now the unit is ready for operation.

As the dishwasher rinses with hot water from the booster tank, it is replaced with cooler water. The need to heat the new water is sensed by the software and the burner is turned on. The software will modulate the gas flow between minimum and maximum gas flow attempting to recover the stabilization temperature and always keeping the tank temperature above the required temperature.

The stabilization temperature may be adjusted by means of a potentiometer located on the ECB. This is referred to as the T- set. (normally 4.25vdc)

The recirculating pump draws water from the rinse booster tank and circulates it through the wash tank coils where it will heat the water residing in the wash tank. The water then returns to the heat exchanger where it is reheated. This hot water then flows back to the rinse booster tank and repeats the cycle.

The thermostat,(in conjunction with the wash temp relay) is used during idle times to prevent wash tank temperature from exceeding 170B F, during normal operation the wash tank will self regulate between 150-165B. However, when idle, the temperature in the wash tank will slowly rise towards booster tank temperature until the temperature reaches 170B F. The wash tank thermostat will cycle the heat exchanger & recirculating pump off. When the wash tank temperature lowers, the heat exchanger and recirculating pump will energize. This will continue during all idle time. At any time that the unit is placed into operation, the wash

temp relay will energize and immediately power the heat exchanger and the recirculating pump, regardless of the thermostats position.

Excessive high temperatures in the system are avoided by the following: 1. High temperature limit control by input from T-mid thermistor, 2. energy cutoff temperature lockout (ECO) by means of a bi-metallic switch independent of the microprocessor which will break voltage to the combination gas cutoff valve if temperature in the system exceeds 210 F.

Excessive high pressures that potentially could be created in the system are vented directly to atmosphere by means of the rinse booster tank and rinse arms.

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