Rev 8/2014
PrecisionTemp, Inc • 11 Sunnybrook Drive • Cincinnati, Ohio, 45237 • 1-800-934-9690 •
fax 513-641-0733 22
56 Gas Booster Heater Sequence of Operation
The PT-56 is an unvented gas booster heater designed to supply 180° final rinse water
to a single rack door warewasher. The sequence of operation is as follows:
• Power is on, the power switch glows and the green LED flashes. The
re-circulating pump draws cooler water from the bottom of the stainless tank
and pumps it through the copper heat exchanger.
• The water from the copper heat exchanger returns to the stainless tank via the
tee fitting in the top of the stainless tank.
Note: The next 5 steps take place in 3-5 seconds.
• If the T-mid thermistor
senses the water temperature is below set temperature, it
sends a signal to the green control board.
• The green control board, which is powered by the 12 VDC converter, sends
12 VDC through the black wire to the spark ignition module.
• The Ignition module simultaneously effects a spark through the heavy yellow
wire to the spark ignition probe over the burner and sends 12 VDC to the
combination gas valve via the blue and white wire. (Up to three ignition
attempts lasting up to 5.5 seconds max each).
• Ignition of the burner’s center element is effected and the flame is proofed and
monitored through the same yellow wire to the ignition module.
• The green control board sends 12 VDC via the back & white wire to the
modulating gas valve for one second to effect flame cross-over.
• The micro-processor on the green control board monitors water temperature
with the T-mid thermistor twice / second and varies voltage 0 –12 VDC to the
gas modulating valve in order to maintain constant temperature output.
• As the water in the stainless tank approaches set temperature, the gas flow is
cut back by the modulating gas valve by reducing the DC voltage to the valve
down to 0 volts. This is by-pass (low) gas flow.
• Burner remains lit until set temperature of the circulating water is reached. This
is sensed by the T-mid thermistor
and the burner is shut off. Note: If the flame is
extinguished for any reason, the combination gas valve will shut off is less than
1 second and re-ignition will be attempted.
• When the rinse solenoid of the warewasher opens, rinse water flows from the tee
fitting in the top of the stainless tank through the fitting on the bottom of the
heater to the warewasher. Cooler make-up water enters through the bottom tank
fitting.
• Burner will cycle on and off as the warewasher draws hot rinse water from the
stainless tank.
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