Rev 8/2014
PrecisionTemp, Inc • 11 Sunnybrook Drive • Cincinnati, Ohio, 45237 • 1-800-934-9690 •
fax 513-641-0733 61
SB-20 Testing the PT-56
Model: PT-56
Other service documents required:
Thermistor Reading – T-mid/T-out
Tools Required:
Precision screwdriver
Gas supply pressure (to regulator) = 7.0 – 10.5 wci for natural gas (NG)
11.0 – 14.0 wci for propane (LPG)
Water supply pressure to booster = 25 psig normal (60 psig maximum)
Instrumentation:
T-mid Circuit board thermistor reading (yellow test connector)
T-out Circuit board thermistor reading (orange test connector)
T-set Circuit board thermistor reading (blue test connector)
Test Data :
1. Turn power ON and verify that the green LED flashes.
2. Is the red LED flashing? If yes, refer to Section 5 in trouble-shooting manual.
3. Verify unit lights off at ignition burn (0.19 – 0.35 wci) and ramps to maximum
burn (3.15 – 3.80 wci).
4. While the unit is heating to the stabilization temperature set the T-set as
described in the owner’s manual. Find the booster output temperature in the
table below and then go to the column that specifies the T-set voltage. Refer to
section 4.11 ‘Thermistor Checkout – T-mid/T-out’ for a description on how to
read T-set:
Outlet Temperature
Stabilization
Temperature
T_set Voltage, vdc
140 158 (1.27 vdc) 1.75
150 168 (1.10 vdc) 2.38
160 178 (0.95 vdc) 3.00
170 188 (0.82 vdc) 3.62
180 198 (0.71 vdc) 4.25
5. Verify that the burner modulates down as the stabilization temperature is
reached. The minimum burn is 0.90 – 1.50 wci).
6. Verify that the unit cycles ON and OFF at the stabilization temperature to
control and hold the temperature.
7. Let the unit reach stabilization. When burner is OFF and right before a re-light
read T-out voltage. Refer to Section 4.1 ‘Thermistor Checkout – T-mid/T-out’
for a description on how to read the thermistors. This should be within
±
±±
±0.02 vdc (±
±±
±2°
°°
°F) of the stabilization temperature listed in the table above.
8. Run several dishwasher cycles that the PT56 responds by igniting to maintain
temperature.
9. Fail T-mid thermistor by disconnecting the 2-pin connector. Verify that gas flow
is shutoff and the maintenance code is one on the red LED.
10. Verify that the unit does not leak water.
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