START-UP PROCEDURES / SERVICING
GAS SHUT OFF | INLET VALVE | OUTLET VALVE |
VALVE | SOLENOID | SOLENOID |
MOUNTING
BRACKET
INLET PRESSURE TAP | OUTLET PRESSURE TAP |
| THROTTLE ADJUSTMENT |
Fig. 6-1 | OFFSET ADJUSTMENT |
PART 7. SERVICING
A.SEQUENCE OF OPERATION
1.When power is first applied to the control, the control display will read the outlet tempera- ture. The control will initially run through a self-diagnostic routine and then go into its oper- ating mode. If there is no call for heat, the System will go into an idle state.
2.If the thermostat is calling for heat, the control will apply power to the circulator pump. If the control determines the water temperature is below the programmed set point value minus the switching differential, the control will initiate a heating cycle.
3.The control then performs selected system diagnostic checks. If all checks are successfully passed, a pre-purge cycle is initiated (the blower will be on maximum speed).
4.When the pre-purge period is complete, power is applied to the spark ignitor for approxi- mately 6 seconds. Approximately 2 seconds later, we verify flame. If a flame is not verified during the trial-for-ignition, the gas valve is immediately closed and the control will return to step. After three trials, if a flame is not verified, the control will go into a lockout mode. If a flame is confirmed, the control enters the heating mode. The fire rate will be based on the proprietary algorithm.
5.When water temperature reaches the temperature set point value plus 10 degrees F (or if the thermostat call-for-heat is satisfied), the gas valve is closed and the control enters a post- purge state (the blower will be on maximum speed). NOTE: If the thermostat is still calling for heat, the circulator pump will continue to run until the thermostat call for heat is satis- fied.
6.When the post-purge is complete, the control enters an idle state while continuing to moni- tor temperature and the state of other system devices. If a call-for-heat is received, the con- trol will automatically return to step 2 in sequence and repeat the entire operating cycle.
During the idle state and heat state, if the control detects an improper operating state from external devices, such as the high-limit switch, the red light on the control will illuminate an error code will appear in the display.
B. MUNCHKIN TEMPORARY FAULT CONDITION
A Temporary Fault Condition may occur in the installation of the Munchkin. This condition may lead to a lock out condition of the controller, which will need to be manually reset through the S4/Reset button. These temporary codes will help the installer correct the problem before going into a lock out condition, which will require a manual reset. Example: A temporary fault-code of E15 indicates that the Air Pressure Switch is open when the fan is in the pre-purge function, when it should be
