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PRIMARY CONTROL FUNCTION - SAFETY LOCKOUT
CAUTION: DO NOT PUSH THE RESET BUTTON IF THE BURNER FLAME FAILS
AND THE FURNACE CHAMBER IS HOT! FORCING A REFIRE TOO SOON MAY PUT
FUEL INTO THE HOT COMBUSTION CHAMBER AND CAUSE AN EXPLOSION
HAZARD. SOME CONTROLS HAVE A AUTOMATIC RETRY FOR IGNITION AFTER
45 SECONDS. BEWARE THAT THIS CAN HAPPEN. DISCONNECT ALL POWER
BEFORE SERVICING OR THE BURNER COULD ATTEMPT A REFIRE AT A
UNWELCOME TIME. A SHOCK OR BURN HAZARD COULD OCCUR.
When the primary control locks out there is a malfunction. Determine the cause. The primary
control is a safety device similar to a breaker in an electrical circuit. It will lock out when:
1. The cad cell (electronic eye) detects a reduced, dirty, or no flame for many seconds. A
signal measured in ohms is communicated between the cad cell and the primary control.
A poor or absent flame produces a high ohm reading. When this signal is > 1500 ohms
the control may go into reset. A signal indicating a very good flame is < 500 ohms.
A moderate flame would be 500 to 1000 ohms.
2. The cad cell has failed, lens is dirty, or retention head is dirty.
3. The retention head fins are not allowing light to pass to the cad cell.
4. The cad cell receptacle is not making good contact with the cell eye.
5. The primary control is defective allowing the reset button to pop too easily.
6. The control is located in a high ambient temperature like a furnace mounted in a alcove
or small room that is retaining heat.
7. Once the chamber has cooled the control can be reset by depressing the red button for 5
seconds and releasing. Ignition will be attempted immediately if the wall thermostat
is looking for heat.
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