Set Appliance State:
Set Multimeter to Resistance 
Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
Disconnect primary flow switch at its inline connector
Primary flow switch is located in the flow from the gas to water heat exchanger
Disconnect primary flow switch at its inline connector
Primary flow switch is located in the flow from the gas to water heat exchanger
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Reset lock out as necessary.
Allow pump to run.
Measure resistance across the connections of the disconnected
flying lead that runs to the primary flow switch.
Note:
Expected resistance short circuit/zero resistance showing switch has operated,
allowance on zero resistance should be made if fused probe leads are used.
Allow pump to run.
Measure resistance across the connections of the disconnected
flying lead that runs to the primary flow switch.
Note:
Expected resistance short circuit/zero resistance showing switch has operated,
allowance on zero resistance should be made if fused probe leads are used.
Isolate as per TOPs P4
and refit as necessary