I have an old Myson Economist boiler which although 28 years old and no doubt not very efficient generally works well. However after a pilot light failure I have reached a confusing situation.
The pilot thermocouple has a couple of spade connectors half way along it's length. Connected to these are 2 wires coming from a limit thermostat attached to the flow pipe above the heat exchanger.
I suspected the thermocouple had simply failed but when I bridged the 2 spade connectors with a wire link the pilot lit and remained lit. When I plugged the two thermostat wires back on the pilot again would not remain lit.
I put the continuity tester on across the two connections and with nothing attached the connectors on the thermocouple link showed a closed circuit. When I connected the tester across the wires to the limit thermostat they also showed a closed circuit.
The pilot will only remain lit if I bridge the two thermocouple connectors which is simply bridging an already closed circuit?
Why is this. I could understand it if it was showing an open circuit across the 2 connectors and the bridging wire was closing them.
What do I need to fix the situation and restore the thermal limiter arrangement.
The pilot thermocouple has a couple of spade connectors half way along it's length. Connected to these are 2 wires coming from a limit thermostat attached to the flow pipe above the heat exchanger.
I suspected the thermocouple had simply failed but when I bridged the 2 spade connectors with a wire link the pilot lit and remained lit. When I plugged the two thermostat wires back on the pilot again would not remain lit.
I put the continuity tester on across the two connections and with nothing attached the connectors on the thermocouple link showed a closed circuit. When I connected the tester across the wires to the limit thermostat they also showed a closed circuit.
The pilot will only remain lit if I bridge the two thermocouple connectors which is simply bridging an already closed circuit?
Why is this. I could understand it if it was showing an open circuit across the 2 connectors and the bridging wire was closing them.
What do I need to fix the situation and restore the thermal limiter arrangement.