glow worm back boiler over heat?

[STU1965]

I have a glowworm back boiler, gas fire frontage all gravity fed,
the boiler has started knocking off when heating system has been switched on after reaching its temperature, the ignition light goes out and it seems to shut down, I assume there is an overtemp kicking in, why is it overheating? the boiler can be reignited straight away but it happens again.

stu.

 

[Agile]

Are you really quite sure that there is no pump ???

It has been normal to have pumped heating for the last 40 years!

Tony Glazier

 

[Nige F]

Are you really quite sure that there is no pump ???

It has been normal to have pumper heating for the last 40 years!

Tony Glazier

........................But do you remember how slow/weak the pumps were? I`ve got an old customer still running one,simply because a new kitchen was built in around it Well` they could`ve asked me SMC.

 

[STU1965]

you r correct, boiler is gravity fed for water and pumped to heating, pump is working, I have increased speed and it has made no difference, can problem be thermostat on boiler?

stu

 

[Agile]

Its all very well you telling me that "the pump is working". I would ask you to tell me how you know that?

Is there water in ALL the system? Again rather than saying "yes" can you tell me how you know it please?

Tony Glazier

 

[STU1965]

radiator system has been bled, floor boards were lifted and pump checked to see if it was running, i also increased speed of pump by turning the speed switch on side and heard a definite increase in revs, heating was checked and all rads became hot quickly, so i assume pump is working fine,

stu