Servowarm 80 Elite pump running constantly

[dabaldie]

I have the above boiler. I know its ancient. 1985 i think...
I've replaced the circuitboard cos a relay was shot, anyway I've recently moved the divert valve to Hot Water only (no CH) and maybe i'm imagining it but the pump is constantly running.. even if you turn it off on the timer. Maybe it always did this. Is there any harm in it running like this? other than wasting a little electricity on the motor.
(maybe i'll move the diverter back and see what happens tonight.. but in the meantime any ideas?)

 

[doitall]

Pump comes on with the hot water or heating as it's fully pumped system, it then over-runs on shutdown for about 5mins

 

[kevplumb]

Pump comes on with the hot water or heating as it's fully pumped system, it then over-runs on shutdown for about 5mins

unless the overun stat is stuck

 

[dabaldie]

Thats what i thought it did.
i vaugely remember the pump running for a bit just after the CH went off.
but if i have the diverter on HW only and i'm not using any HW what is the pump doing other than moving water around the tank.
so i guess its knackered?

 

[dabaldie]

is there anyway i can test anything to find out if the 'overrun stat' is stuck?
the annoying thing is we hardly use any hot water except for 10 mins in the morn and 30 mins (bathing baby) in the eve.
if i move the diverter back to shared use and turn all the rads down to off.. will that waste energy (by keeping the water hot in the pipes)?

 

[doitall]

Could be several things that hold the pump on you can check the run on in the wiring box with a tester

 

[ChrisR]

Yes you're wasting electric in that the pump's running and gas in that the water's being cooled - unless you turn to CH only!

The stat or relay is knackd, which shouldn't be hard to find for an engr with a meter.

 

[dabaldie]

unless you turn to CH only!

in THIS weather!!!
i'm guessing it cant be the stat as the gas doesnt kick in to heat the water very often.
would the overrun timer be within the small circuitboard that i just replaced? (small metal silver box case). if so then i can get a new one under warranty. or is it somewhere else? (can only find one circuit board, the rest is wires, thermocouples(?) and the pump.