Megaflo Mk5 water overheating / pump running

[Steverob]

I have a megaflo driven by an oil boiler, and there are several problems, maybe related. These are the symptoms:
a) the central heating is off, Danfoss zone valves upstairs and downstairs are closed, as expected.
b) the pump continues to run. This is such a common problem with my system that I always have a spare Danfoss zone valve so that I can change them out because of faulty microswitches. I don't think this is the case this time.
c) the water is super hot. Measured downstairs, the flow temperature from the tap is >75deg. I adjusted the megaflo thermostat like this, so I think the temperature should be 50deg C

So why is the pump continually running even when the heating is off (which seems to rule out the thermostat as the sole source of problems) , but does this explain the high water temperature? Or do I have two problems (microswitch and thermostat)? Could there be a microswitch issue in the water heating motorised valve (a Honeywell valve)?

Thanks for your suggestions.

 

[CountryFan]

You can’t assume they’re not broken. It’s likely a voltage is being sent somewhere, so needs to be tested.

 

[Steverob]

OK - I have taken the Honeywell valve off and found that microswitch was rammed closed and the motor was stuck. I took the motor out and found it to be sticky so have ordered another motor. That's certainly one fault found. Hopefully it's the only one.

 

[Steverob]

Looks like that was the issue: the motor had seized with the microswitch closed so the pump was continually running. I've replaced the motor and now it's behaving as it should: water temperature is now consistent with the thermostat setting. Thank you for the input!