Pump runs continually

[dick]

Hi I'm new to this forum,
I have a Myson Apollo boiler with 2 motorised valves for CH & HW with a honeywell controller. The problem is the system pump runs continually with hot water turned on at the controller even though water seems to be up to temperature and boiler not alight. The pump just seems to circulate the hot water going through the tank element .The pump turns off if hot water is selected off at the controller or the tank thermostat is turned down. If the boiler pump over-run thermostat was faulty then the pump would still run with the HW turned off, correct? The same problem does not occur with the central heating side of the system. Any ideas greatly appreciated

 

[Rodreguez]

Hi I'm new to this forum,
I have a Myson Apollo boiler with 2 motorised valves for CH & HW with a honeywell controller. The problem is the system pump runs continually with hot water turned on at the controller even though water seems to be up to temperature and boiler not alight. The pump just seems to circulate the hot water going through the tank element .The pump turns off if hot water is selected off at the controller or the tank thermostat is turned down. If the boiler pump over-run thermostat was faulty then the pump would still run with the HW turned off, correct? The same problem does not occur with the central heating side of the system. Any ideas greatly appreciated

Have you checked the hot water is up to temp. If it is the HW valve should shut the flow to the coil. Also check the thermostat is working correctly at set temp

 

[Mbear]

It sounds like the hw 2port valve is sticking on even when the hw temp is satisfied. If this valve sticks on it'll still give power to boiler&pump, the boiler won't operate all the time as it will cycle on and off as the boiler stat cuts in and out but the pump will just run and run if this is the fault is what. The fact that it doesn't do it on the ch selection rules out the pump overun possibilty for me.

Does that sound about right with regards to the symptoms I've explained etc

 

[dick]

Thanks for the prompt replies. I've had the lid of the HW motorised valve and it appears to be opening and closing when required and the microswitch isn't stuck in the closed position. Having said that, I exercised the tank thermostat last night and all appears ok this morning i.e a tank of hot water and the pump is not running. I'll keep an eye on it for a few days to see what happens.
Thanks again

 

[mrlennie]

I exercised the tank thermostat last night

Did it do its business?

 

[dick]

Not sure, I always turn my back. We all need a little privacy when doing these things

 

[mrlennie]

hehe I should really be doing something right about now...

 

[dick]

I'll turn my back then......

 

[mrlennie]

Hey!!! i didnt mean that hehe

 

[dick]

Quick update, system has been running correctly for the last two days. Problem solved, thanks for your help and suggestions, oh and humour!