Central Heating Water Pump will not switch off

[samuraijim]

The pump on my central heating system is on permanantly even when hot water and heating button are switched off. Only way to stop it is to cut the mains switch.

The system has not been touched, no new parts, no serivce or anything.

Where the pump is fitted there then follows one of these

http://www.toolstation.com/images/library/stock/webbig/60151.jpg

Does this have something to do with the problem.

Any help and guidance would be very much appreciated before I ring the plumber!

thanks

jim

 

[Biguns]

What boiler have you got ? Could be a duff pump overrun stat

 

[samuraijim]

BAXI SOLO 3 PFL 70

 

[Gasman28]

Microswitch sticking on your mid position valve ( the one in your picture )
Isolate the CH electrics and remove the outer casing. Inside, there are two screws that hold the powerhead to the valve. Remove the head and you'll find a spindle which should turn easily, but the travel isn't that far. Lubricate and free with a small adjustable spanner. Replace the powerhead, turn on and test. If it still doesn't work, then you will have to replace the powerhead.

 

[samuraijim]

Thank you for your response.

Just so that I'm crystal clear (not done anything like this before) is the mid position valve the device that says "drayton mid position actuator". What exactly is the microswitch? is that what i'm going to free-up? Also what should i lubricate with? will wd40 do or something else?

Thanks again. this is sooo helpful

 

[Gasman28]

Have a look here

http://www.rkm-heating-controls.co.uk/3port.shtml

WD40 is OK to lubricate the spindle, but do not try to turn it through 180/360 degrees, it only moves a fraction

 

[Biguns]

Your original post says the pump is running continuously,even when controls are off. Is it only the pump, or is it also the boiler ?

 

[stem]

Probably the boiler PCB I'm afraid, My Solo has also done this. The pump is controlled by the boiler PCB, so that it runs on for a while after the boiler goes off to prevent the overheat tripping.

Does the 'Boiler on' light on the thermostat housing go out when you switch off the heating and hot water? If so, the motorised valves are switching the boiler off, which is correct. If the pump continues running for more than 10 minutes after this light goes out, then the boiler PCB is not releasing the pump.

If on the other hand the 'Boiler on' light stays on when the heating and hot water are turned off, suspect the motorised valve.

 

[Biguns]

agree

 

[samuraijim]

Thank you - it's only the pump and not the boiler that stays on? What should be the next step? I'm not sure what advice I should be following. Thansk again everyone

 

[Biguns]

got an appointment with a landlord at 9pm
I would read Stem. good luck

 

[Homesafe]

It's the pump overrun stat. did one before christmas .

Mind you the mid position valve didn't fully work so it was also changed,

get someone to have a look at both for you.

 

[gaspro1981]

it will be the pcb common fault wiv the solo pf