Grant Vortex Eco stuck on

[MarkandCath]

I am an Electrician and I have just been called to a Grant Vortex Eco that will not turn off.

All the external controls are correct. The 2 control wires from the wiring centre to the boiler switch the 230v on and off when you request HW or CH. However, with both of them off the boiler still runs. I believe it is the CH that is stuck on because the radiators get hot. It is safe enough because it does turn off with the boiler thermostat when the rads are up to temperature.

My guess is a stuck control relay, I told her to call a heating engineer but no one will go out until the new year. Anyone any advice on the internal electrics of these particular boilers? Thanks.

 

[Exedon]

Which model combi? heat only?system? Internal? external?
Connections and wireing can be hugely different.
No frost stat hidden away?

 

[MarkandCath]

Internal wall hung and non system going on the pictures on the grant spares site. The control panel is a MPCBS108

I thought the frost stats wired into the wiring centre but if it is somewhere else then I will check it.

Thank you.

 

[Exedon]

Assuming it's a current model boiler electrical they are very simple no relays just a series of thermostats .
Don't use on/off switch on boiler they fail for fun!

 

[CBW]

So you’ve checked the motorised valve?

 

[MarkandCath]

So you’ve checked the motorised valve?

No idea how but if you could advise I am trying to help this old lady out.

 

[ianmcd]

No idea how but if you could advise I am trying to help this old lady out.

remove both orange wires at the wiring centre and see if the boiler now goes off, if it does, then check for continuity between the grey wires and each orange, which ever one shows continuity that is the faulty valve

 

[MarkandCath]

Thank you. I just got back from the customers and the CH valve is gone. I observed the HW valve moving the arm but the CH one was dead. I moved the arm by hand and it turned off the boiler but there was zero resistance so the motor is clearly shot.

Last question. It is a Drayton ZA5 valve and I can get a new one locally, can I just change the head or is life not that simple?

Thanks again for educating a sparky.

 

[CBW]

Should be able to swap the head, should be a black plastic tab on the side that pushes in to release the head.