3 port keeping the heating on?

[spikewt]

Long story short. Changed a 3 port which is now sending 80v to the boiler switch live once the heating is turned on then off, so it fires all the time. Works as it should on the hot water. Valve Mi says that's what it should be doin.
Is there a valve out there that cuts the voltage off completely.
It's on a poxy biasi boiler but then it's actually workin as it should.
Thanks for reading.

 

[Ermintrude]

You've got a short somewhere mate. Or a very cheap and nasty valve

 

[spikewt]

Had my sparky there for 3 hours. Changed everything for new stuff. Triple checked the wiring, tried 2 brand new and different valves. Still does the same thing. If you look at the honey well valve, it says there will always be between 50 and 150 volt coming out when there's no demand.
We just don't get it.
Problem is I changed the valve 2 months ago and haven't gotta clue what it was I took out.

 

[spikewt]

http://www.honeywelluk.com/documents/All/pdf/975.pdf

This is where iv read about the voltage staying there. Last paragraph.

 

[doitmyself]

The low voltage on the valve's orange wire is a 'feature' of all mid-position valves and boiler manufacturers are aware of this. If the boiler is being turned on by this voltage, then the problem is more likely to be in the boiler.

 

[bigads28]

It shouldn't fire on 80v, what's the model of your boiler?

 

[Ermintrude]

Fit a relay?

 

[spikewt]

It shouldn't fire on 80v, what's the model of your boiler?

Biasi M96.28 SR / C2

G.C. 41-583-02

Problem iv got is I serviced it 2 months ago, switched the heating on, then the original valve starting letting water through the heating side while on hot water in the summer. So i changed the valve as the ball was damaged and now this is happening.

 

[bigads28]

Remove the switched live and see if the fault remains.

The three led's on the left hand side might indicate what the boiler thinks it should be doing.

ON OFF ON is CH operation
ON ON OFF is frost

I can imagine yer loosing your hair fast with this one!

 

[spikewt]

Switch live was one of the things i tried. boiler shuts down as it should.

Its just so annoying because everything is working exactly as it should and has been checked over and over. Its just this 89v on the switch live from the orange wire on the valve and a cylinder stat wire that makes the boiler fire.

89v should be there, just not activate the boiler. Im reluctant to replace the pcb as ill be paying for it but by the sounds of it, its becoming the last choice.