Worcester Greenstar 24RI Condenser Boiler

[BigglesTAP]

very intermittent. Flow valve was replaced not so long ago, the boiler i'snt that old, new programmer unit.
It seems to occasionally just stay on with the radiators staying constantly hot and not controlled by the house TStat.
It did it the other day.
The boiler is in the garage so has a separate frost stat.
Both HW and CH lights on the programmer were off. Tested the frost stat and had to turn it way up to click. We had a colder night say 8c so no reason it would have triggered.
The HW and CH should have turned off from the programmer but radiators still hot and hour or more after and boiler was firing up.
No control with the inside house stat.
Boiler reset then off and on did not fix it.
I have a mains switch next to the programmer which when switched off and on fixes it and then I probably wont see the problem for months.
Been going on for a few years now.

Read more: https://www.diynot.com/diy/threads/worcester-bosch-240-wont-switch-off.205147/#ixzz5UfOePWWh

 

[picasso]

Worcester ri boilers have a problem wlth Honeywell 3 port valves, the backfeed from the electronics in the valve head can bring the boiler on, there is a wb capacitor that goes across the switched live and neutral to stop it.

 

[BigglesTAP]

Many thx picasso,
this is the first time I've actually had a sensible reply on this issue.
Just had a look and the valve is a Drayton.
Is the issue the same?
Pix attached.
Do you know where I can find more information regarding this i.e. capacitor value etc.

 

[picasso]

Afaik draytons don't cause the same fault as Honeywell 3 ports.

 

[BigglesTAP]

Its model is MA1 not clear in the picture.
Hmmm so back to square one on this fault then?

 

[picasso]

Might be worth checking to see if you have any voltage on the orange when the valve is in different states .

 

[ollski]

The Draytons can send the same 70ish volts back which is enough to turn the boiler on. On the newer ri's the surpressor is built into the pcb, Worcester tech should be able to tell you from the serial number. I have occasionally had the Drayton valves induce 240v from the hw off to the orange calling connection in the actuator when they get hot.