digistat and rf 601 stat appear to be working but the boiler will only supply hot water the motorised valve is not switching over.Tried new valve but still no joy can anyone help

john wanless, May 2012

It's the classic SCR fault:
Green light comes on, no heating, however your hot water is fine.

You need to replace the capacitor in ur SCR

if you search for "Drayton SCR part" on eBay, you will find me, I am the eBay seller 'bearsy72' , for just a few quid I can send you the part you need and full installation instructions / pictures, should only take 15mins to change.

You will need a soldering iron to complete the fix, if you don’t have one then send the SCR to me and I can change it for you for just a few extra quid, still way way cheaper than shelling out for a new system.

email me at
bach.dai1970 (at) gmail.com

I had to go to eBay as it is easier to keep track of the shipping, feel free to email me direct using the above if you prefer not to use the auction site

Thanks and hope to keep you all warm

Dave Cardiff, November 2012

worcester greenstar ?? Ri
GCN 41-311-??
DHW OK
NO CH?
look at installation manual page 8
which of the systems listed best describes your installation?
S plan?
Y plan?
fully pumped sealed system?
what programmer/timer do you have?
[honeywell danfoss drayton etc NEED MODEL NUMBER]
is the timer, wiring centre, fused spur & motorized valve all located in the same convenient location [eg airing cupboard]
i need the above information before we can proceed
but as a quick fix i would first try switching power off then back on from fused spur
& select CH on constant & roomstat on max
try to listen to the sound of relays clicking in timer & digistat reciever unit

manwithnoname, May 2012

It is a Worcester greenstar ri 3 years old

john wanless, May 2012

what make/model boiler do you have?
Look at the terminal strip on boiler
does ''switch live'' have power when heating on?
NO faulty digistat receiver unit
YES fault inside boiler (pcb relay?)

manwithnoname, May 2012