Worcester Greenstar 15Ri won't turn off!

[Ryanwaters48]

Hello all,

I'm just after a bit of advice... I have an intermittent problem with my 4 year old Worcester Greenstar 15Ri boiler. Sometimes, even when the thermostat is up to temperature, and the time controller clicks off, the boiler will carry on firing. When this happens, the water cylinder is way hotter than it should be, and the rads are burning hot. The only thing that stops it is turning the isolator off and on.

I came back after a weekend away to find the house at a toasty 27 degrees! Any ideas?

Ryan.

 

[AssuredHeating]

It's probably a problem with the diverter valve/valves in your airing cupboard rather than the boiler.

 

[Ermintrude]

I second the external controls

 

[GasmanxxxR1]

thirded, if thats even a word. Probs actuator on 3 port sticking

 

[Ledminer]

I have just joined the forum as I have a similar problem to Ryanswaters48 with an 18Ri. I have noticed that when the trouble occurs the 3 way is in the mid position. Usually I clear the problem by resetting the boiler and/or electrically isolating the system. The 3 way returns to W. I await next incident to see if the valve is stuck. Presumably new valve required to avoid the prob?
However, I have studied the circuit wiring and cannot see how the valve can hold the boiler on. To be on the programmer and either room or HW thermostat must request? Can anyone explain?

 

[ShaunCorbs]

micro-switches and replace the valve if older than 5 years / or suck

 

[Dotty]

Job 38.11.