The infamous Ravenheat Combis.

[Godluvsatryer]

Ravenheat RSF820/20T Problems.
Hi everyone,
I have recently changed the diverter valve on the above boiler due to probs with the Hot water and all has been well for 8weeks.
Now the heating is not acting as it should. The heating is only staying on for about 10mins, the Rads. are getting hot and then the boiler is cutting out. The hot water is still hunky dory, Suggestions welcomed. Cheers

 

[chrishutt]

the Rads. are getting hot and then the boiler is cutting out

Sounds normal to me. What's the problem?

 

[Godluvsatryer]

I mean it is not firing back up again to keep at a constant temperature like it should be. It is going off and the Rads are going cold again.

 

[chrishutt]

So what do you have to do to get the boiler going again, or does it start by itself after a while?

 

[Godluvsatryer]

I just press the manual pad on the timer/program clock and it will fire up again for couple of mins and then shut down again. The boiler neon light and pilot is staying on throughout this.
I'm not sure if this will have any justification for saying, but the pipe from the boiler that goes to the rad system is getting so hot that you can barely touch it, even when the thermostat is on it lowest dial point! But it is still pumping to the rads initially.

 

[chrishutt]

Sounds like the flow through the CH side is very restricted. This would explain behaviour of boiler. Any ideas what might be restricting flow - sludge, air? Are you sure diverter valve is operating correctly in CH mode?

 

[andsam]

Faulty ch thermisters are common on this model.

 

[Godluvsatryer]

Thanks for the feedback so far!!
Here's the plan, On Saturday I shall turn the water supply off and drain the system, while I am at it I shall flush the Rads through to eliminate sludge, reconnect bleed it all and whilst rubbing a rabbit foot and clutching a four leaf clover, fire it up and pray to God, Allah or whoever will listen*
As a back up I have located a C.H. thermostsat ready in case Plan A does not work.
Will post on Sunday with any news. Cheers again.

 

[Godluvsatryer]

Hi again everyone, The saga continues,
I drained, flushed refilled and bled. Still no joy, BUT: I noticed that the digital programable clock on the boiler is actually losing power and going on and off all on its own.
When the digital clock goes off and decides to come back on it is either in the ON, AUTO or OFF display position.
This I believe is cutting the heating out. Could I be right or is it the other way round?
The boiler is still on and lit throughout all this.
Could it be a microswitch linked to the diverter valve,that in hindsight I should off changed when I replaced the diverter valve?

 

[Agile]

You could always bypass the switching contacts on the digital timeclock.

That is if you are able to do it safely!

Tony Glazier

 

[Godluvsatryer]

Thanks alot everyone for all the advice. I have ordered a new timeclock. When it arrives I shall pop it in and inform you how I get on.
Cheers again.

 

[shaka]

If the flow is getting to hot to touch but some heat is getting to some of the rads but luke warm the problem,to me as i have just repaired white star recently is the small heat exchanger at the rear of boiler cost £112 plumb center.

 

[Godluvsatryer]

Update;
The new digital timer has done the trick. £40 plus vat and postage or £30
Ebay. The Ebay one was not branded but identical and it works.
Thanks to everyone