Worcester Highflow 400RSF

[keego]

Just been to one tonight as a favour to a friend, as a rule I don't normally do breakdowns especially on combi's.
Anyway the fault is no heating, hot water is fine, I've been through the fault finding chart in the MI's & it's ended up as saying replace the demand indicator. Now as far as I can see the demand indicator is just a neon so how can that stop the boiler from firing up if it is U/S?
As I've said, the DHW is fine but there is no response at all for CH even though there is 230v from the programmer & the room stat is still linked out on the board.

 

[superdupergasman]

Are you sure you have checked everything that the MI's tell you to check properly and not guessed??

 

[superdupergasman]

Have you checked flow switch with multi meter??

Are you getting power to the divertor valve solinoid??

 

[keego]

Not checked any of that, me being a mere installer I just go where the book tells me
In the MI's (fail point J) it tells me to set the programmer to DHW & CH but to keep the Water stat turned down, then if the demand light does not light then check pin 4 of X2 for 230v(present), then go to pin 2 of X13 & check for 230v if yes then check pin 5 of X3 for about 90v (found 130v) so if the voltage on pin 5 of X3 is OK then replace the demand indicator.

 

[superdupergasman]

Common faults with these boilers are:

Flow switch jammed on and keeping it in HW mode.

Divertor valve not opening up thus not water getting to the CH circuit.

There also could be sludge in the weep tube going from the divertor valve into back of pump causing divertor not too open.

There is also a filter in the return isolation Valve, this could be sludged up.

The boiler stat for CH could be buggered.....

There is a long list of fault on this boiler.

I would call worcester and get them to take you through the fault finding over the phone.

Make sure you have a Multi meter and know how to use it if you call them!

 

[keego]

There is a long list of fault on this boiler.

You aint kidding!
While I was there yesterday I found that the expansion vessel was knackered, I know this had nothing to do with the fault but it needed changing so I got one today.
Went back tonight to fit it & have another look at the boiler & found the CH stat on the boiler faulty, linked it out just to test it & the boiler fired up & started banging & then went to overheat so it looks like the diverter has gone as well.
Combi boilers.....don't you just love them!