Worcester 24CDi - burner cuts out

[buggslife]

My Worcester 24CDi combi boiler has started cutting out after a minute or two of running DHW. If you stop the tap and restart after a short break it will repeat again with a supply of hot water for a minute or so.

Any suggestions what I should look into?

Other threads suggested a partially blocked 2nd Heat Exchanger. So I had a look without taking it apart - see photos:

Untitled

• buggslife
• 10 Aug 2011
• 2

Untitled

• buggslife
• 10 Aug 2011
• 2

I would like to try and clean it out but would need some guidance on how first.

Do do the areas of limescale at the joints suggest build up inside?

Thanks in advance.

 

[ChrisR]

Do do the areas of limescale at the joints suggest build up inside?

No, those suggest..... leaks!. They can be inconsequential though.

The bad stuff in the heat exchanger isn't limescale, it's dissolved radiators, aka rust.

The way you've described the symptoms isn't typical, but a blocked hex is so common on a combi a few years old it's worth going in there first
The mfrs instructions do cover it, and this isn't a hard one, except that Worcs CDi's tend to leak once disturbed.

 

[buggslife]

Thanks Chris - the boiler was there when I moved in 4 years ago. Looking at the label I saw a 96 somewhere...if that is the year I'm guessing 15years is the end of its life span?

Should I be looking to replace the whole boiler?

Thing is, it has served me well and I am always keen to prolong a machine's life if possible.

I read the manual on how to replace the HEX but the process sounded pretty intense for me. COuld do with some extra guidance really - or call a plumber...$$$

Is it possible to flush the hex?

 

[OLLIE20]

When the hot water tap is running and it goes cold, does the red hot water light on the front of the boiler stay on or go off, if it goes off its most likely you diaphragm not a blocked plate

 

[buggslife]

The red light goes off along with the flame.

Also, it seems to be more of a problem with upstairs taps and shower - downstairs is often ok.

Still sound like a diaphragm problem? If so does it need replacing or cleaning??

 

[Agile]

Yes!

But thats not viewed as a very easy job even for a professional and I charge a lot more than my usual £106 for a similar fault on other models.

I have to allow about 2 hours + !

Tony

 

[buggslife]

Thanks Tony - so not highly recommended I try it myself?

I came across a kind of guide where someone did it here:
http://www.newtonnet.co.uk/house/boiler/

Does this seem good to you?

 

[boilerdoktor]

i do them in about 45 mins but i ve done hell of a lot over the years and charge about £180. (only to let you know how much lads charge so you can decide for yourself whether its worth doing it yourself or not!)

your auto air vent may leak when you fill back up beware! do not touch the isolation valves!!!!! that piece talks about removing the bypass! don t do it!! it can be murders to get back in!!!

good luck

 

[buggslife]

Thanks for the advice.

Oddly, the boiler was working fine over the weekend with uninterrupted hot showers. Yesterday it started playing up again.

Does the intermittency tell us anything?

If it definitely sounds like the diaphragm then any tips on buying a replacement? Ebay?