Worcester Bosch 24CDi Boiler - Cold Water Flow Switch

Our CH boiler has stopped heating water for the household taps the CH is still working normally. The symptoms are as follows:-

  1. Turned of the ch and turned on hot tap it did not switch inself on but initially got a small amount of hot water. Did it again and this time just cold but again it did not switch itself on.

  1. Switched on ch and waited until boiler not running, turned on hot tap and it did fire up the light came on and I got a shot of hot water which then went cold?

  2. A small amount of water is dripping from under the boiler.

A friend reckons we need to replace the cold water flow switch. What do you think?

Cheers,

Bren

Reply to
Bren
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In message , Bren writes

I think you should find out where your drip's coming from and find out if your cold water flow switch is working (I can't remember whether it just goes short circuit with flow or whether it gives out pulses

What is the diverter valve doing ?

Reply to
geoff

I think you need to replace your friend ;-)

IIRC the CDi has a plate heat exchanger and diverter valve: you should be able to see the pin of the diverter valve actuator moving out from the brass body of the valve towards a microswitch (partly shrouded in a plastic cover). It's probably not moving far enough to operate the switch and you need to replace the diverter valve - or, more easily & cheaply, its diaphragm (available from BES, besides others).

Reply to
YAPH

There is no cold water flow switch as such on the 24cdi.

First place I would start would be the change over valve. Most likely to be damaged diaphragm.

If the diaphragm is damaged then the cold water demand will not allow the pin to activate the micro switch which switches on the burner.

It is not a simple diy job to fit a new diaphragm or change over valve. Would be better to get a boiler technician in to diagnose/sort the problem out if you or your friend are unsure.

Reply to
Heliotrope Smith

Most likely a perished diaphragm in the diverter valve.

I documented my own such repair at

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you want an idea of what's involved. I receive several e-mails a week as a result of that page from people who have done the job themselves and so whilst it is not the easiest of jobs it does appear to be within the ability of many.

The drip however is something else - you need to find out where that's coming from.

Mathew

Reply to
Mathew Newton

Most likely a perished diaphragm in the diverter valve.

I documented my own such repair at

formatting link
you want an idea of what's involved. I receive several e-mails a week as a result of that page from people who have done the job themselves and so whilst it is not the easiest of jobs it does appear to be within the ability of many.

The drip however is something else - you need to find out where that's coming from.

Mathew

Thanks for the replies.

The consensus seems to be that the diverter valve is at fault or, more specifically, the diaphgram. In view of the potential problems and complexity of replacing the diaphgram would it not be easier and simpler to replace the whole valve? I am assuming that a replacement valve comes with a fitted diaphgram. I realise that it is more expensive than just replacing the diaphgram but I am not confident of my abilities to just replace the diaphgram.

Bren

Reply to
Bren

Contrary to what my site may say I would actually recommend replacing the whole diverter as it could save you another problem further down the line. It will indeed be easier and you will almost certainly be removing the diverter anyway (it is possible to replace the diaphragm in-situ but it takes the right tools and a certain amount of manual dexterity and having done both ways wouldn't recommend it.

I know my site disses the repair-by-replacement approach but when I wrote all that I had all the time in the world... Now that I have a few more responsibilities (and money) I am gradually changing my ways! I probably ought to update the text to something more balanced. Furthermore, new diverters often sell via eBay for

Reply to
Mathew Newton

Contrary to what my site may say I would actually recommend replacing the whole diverter as it could save you another problem further down the line. It will indeed be easier and you will almost certainly be removing the diverter anyway (it is possible to replace the diaphragm in-situ but it takes the right tools and a certain amount of manual dexterity and having done both ways wouldn't recommend it.

I know my site disses the repair-by-replacement approach but when I wrote all that I had all the time in the world... Now that I have a few more responsibilities (and money) I am gradually changing my ways! I probably ought to update the text to something more balanced. Furthermore, new diverters often sell via eBay for

Reply to
Bren

In message , Bren writes

Replacing a diaphragm is almost very easy

The almost bit is that one thing you didn't document

Reply to
geoff

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