Worcester 28CDi RSF Combi-Boiler (gas) problem....help !

[Pete@]

Hi,
I have a Worcester 28CDi RSF Combi-Boiler (gas) which I have a problem with.
I had a plumber come to look at it yesterday and he told me that I should replace the boiler as it would cost more than it is worth to fix it.
The plumber is not someone I know, and fair enough, if it needs a new boiler then that is what we will have to do, but I'd like to a second guess on this before I spend money that I can't really afford.

I am an experienced mechanical engineer and understand that things go wrong, perhaps I should just stop rambling tell you about the problem and ask for your opinion !?.

For a little while now (since around xmas), the central heating side of our boiler has been playing up. It runs for around 5 to 10 minutes and then gives a boiler lockout error (red light flashing).
If I reset the error, the ignition system will try to light (there is a good consistent spark), but it fails to light (almost as if there is no gas coming through) and the lockout error continues.

The hot water side of the system is fine, although it does sometimes cut out with the same type of issue.

It is almost as if the system is overheating and shutting itself down.
If I isolate the system for a while, (until it has cooled ?), I get the same symptoms over again (can't get past those first 5 to 10 minutes).
The radiators become warm, but not hot (no blockage or water pump issue ?).

The plumber says that it is a faulty heat exchanger, and would cost around four hundred to replace, ok I've looked at the cost of the spares and can accept this.

Does this sound right ?, is there something I can try (reasonable electrical and mechanical) just to make sure the problem is the heat exchanger ?.

I don't want to waste more money getting a second plumber in if he is just going to confirm the original diagnosis.

Gents, I would really appreciate some sound advice.

Thanks
Pete

 

[Blake]

How did he come to the conclusion it was the heat exchanger at fault? Did he carry out any tests on any of the thermistors in the boilers to confirm everything was working as it should before concluding the HE was blocked or faulty as your stated?

Also, if the HE is blocked then this would suggest that your CH system is perhaps dirty, which means a clean is needed. A new boiler will require a clean system also, so why not get your system cleaned and then see if that makes a difference. If not, nothing lost as it will be clean ready for a new boiler if needed.

 

[Pete@]

Hi Darryl, thanks for the reply.
I know he did some testing, but I wasn't there to witness it. He spent around 10 /15 mins testing, can he diagnose this without any sort of a strip down ?.

If I sound suspicious, I'm not, I just don't want to waste any more money than I need to.
Is there any simple thing that I can do to confirm that it is the heat exchanger or not ?.

I've looked in the manual that came with the boiler, the fault signal seems to point down the line of an electrical fault.

He did make the comment that it was very clean, but I don't believe that he had even taken the inspection (the gas tight) cover off.

 

[Blake]

The problem is many things can lead to the symptoms you describe. Does you boiler 'kettle' prior to turning off? any loud thumping noises etc to suggest it is overheating?

If the rads are not getting very warm then the diverter valve could be at fault as it may not be sending the flow around the heating circuit, hence overheating.

Like I said, difficult to diagnose without seeing it. You may want to consider another engineer for a 2nd opinion to confirm what the first engineer diagnosed as he may be right, but as we all know, there are good and bad engineers out there.

 

[Blake]

If I was the engineer, I would have taken a look at the condition of the CH water and if it was found to be dirty, I would have suggested some cleaning chemicals in the system to see if that made a difference.

Did he/she make any reference to the condition of your water?

 

[Pete@]

We live in a soft water area, so I didn't think that build up was an issue.
The boiler has always been a bit noisy, but the noise doesn't increase just before it fails.
The plumber did use the word kettling to the missus (I presume this means that it is overheating, making a noise like a boiling kettle ?).
I think that you have confirmed what I first thought, that he was a bit quick to jump to the "scrap and replace" option.

 

[Bartdude]

Has the pump been checked?

 

[Pete@]

Not to my knowledge, as I said in the threads above the plumber attended for about ten minutes tops (I wasn't at home to see what he did).
Is there a simple way that I can test the pump.
I thought that if the downstairs rads were getting warm, then the pump was working (even if not too well), could this be the cause ?.

There is a thermostat on the top of the heat exchanger, could this be telling the boiler that it is overheating when actually it isn't ?.

 

[Blake]

At the end of the day, the boiler is a few years old and if it does require a repair over say £2-300, I would consider putting that towards a new condensing combi rather than repairing it.

If it turns out to be a sensor/thermister issuue, then it's not that expensive.

Get a 2nd opinion and take it from there.

 

[Blake]

The problem is Pete, for your own safety, we are not going to encourage working on your own boiler I'm afraid. But yes it could be a lazy pump, dodgy thermister/sensor/div valve etc etc.

You need to get a 2nd opinion.

 

[Pete@]

I appreciate the advice. No I'm not going to start stripping it down, I'd just hoped there might be a simple way to make sure what he was telling me is realistic.
A second opinion it is !.
Believe me I am very grateful for the help.

 

[Blake]

you are welcome, hope you get it sorted

 

[MR RIGSBY]

Which light or lights flash, also how fast do they flash?

Its unlikely to be an overheat fault if the hot water runs ok.

 

[Rachelplatt14]

Hi,

I have exactly the same problem with my boiler and I am positive it is an electrical fault.

I'm pretty skint, so have had to put up with this problem for a while and I have found a work around, which is to push into the bolier (with hand/foot) whilst it it trying to light. This seems to temporarily fix the loose connection enough for it to get fired up and once it has been going for 30 seconds or so it will then stay lit, until heating/hot water is turned off.

So my question is what part do I need to replace to get the boiler working again properly? I know a fully qualified electrician who would be able to fit it for me but I need to purchase the part in question.

Thanks,

Rachel

 

[Dotty]

Hi Rachel and welcome to the forum.

While your friend might be a fully qualified sparks he's not an RGI. for him to go poking around in your boiler could place your life at risk, no matter how well intentioned, plus some faults could be caused by any number of components so we could inadvertently cost you more than you should be paying. I understand money's an issue, ask your friend if he knows anyone in the gas trade that could help you out, he probably does.

But please make sure he's Gas Safe registered! It's your safety we'd be worried about most!

Gas Safe Register | Ensure your gas engineer is registered.

 

[Barry98]

Might help if you say where your from too , Welcome to the house of fun too