Typical 'daddy, please help' call from the daughter this morning. Her Alpha CB24X combi (don't laugh - it was in the house when she bought it) is apparently having some difficulty 'catching' when hot water is demanded, although she insists that the CH is working ok. Described symptom is that it just keeps going "whoosh" as though starting up ok, but actually doesn't fire up, resulting in cold water from the tap.
I have not the faintest idea where to start on this (other than suggesting Yellow Pages which I'm sure would go down like a lead balloon ...)
Is anyone on here familiar enough with this boiler to make any suggestions as to anything that's common to cause this problem ?
Very vague memories of one in a rented flat that exhibited similar problems. Down to a blocked inlet filter not allowing enough pressure to a pressure switch IIRC. I do remember commenting to the guy who fixed it that it was a nice change to see bits like this which can fail mounted in a nice easy to get to place ... unlike some boilers.
Something like this is probably cheaper and less hassle than the yellow pages option. Ringing local fitters on their mobiles and being answered with a grunt gets tedious.
Thanks Tony. That's an interesting comment, as the hot flow pressure always has seemed a little limited. Anyone know for sure if this boiler has such a filter, and where it might be located ?
Don't s'pose a schematic diagram for a CD24C/32C would be any help in suggesting where this filter might be ...I have one if it does help so could put it on Photobucket.
I am not familiar with the boiler... but if the heating is working ok, then that would usually point the finger of suspicion at either the HW flow detection or the diversion valve.
Aha, got the installation and service manual for it here if that is any help. Drop me an email if you want a copy and I will send it by return.
The flow switch appears to be to the left of, and slightly higher than the top of the main circulation pump.
Thanks for the offer. I seem to recall now I think about it, that I actually have a full manual for this boiler that I downloaded from the Alpha website when she first moved in. I'd completely forgotton that. As it was a full manual, it might well have diagnostic flow charts in it. I'll do a search on the computer right now, to see where I put it :-)
Thanks for the offer John, but I've just found a copy of the manual on the computer here, that I downloaded when she first moved in, and that I'd completely forgotten about.
I have been cajoled into going round there tonight to see if I can see anything obvious, but as I have been at pains to explain to her, I'm not a boiler engineer and if it's not something that's obvious, then she's gonna have to fight back the tears, and get her wallet out ... Hell, I don't even really understand fully the 'combi' boiler system. I am just about familiar with the basic principles, but I have little knowledge of the finer details. I can cope with a 'traditional' CH / indirectly heated domestic water system, but all this heating water on the fly and diverter valves and what not, all leaves me a bit cold (no pun intended ... !!)
I guess the obvious place to start would be to check the flow switch switches and stays switched all the time the tap is on. It may be it just pulses on for a bit and then lets go.
(basically it should cause two things to happen - fire the boiler if not already running, and activate a diversion valve that redirects the normal flow and return through a small plate heat exchanger rather than the radiator circuit. This in turn should heat the incoming mains cold water (albeit relatively slowly at 24kW).
"Described symptom is that it just keeps going "whoosh" as though starting up ok, but actually doesn't fire up, resulting in cold water from the tap."
could be a number of things, (bit of homing in req'd ) but it could be the pilot being blown away from the electrode when the gas from the main valve ignites (pre-ignition)
Does the spark stop or keep going when it lights ?
Yeah, I saturated the thing in it, but it just buggered all the pots in there ... :-) (private 'joke' for newbies ... )
I went round last night, but it's hard to say exactly what is happening - well for me anyway, as I don't have a great understanding of these combi boilers. She had just started up the washing machine, and when that demanded hot water, the boiler seemed to start and fire ok, although I'm not convinced that the combustion blower sounded as 'intense' as I thought it would. A minute or two later, it all stopped. It tried to restart, and was definitely lighting, but didn't seem to be able to maintain. The indicator "A" and "B" lights on the front indicated the right things for a startup, but eventually, it gave up, leaving, I think, a steady "B" light which according to the user manual indicates "main burner failed to light". The manual then goes on to say that you should be able to re-initiate the boiler by turning the selector switch to the "reset" position. Although that resulted in internal clicks from relays or solenoids, the re-start sequence didn't commence. She says that this is always the case, and it is necessary to cycle the mains power. When I did this, it re-started, but with the same 'I might keep running - I might not' sort of performance.
Apparently, she has always had trouble getting enough temperature on the hot water up in the bathroom, and has difficulty drawing a full bath that is warm enough to sit in for more than a few minutes. The shower is not so bad, but still not good. The pipe run is not long. It's only a small house, and the bathroom is pretty much right above the boiler. About the only other thing is that the boiler is not original in the house, but it seems to have been properly and professionally fitted, in place of the original CH / indirect water system that has obviously been removed.
In view of the problems that the system seems to have, and which may now have become bad enough to manifest themselves as a proper fault, I'm thinking that she might be best to just get in a professional, who understands the system properly, and is able to carry out a valid diagnosis and repair, in a safe and timely manner. My main object in posting here, was just in case there was a 'stock' fault for this boiler, that was well known amongst the heating engineers, and was something that I could easily DIY fix. Whilst I am happy to tackle most plumbing / electrics / carpentry / general DIY work, I am aware of my limitations, and I think that this problem is probably beyond them ...
Well, this particular daughter is in business with the wife, and is not short of money, but because of the type of work that I do for a living, and for as long as she can remember, I have always fixed just about everything that has gone wrong in my own house, she considers me to be "Mr Fixall", and can't understand it when I tell her that anything is outside my realm of expertise ...
So, if I can't do it based on some valuable information that has now come to me by direct email from another poster, then she's gonna have to get someone in, and pay for it herself !
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