Wdumff Noise from Boiler

Hi all
Noticed yesterday that the boiler made a couple of wdumff type noises and wondered as to the cause. Boiler is Worcester Bosch Greenstar 24Ri, powering a vented heating and hot water system. After the wdumffs, the boiler went into alarm mode with the blue indicator light flashing quickly. The noise *appeared* to be coming as much from the connected pipes as the boiler itself.
The system has 3 zones, upstairs heat, downstairs heat and HW. At the time of the problem, it was serving the downstairs heat only. As I have the hall rad off ATM (and all other d/stairs rads have TRVs), I thought it was the boiler overheating due to lack of flow. But, there is an auto by-pass valve in the airing cupboard - after the pump but before the 3 zone valves - which I thought should allow for this! When I noticed the problem I ran upstairs to check out the by-pass valve, and the discharge pipe was well hot!
Anyone any suggestions please?
TIA
Phil
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TheScullster wrote:

Sounds like it could be a delayed ignition problem leading to a build up of gas which is then igniting semi-explosively.
I don't know that boiler's ignition sequence but we had a problem once with a gas valve sticking open slightly allowing gas to enter the main burner before the ignition pilot had lit. It could be that something similar is happening with yours.
You can download a technical manual here:
http://www.worcester-bosch.co.uk/installer/products/gas-boilers/greenstar-24ri
Fast flashing blue light means "volatile lockout" for what it's worth. Anyhow, I think the bottom line is that it needs seeing to and if you want CH over Christmas you'd best get on the phone ASAP if this isn't something you can fix yourself.
Tim
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"Tim" wrote

Thanks Tim, but I don't think it's an ignition issue, as I have experienced that before with another boiler/house. Ignition seems smooth and can be identified by the high speed ticking of the electronic spark generator immediately prior.
The noise I am hearing sounds more like a violent movement of water.
Phil
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On Tue, 15 Dec 2009 11:59:55 +0000, TheScullster wrote:

Condensate waste pipe frozen?
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John Stumbles -- http://yaph.co.uk

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"YAPH" wrote

Thanks John, but this noise seems to emanate from the boiler and/or the feed and return pipes. The condensate trap does make some weird and wonderful noises, but this is quite different. I thought that the boiler would shut down if the condensate couldn't get away! It is a rare occurence, so getting someone to witness the noise would be difficult.
Phil
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On Tue, 15 Dec 2009 13:38:09 +0000, TheScullster wrote:

Have you actually checked that the condensate waste isn't frozen or blocked?
IME [some] W-B boilers don't shut down, the heat exchanger just fills up with water with 'interesting' (though not lethal) results.
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John Stumbles -- http://yaph.co.uk

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On Tue, 15 Dec 2009 22:01:52 +0000, YAPH wrote:

Funnily enough I had exactly that the other day (but with a forced-air furnace[1], not hot water). There was a crude[2] filter between the furnace and the condensate tank/pump, and it had clogged up. Took the drain plug out, quick proggle and good as new (until the next time)
[1] Although "Wdumff" is *exactly* what it does once in a while. Dunno if it's when the wind's blowing a certain way, or when it's a certain temperature, or what - it just does that sometimes (but no blinky lights like the OP had)
[2] basically a small box with an inlet and outlet - it didn't tell me to feck off or anything.
cheers
Jules
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[snip]

AFAIK, they are not manufactured in Ireland :-)
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FERGUS O'ROURKE
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I got to hear gurgling noises before the air flow sensor shut down the boiler!!
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TheScullster wrote:

As long as its not going kerrrsloooosh. Thats serious.
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Dave - The Medway Handyman
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BANG is to be avoided as well ;o)
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Tinkerer



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