problem with worcester bosch 24 boiler

[Ian & Hilda Dedic]

Hi Chaps, the last couple of mornings my relatively new (4 years old) Worcester Bosch 24 boiler has failed to come on in the early morning.

The thermostat seems to be working ok and the timer unit seems to be sending signals, but the boiler does not ignite.

At first I thought it might be the fuse to the boiler, so I changed that and after turning the dial on the front to zero and then back on again the boiler fires up ok and seems to work correctly all day.

Then last night, it was working fine just before I went to bed but nothing this morning until I did the dial thing again.

So Have you guys (and gals) come across anything similar?

Is it time for a service? I'm ok with electrcals/electronics tests but I'm wary of gas appliances, so I'd like to see if there's an explanation so I don't get ripped off if I have to call a bloke in...

dedics

[Stuart Noble]

After 4 years might be best to bite the bullet and get a WB engineer. For £200 they replace up to 3 major parts. IME they replace whatever's failed plus 2 other bits that might go. Given the cost of the spares, it can stack up well against getting a local engineer.

[Lobster]

Isn't that a combi boiler?

If so, has it lost pressure - there'll be a pressure gauge on the front of the boiler - what does it say?

David

[Ian & Hilda Dedic]

no I don't think so, we don't have hot water on demand-- we have a separate hot tank upstairs,and there's no visible pressure gauge on the outside.

Its full designation is worcester bosch 19/24 CBi

Having said that, it's behaved fine all day, it just wasn't coming on first thing in the morning. (Brrrrr)

Maybe its something to do with the system being completely cold at the start point.

I had a look at the servicing manual, and my thought was perhaps it did need a service anyway, so I might ring the chap who fitted it for us and see if he'll come and give it the once over.

dedics

[Ian & Hilda Dedic]

Hi chaps here's some further diagnostic info,

the boiler works fine all day but does not start in the early morning when all is cold.

however, turning the power supply to it off then on again at the wall switch, and then using the rotary switch on the front to reset allows the boiler to start again.

just reset on it's own isn't sufficient.

Any further ideas, I'm thinking its something that's too far apart when cold but expands to close the gap when warm.

all responses gratefully received.

and thanks to all who've responded so far.

dedics

[John Stumbles]

It may be only 4 years old but it's a pretty ancient design. Most of the recent pre-condensing W-Bs have lightweight heat exchangers but this has a cast-iron one.

Had one of these a year or so back which sometimes wouldn't start up. In that case it turned out to be a PCB fault and we got a replacement from geoff (CET Ltd). IIRC the PCB was sometimes failing to generate HT for the spark ignition. I don't know if this is a stock fault (but I'm sure geoff will be along in a minute if it is)

[geoff]

not the commonest, but certainly a fault we see from time to time

I held back on answering the OP because there was no indication as to at what point in the sequence it was failing

[John Stumbles]

I'm not convinced it's the PCB but it sounded so similar to the fault I'd seen on one I thought it merited a heads-up.

[geoff]

It's a difficult one

Could be down to expansion / contraction in a broken wire or something stupid like that