New Cylinder needed for system boiler fitting?

[jkn]

Hi Roger

The main boiler flame seems pretty yellow (and I think the window for examining the pilot light is sooted up) - which is where I came in, I recall it being much bluer a month or two ago, when I fitted the thermocouple etc.

The pilot light looks nice and blue. I haven't yet taken off the front shield to better look at the flames.

Yes, I appreciate the difference, thanks. I have just bought and added some Sentinel 'boiler noise reducer' from Toolstation. I drained a bit of water from a rad whilst tying up the ball valve in the Overflow tank, then added this stuff to the tank.

I'd probably try to clean the heat exchange myself if I could find the right brushes...

Thanks, J^n

[Tim+]

You know, this sounds really quite dangerous. If you don?t have a carbon monoxide alarm get one pronto!

If I?m right in thinking this is an open vented boiler it could well spill combustion gases back in to the house.

As I?m sure you?re aware a yellow flame means that the gas/air ratio is too rich. Whilst occasionally gas regulators can go wrong and deliver too much gas, it?s more likely due to poor air flow through the boiler.

This can occur on the inlet side if it?s choked with fluff (which is easy to see and cure) but it can also occur due to a sooted up chimney. Once you have a situation where soot is settling in the chimney it creates a positive feedback loop creating more and more soot.

Until you?ve got this situation sorted be very careful about using the boiler. It needs a service urgently and the chimney almost certainly needs to be swept!

Tim

[jkn]

Hi Tim Yes, I am somewhat aware of the issues - in fact I fitted a (new, fancy) CO alarm when I replaced the thermocouple. It even has a graph of CO level ... which has always shown zero.

I am not complacent about that - partly why I'm asking here, TBH, as I'm not sure that just 'cleaning the Heat Exchanger' is the answer.

Thanks for the warning

J^n

[jkn]

Update, FWIW I was able to do most of a 'servicing' of the back boiler today. I bought myself a set of brushes from Toolstation and followed the non-gas related part of the installation & servicing manual. I cleaned a fair amount of soot out from the heat exchanger; I think the reason the flame was yellow was that there was a lot of fluff around the lint arrestor (a very impressive name for a bit of metal gauze!).

After all of that the main flame looks an awful lot better, and (in conjunction with the 'boiler noise reducer') the kettling is much improved, although not wholly gone.

I will look at getting a proper servicing done, and will carry on researching a new system boiler/cylinder combination. Thanks all for the advice.

Cheers, J^n

[Fredxx]

TBH all a service engineer would do is clean things in the manner you describe.

Can you confirm there is no longer any yellow in the flame?

Is there a flue liner? Either way I would be tempted to get a CO monitor for the (bed)room above too. Although likely to be unnecessary it provides a boot and braces approach to safety.

[jkn]

Hi Fred

Yeah - I watched what my service guy did a couple of years ago. He did check the updraft with a taper as well, and (I think) checked the pressure. He seems to have gone AWOL recently though, I haven't been able to raise him.

Not sure I can say there is *none* - the flame as it comes off the burner is blue, but there are yellow 'tips' to the ends of the flame.

There is no fireplace upstairs, if that is what you mean? But yeah, perhaps a good plan in any case, there is definitely a smoke alarm upstairs.

Thanks, J^n

[Fredxx]

I'm going to suggest there is incomplete combustion, and the burner needs a more thorough clean. I believe there shouldn't be any yellow.

My thoughts were more leakage from the flue into the room above. I have known cracks in brick and plasterworks that have compromised the effectiveness of the flue.

[newshound]

Ancient cylinder and maybe not well insulated? Probably worth doing unless perhaps it is a particularly difficult replacement.

To answer a different question, I'd never fit a combi at least in any property that had room for a cylinder, I'd always go for system.