length of time from gas valve open to flame

[chrisw99]

Had the dreaded ignition lockout a couple of times randomly recently, but it's never done it when I've been watching as I've been trying to determine if it happens pre or post ignition.

I've been monitoring the startup pattern... heating on, pump starts, fan starts, air pressure switch clicks, gas valve/relay louder click then a few seconds later the flame ignites.

However, I've noticed that the length of time between the gas valve click and the flame appearing seems random, anything from instantly to several seconds. What is the cause for this delay? I'd have thought as soon as the ignition PCB opens up the gas it would ignite it at exactly the same time every startup.

It's a Halstead Best 50. New gas valve/ignition PCB 12 months ago. New aquastat PCB, thermistor, flame sensor and ignition cable 4 months ago.

Last time I got the ignition lockout, turned out to be a sticking gas valve which was why that and the PCB were replaced 12 months ago, but when that happened the boiler tried to light several times before giving up and locking out. This time the lockout seems to happen almost instantly and straight away rather than after a few retries.

But back to my original question... is the fact that the flame lighting can vary from 1 second up to a few seconds a clue or a red herring?

 

[Aquaheat]

It's a clue.

 

[chrisw99]

It's a clue.

Ok, getting somewhere. What does that suggest? What would the logic on the PCB be waiting for before igniting after it's opened the gas valve?

 

[Jackrae]

The igniter circuit should be active before the gas valve opens otherwise you'd get a 'bit' of a bang with a delayed ignition

 

[chrisw99]

The igniter circuit should be active before the gas valve opens otherwise you'd get a 'bit' of a bang with a delayed ignition

True, if gas really had been entering the chamber for 7-8 seconds there would be quite a bit of build up in the chamber.

In that case, the loud click I hear on startup presumably isn't the gas valve opening as I'd assumed. What is that click likely to be? In summary the sequence of noises is - pump runs, fan runs, small click near top right (air pressure switch?), very loud click near lower right, the wumph when it lights.

What is the loud click?

 

[Jackrae]

The gas valve opening will be the loud click
You might be able to hear the igniter system clicking rapidly or it making a sizzling sound a couple of seconds before the gas valve opens.
Chances are your ignition system is probably faulty
But, as other will advise, your "Gas Safe" technician is the guy to sort things out.

 

[chrisw99]

The gas valve opening will be the loud click
You might be able to hear the igniter system clicking rapidly or it making a sizzling sound a couple of seconds before the gas valve opens.
Chances are your ignition system is probably faulty
But, as other will advise, your "Gas Safe" technician is the guy to sort things out.

My gas safe technician is BG home care plan, who charge £99 for every visit. Great if it needs an expensive part replacing as with the gas valve + pcb last year, not so great if it turns out to be an airlock, or any other cheap fix like I once discovered.

If the loud click IS the gas valve opening as you say, then why does it then sometimes take 1 second to then see the ignition spark and some other times 8 seconds? I can see the spark and the flames through the inspection window.

Using a combination of what I can see and what I can hear, I would like to try and diagnose what it could be and what I can rule out, before judging how to proceed. We intend to replace this boiler next spring and are saving up for that. After the recent fixes and the fact most parts are new, I was hoping it would last out that long. A bit dismayed to have a cold morning and see that red lockout light has come on again. Deja vu after last autumn. And BG were arsey then, as it wasn't a repeatable fault, just happened "sometimes" so they had nothing to go on so just replaced part after part (great for me though) until it stopped.

 

[durhamplumber]

So you pay your money to British Gas each month to repair it rather than an independent,,,,but you expect independents to give you free advice when BG will not.A most interesting philosophy.pay me £50 every month and I will throw Parts at it forever

 

[Dan Robinson]

Sometimes on these threads, words just fail me

 

[chrisw99]

So you pay your money to British Gas each month to repair it rather than an independent,,,,but you expect independents to give you free advice when BG will not.A most interesting philosophy.pay me £50 every month and I will throw Parts at it forever

Er not quite it's 3 pounds per month and that includes the annual service. It's then 99 pounds for a call-out even if they don't do anything and just give advice. Which is what I'm anxious to avoid especially as I'm saving for a new boiler.

I thought the whole point of these forums was for advice??

 

[Dan Robinson]

that includes the annual service

That's what they tell you anyway

 

[Dan Robinson]

I thought the whole point of these forums was for advice?

That's what they tell you anyway

Consider that some advice .

 

[chrisw99]

That's what they tell you anyway

Very true. In fact it was their annual service this year when they accidentally sliced through the ignition cable putting it back together, which caused me to have another £99 to fix that and instead of paying the £11 for a new ignition cable, they stuck it together with tape and then pulled out the flame sensor putting it back together, leading to another £99 callout where they then told me I needed a £750 powerflush because there was a blockage causing the boiler to overheat when there was no such thing. I was successful in my complaint and got both those callouts refunded, and the £33 it cost me to source my own flame sensor and ignition cables.

At that point I decided enough was enough, and I'm saving for a new boiler hopefully next spring. Still, the £3 a month cover has had it's uses, the broken gas valve last year + pcb + aquastat was £600+ worth of parts for a £99 callout so in the end I'm probably about £400 up since I took out the cover.

But it's the fact they are total idiots that really pains me having to call them out again, especially as there's no fault for them to look at , just a random lockout that occurs perhaps once a week.

 

[durhamplumber]

But it's the fact they are total idiots that really pains me having to call them out again, especially as there's no fault for t

so you pay money to people you consider total idiots...And what does that say about your intelligence?

 

[chrisw99]

so you pay money to people you consider total idiots...And what does that say about your intelligence?

I paid the money for the parts cover to be honest, £3 month is peanuts and I've already had several hundreds of pounds more in return than I've invested. It's just that I have to rely on them to diagnose and replace correctly.

I think I've had the fan (£180), pump (£200), gas valve (£300), PCB (£140) twice, aquastat (£150), and lots of smaller bits. Probably totalling £1000 in new parts, replaced.

As soon as I get a new boiler I hope to wash my hands of them, but for now whilst this one being obsolete has such pricey parts, it makes good sense.