Domestic Boiler Problem - Solution

[floydraser]

Some time ago I think it was Grendel who had a problem with a domestic boiler and I remember trying to describe a problem I had encountered which had similar symptoms. Well yesterday I had a repeat of the very same problem so I thought it may help others to relate the tale here:

I had no hot water and presumed we had used a lot so set the HW to boost for 2 hours. Still no hot water as the boiler failed to light. I checked the tank thermostat – ok – then the pilot light – ok – so it could still be a faulty thermostat, wiring fault or boiler. Turn up the central heating thermostat to trigger the boiler – nothing doing.

Ah, so it's the boiler but the pilot light is still there.

Do we call Julius Caesar and checkatrade? No. 

I've only ever had two boilers, both conventional gas types. On both, the pilot lights have been bi-directional; part of the flame points to the main burner and the other part to the Flame Failure Device (FFD). If either part fails you get nothing.

Another of my valuable brother in laws is a retired gas fitter, having spent his entire career working for the East Midlands Gas Board. He started my plumbing education when I was a newlywed in the late seventies, just after I drove a nail straight through a central heating pipe late one evening! He used to service domestic boilers and he told me there were two main parts to a service: checking the gas pressure and hoovering the dust, muck and ash from the boiler casing and burners. The ash is from cremated spiders and other bugs who thought they had found a nice, warm place for a kip on a winter's night, until your heating fired up in the morning...

Is this dangerous? Yes. So is driving a car but we still do that? Because we are educated to the risks and drive accordingly, so read on..

My boiler is an Ideal Gloworm from around 2007. The casing is held together with a mixture of wingnuts, self tapping screws/clips and captive bolts/nuts. Easy stuff.

Pic 1: case front removed revealing the slopey flue at the top, then the cast iron heat exchanger, then the heat chamber with white thermotiles and the main burner. I have also removed a panel from the front of the heat chamber which has a 4th thermotile on it, so I can get to the pilot.

Pic 2: The main burner with the pilot covered by a shroud. Just one nut to remove.

Pic 3: Left to right – Pilot jet, piezo electrode, FFD thermocouple.

The FFD needs a flame on it all the time to keep the gas valve open, or it will just shut the gas off. Have a look at the hole in the pilot jet and you can see a lump ash/muck.

Pic 4: From the top you can see how the pilot flame is directed in two ways.

Pic 5: Bingo! Compare the photos to see how it cleaned up. All I've done is to use an ordinary Henry with small nozzle to clean out the dust from around the pilot, go along the jets of the main burner and then inside the bottom of the casings where all the muck gathers.

No gas joints disturbed so no need to worry about leaks. If you are ever worried about leaks just ring British Gas and they'll be there like a shot, you don't have to tell them you've just had your boiler to bits!

I'm fairly confident at plumbing but I would never touch a gas system. The only way to check for leaks is by pressure check and I don't have the equipment for it.

The green sticker on the boiler is the price tag: £345.00 in 2007. Knowing a service is just a hoovering, I never have it serviced and this is the first problem I've had with it. The gas pressure was checked last year when we had a new cooker.

[Wussername]

GULP! 

I hope your neighbours are aware. 

[Regulo]

Why should the neighbours worry? These old faithfuls go on forever, unlike the new computerised rubbish that need new circuit boards every 5 years - if they last that long. What would be any different if the thing was looked at by a Gas Safe guy? He'd likely do exactly as Floydraser did. Possibly check for CO? I subscribe to the theory boiler servicing is unnecessary, if it ain't broke, don't fix it. (BTW, exactly what my aunt's Gas Safe engineer told her).

[Wussername]

Well said Regulo. We must unite against these scurrouless scaremongers 

[grendel]

on mine I did try hoovering it out, but the spark igniter just crumbled to dust, hence why I retired it.

[floydraser]

Regulo - I agree, they would probably check for CO but I'm not sure. I have a CO alarm positioned between the cooker and boiler.

Wussername - what would you do: Around 7 years ago we odered a new kitchen and the suppliers sent round their fitting contractors to asses the kitchen. A father and son team, dad was a gas safe engineer and the son a qualified electrician. Our cooker is fitted where the gas supply pipe comes up through the concrete floor like most of our neighbours with similar houses of the same vintage and builder. Our cookers have always been there and were to be so in the new design.

Dad: "I'm afraid the first thing I have to do is advise you not to use your cooker until I have had time to come round and move it to a different position, it's too close to an opening window."

Me: "It's always been there."

Dad: "Ah, but if you had the window open when using the top burners they could blow out and cause a gas leak."

???

[oldgregg]

That's what an FFD is fitted for, surely....

[floydraser]

2 minutes ago, oldgregg said:

That's what an FFD is fitted for, surely....

That's what I was thinking, then the son started:

Son: "I have to inform you not to use your electric shower until I've changed your consumer unit and installed the correct type of circuit protection." It already had the right protection.

OK right. As they had wasted my time and were clearly a pair of cowboys I told them to carry on with their quote. When it came through we cancelled the kitchen altogether, putting in a complaint about them.

We had a new cooker from Currys last year. The gas safe engineer who fitted it checked the gas pressure and asked if we had any other gas appliances as it was his duty to check those as well. I mentioned the incident with the other guy and he agreed, Cowboy.

[Regulo]

It's getting harder and harder to find tradesmen who don't want to rip you off with unnecessary work, and who do a good job for a decent price. It's the older guys who are reliable and responsible, I find, but as they retire you just hope you can get a recommendation for a good worker.

[floydraser]

Agreed again but in the name of balance I think the majority of tradesmen are honest and set out to do a decent job. The problem is avoiding the less motivated ones. I find word of mouth still the most reliable method.

[OldBerkshireBoy]

Agree with word of mouth from friends, family, neighbours and work, wouldnt believe all the claims about vetting and nice comments on these find a tradesperson sites as 75% are false.

[Vaughan]

Just a couple of comments if I may - from an ex CORGI fitter :

I wonder if all the muck in the pilot light housing was the result of trying to light the pilot with matches?  I don't know where such an accumulation would have come from otherwise.

Your photo shows what is known as the "flame picture" of the pilot light and shows a white tip to the flame.  This is "incomplete combustion" which means it is giving off CO and is dangerous.  An approved fitter will need to check this and probably change the jet.

After hoovering out the burner area you have not mentioned the flue itself, going up the chimney.  It is vital to have this regularly checked to make sure it is clear and drawing air as it should.  Especially as we can see that the pilot flame is suspect.  There are so many old gas fires in houses, that have been condemned and disconnected, not because there is anything wrong with the fire but because the flue has become in-effective and dangerous.

This sort of thing really is a job for a qualified fitter and I would recommend a yearly maintenance contract for peace of mind.

 

[Vaughan]

31 minutes ago, Vaughan said:

 An approved fitter will need to check this and probably change the jet.

 

By the way, he may also need to check that the air opening at the bottom of the pilot housing, opposite the jet, is set at the correct size, for the correct air/gas mixture.  Some of these older type are adjustable and it may have been disturbed, at some point.

[chrisdobson45]

I salute you, I haven't the courage to attempt to repair the boiler when it stops working. 

 

This reminds me of the hot air balloonist who was having difficulties one morning. He had to bale out and so leapt out of the basket and pulled the cord of his parachute, nothing happened so he pulled it again to no avail.

He sees, amazingly, a man travelling upwards, towards him at high velocity and shouts "Do you know anything about parachutes?" to which the man replies "No, do you know anything about gas boilers?"

 

[floydraser]

1 hour ago, Vaughan said:

Just a couple of comments if I may - from an ex CORGI fitter :

 

Blimey, is the anything this man hasn't done!? 

Fair comments Vaughan, I'll have another look later, just trying to fathom out how to get to the washer bottle on the Volvo.. any experience? 

I fitted the boiler myself with the help of a strong mate, to lift it onto the mounting, then brother in law made the connections and checks etc. it's been checked over several times since for instance as part of a safety review when we had cavity wall insulation done. Never been lit with a match, can't think why anyone would. I can't see any yellow in the flame now it's back together so maybe it was upset by not having it's shroud and casings fitted?

Fair point on the flue. It's a balanced flue and goes directly to an outside wall. Four bolts and I can get into it. This thread was about the pilot but I'll check the flue later. I appreciate your comments.

[oldgregg]

1 hour ago, chrisdobson45 said:

I salute you, I haven't the courage to attempt to repair the boiler when it stops working. 

Those older boilers are simpler, that's the main thing.

We used to have a 90's Ideal Classic with cast iron heat exchanger and it was a good old-fashioned 'heat only' boiler in that its job was purely to heat water. The only controls on it were a power switch and a temperature knob. 

Everything else was separate; expansion vessel, diverter valve for heating / hot water, programmer, pressure gauge, the lot.

The programmer literally applied power to the boiler and it'd fire up and heat the water on which ever circuit was selected. No data communication at all between the two, simply put 240V up it and let it do it's thing.

Spectacularly simple, I replaced the fan assembly on it myself when it failed and I was never really very worried that it would let us down as parts were available. 

Now we have a Worcester Bosch combi (part of a kitchen refit) and the instant hot water is convenient but that thing is massively more complex inside and so densely packaged to fit inside the housing that I can't see it lasting the 20 years the old one did at the point we decommissioned it.

[floydraser]

Our first and only other boiler was fitted by the previous owner of the house around 1975. It failed in 1992 when I was unemployed, on "supplementary benefit" and just about avoiding reposession. I stripped the boiler to find a cast iron manifold joining two cast blocks. All had coroded causing leakage. I cleaned up all the surfaces as best I could, applied bodyfiller and put it back together. When we were back on our feet we put some aside for when it failed again. What did I put above... 2007! 

I thank my dear old late Dad for allowing me to go and play in his garage as a child, to make whatever I wanted with whatever tools. And I still have all my fingers and most of his tools! 

[oldgregg]

You still see houses come up for sale with the old floor-standing boilers. They're not always amazingly efficient but they're insanely reliable and designed to be repaired rather than replaced.

And yeah, same here I guess. My dad is a qualified mechanical engineer so we were forever taking stuff apart when I was younger. Times were a bit hard in the early 90's (as you've alluded to) and I learnt to do all manner of jobs on cars and plumbing, electrics etc to save money and it was a bit of a faff at the time but it's incredibly useful nowadays.

[floydraser]

I seem to be having one of those retirements where you never get any free time.

Anyway, further to Vaughan's observations here's the flue from the outside:

Remove the four bolts and:

Oo look, there's the top of the heat exchanger. Mr Henry's been in there and cleaned up the detritus now.

So what is more dangerous: playing with the boiler or standing on the top of a step ladder using a Henry? I was wearing a hi-vis vest, goggles, hearing protection and I had notified rospa of my intentions. Honest!