Sooted Thermecon W40/50

[Paffman]

Hi all,

Please can you throw some light on this problem ?

The background......

Thermecon W40/50 internal wall mounted. Fitted in a cupboard in an upstairs bathroom, no vents in the door or wall. Told customer that there should be some. Supposed to have been 'serviced' 4 months before I got the call that it had locked-out and was kicking out soot. Customer could not find the service paperwork.

Got there, spent most of the time de-sooting that SOB.

It was in the bathroom upstairs in a cupboard that the bottom was three feet off the floor, so spent the morning up and down steps and bent double. Covered in soot and one and a half henry bags later, I never seen so much soot. The bottom baffle lip on the combustion chamber was almost burnt through - just an inch left, the plastic air tube where the snorkel fixes was a bit melted. Nozzle in there was a 0.50x60*W, difuser to nozzel was 12mm, pump pressure 140psi.

Put a 0.45x80H in at 115psi, CO2 @ 11% - as per customers manual.

Customer said it now does not shake the house when it fires up !

Apart from the above when I went to re-fit the snorkel, the flappy bit at the end folded in and blocked off the air, so removed and made sure this was outside. As the customer said that the other service man had left it off and he refitted it, maybe when the customer refitted it blocked off most of the air ?

I left it running OK on 27th March, now a month later he rings me again to say it is just as bad as before kicking out soot.

It is supposed to be a 4yr old boiler.

Got to go back tomorrow...

Should the bottom baffle have a drop down leg that rests on the combustion chamber baffle lip?

Thanks in advance.

 

[WDIK]

snorkle? is this some form of ducted combustion air from outside?

did you take the readings after you fitted it?

 

[Paffman]

Hi,

Yes it is a snorkel system, looked clear and the FG was checked when it was fitted.

I can't think what to do next, maybe as there are no vents in the cupboard, when the door is closed it is choking its self?

But then it must have run OK when it was fitted.

BTW the customer has only lived there for two years.

I still think it is funny that he could not find the paperwork from the guy who was supposed to have serviced it 4 months ago?

If it was me I'd be straight back to him as I'd paid for a service.

He did say that he didn't want him back again.

Cheers.

 

[wilhelm]

12mil ? shouldnt that be 5mm? I aint going to van to get manual, ..... thats what I always look for, electrodes 3mm above snozel and 5mm top of snoz to diffuser..on a minor 1

Surely its b/f?, I cant remember a wm thermocon not being b/f.

im probably not paying attention

 

[Paffman]

12mil ? shouldnt that be 5mm? I aint going to van to get manual, ..... thats what I always look for, electrodes 3mm above snozel and 5mm top of snoz to diffuser.

Surely its b/f?, I cant remember a wm thermocon not being b/f.

im probably not paying attention

Yes I left is at 5mm, it was 12mm when I got there

FYI - he told me tonight he has had the combustion chamber cover off and looked at the baffles etc. Wonder if he fiddles?

Any other ideas?

 

[wilhelm]

I doubt if he fiddles with burner..........cos its a pain in the ar£e, as you know to take off.

well, if all the snoz siize correct etc and co2 I would double check electrodes, and maybe try new transformer? cos the sort is forming from somewhere.

hth.

 

[Paffman]

I doubt if he fiddles with burner..........cos its a pain in the ar£e, as you know to take off.

well, if all the snoz siize correct etc and co2 I would double check electrodes, and maybe try new transformer? cos the sort is forming from somewhere.

hth.

Have you been drinking

Can I have that again in English ?

 

[oilman]

Bottom baffle support burning is common. Over firing. May be not according to spec, but in practice they do. I fit 0.4 nozzles. You need to get a baffle with the support welded on to it, and then weld a 6mm strip on the edge of the baffle, or it falls through the hole.

You have to chisel the remains of the original support away, so the assembly drops in and wedges in the combustion chamber.

I know this works, I've done it, though GAH did not supply the bits so they fitted until I added the 6mm strip. You also have to grind away the strip on site for a correct fit.

I assume you checked the fuel filters.

 

[Paffman]

Yep, did do the filters, how would they cause this problem?

 

[oilman]

Blocked filters make for sooting boilers.

 

[Agile]

Blocked filters make for sooting boilers.

Can you explain that for us mainly gas men?

Surely a blocked filter would give a weak mixture and the opposite of sooting???

I would expect sooting would result from an over supply of oil, restricted air inlet OR recirculation of POC into the air intake ???

Tony

 

[oilman]

A blocked filter makes the vacuum developed by the oil pump, which is trying to suck the oil, rise to the extent where gas is drawn out of the oil. The gas/oil mixture gets pushed along to the nozzle and what should be a fine spray, turn into spitting lumps of oil.

You will have seen the effect when you have turned on a tap when there was air in the pipe, and instead of a smooth flow of water, out comes lumps, that splash all over the place.

These lumps of oil don't mix properly with the air and so you get incomplete combustion, and smoke.

I've seen filters so blocked, oil wouldn't flow through them under gravity, yet the pump could pull it through. Needless to say I was called out as the boiler was sooting.

 

[Paffman]

Just an update...

Went to this boiler again today, checked the flue, it had a plate fixed to the end (for wind/blowback problems?), the customer wanted to removed this and the flue came off in his hands. When I checked the seal that goes in the exhaust telescopic section it was in bits, allowing exhaust gases to enter the air intake. As the customer wanted heat now, I disconnected the snorkel from the burner, told him not to close the cupboard door (no vents in wall or door). One hoover bag of soot later the combustion chamber was as clean as I could get it, serviced burner fitted 0.4x80EH nozzle, PP 100psi and tried to set the CO2% at 10-11% as per Thermecon when I rang them.

When the burner was running you could smell the exhaust fumes and feel the heat coming down the air snorkel, no wonder the plastic intake on the burner was melted. So I blocked the snorkel off, but I could not get the CO2% above 9.4 with the air adjustment on 1.

Before when I adjusted the CO2% it was 11% at about 4.5 on the adjuster. The customer is so fed up with it he is going to replace the boiler instead of sorting the flue - suits me as it's a bu@@er to work on in a cupboard that have to step up into in an upstairs bathroom.

My question now is why could I not get the CO2% up to 10% ? I guess it was meant to run with the snorkel.

 

[Agile]

So was the sooting mostly as a result of the blocked filter or the recirculation of flue products?

As its only three years old it seems a very expensive solution to replace it.

Tony

 

[wilhelm]

Tony, I know a couple of WM thermecon owners, who have been put on suicide watch.