fume leak from around the blast head

[DAVHM]

Hi Guys,

I serviced my boiler (Worcester Dansmoor 15/19 CF/FL with Riello RDB1 burner) last month and everything got a clean bill of health. At least that was what I thought. When the burner is going full blast I have no problem. But when it stops (or when I switch off the boiler) I start getting serious fume smell.

What I think is happening is that when the boiler is switched off the fume inside the chamber — no longer driven up the flue by the air pump — lingers on in the fire chamber and then gradually leaks back out from around the blast head due to the poor seal. I believe the gap between the blast head and the hole in the boiler is too big (4 - 5 mm) to be sealed by a simple gasket currently fitted. So I am wondering how I could seal the burner head properly to stop the fume leak. I have used fireproof rope and also rubber rings in the past, but none of them were satisfactory. The guy who serviced the boiler used the gasket and was convinced that would do the job. But I now know that the gasket was a waste of time.

The boiler hole diameter is 89mm. The blast head on the Riello RDB1 is 85 (I think).

I would be very grateful for any suggestions.

Dave

 

[Best]

Hi Dave. You shouldn't have any fume smell at all. Clearly there is something wrong with the combustion and perhaps also a gap for the gases to escape. Carbon Monoxide is deadly. What are the Co2 and other analyser results in the last service? And when was it serviced last?
I note you say you are sealing the burner yourself. Don't touch it as you need to know what you are doing.
Do not use your boiler and get someone experienced to check it all immediately!

 

[Dotty]

Two words leapt out at me.....

"I serviced......."

Please get a competent person in. It's not a case of rubbing it round with a hoover and changing the nozzle.

How did you recommission it?

 

[Unregistered]

- it was serviced by a qualified engineer last week. Used his calibrated gauges and the co reading was 28ppm -- cod2 was 11%. Burns extremely well.
When it is going full blast the fume is forced up the flue, so no problems.
When the burner stops, the remaining fume in fire chamber leaks -- well it must leak as I get the smell.

I have not tinkered with the system and I won't, so no need to panic! I just want to hear from a clever expert what is the best way of sealing the gap between the blast head and the hole so that I can suggest it to the next guy I call in.

 

[Best]

It's worrying! Oil burners going really seriously bad will let out a lot of smoke and fumes from the burner the instant each time they turn off on cycle.
I think you have messed your boiler up and left it inefficient, probably making itself filthy and certainly highly dangerous and inoperable Dave.
It pays to get an engineer to service and set it up with an analyser. A boiler can appear to be okay, but can be using a lot more oil than it should.

 

[Dotty]

Ok. It was your wording that blipped our radars.

The next guy you call in will have the right stuff on his van, if he doesn't, or he doesn't know what to get then he shouldn't be touching oil either. Whereabouts are you?

And please log back in. There's a timeout on sessions for new users.

 

[Best]

- it was serviced by a qualified engineer last week. Used his calibrated gauges and the co reading was 28ppm -- cod2 was 11%. Burns extremely well.
When it is going full blast the fume is forced up the flue, so no problems.
When the burner stops, the remaining fume in fire chamber leaks -- well it must leak as I get the smell.

I have not tinkered with the system and I won't, so no need to panic! I just want to hear from a clever expert what is the best way of sealing the gap between the blast head and the hole so that I can suggest it to the next guy I call in.

Well you did say you were working on the burner seal and wanted to fix it.
There could be a problem with the combustion, as I already said. You need to get an engineer and just tell him you have fumes and that they are escaping. That's 2 faults that need investigated. No point in me saying what I think could be wrong as there are other possible faults and no use you starting to tamper with it all

 

[Unregistered]

Best, I am not getting any smoke or fume out of the burner. In fact it is in tiptop condition. It has been serviced regularly and cleaned and checked.

I know for a fact that the only problem is that the blast head is not a perfect fit to the boiler hole. And the gap needs to be sealed somehow or the fume is bound to leak back. Please read my original message again.

Dav

 

[Best]

You said you were getting "serious fume smell".
I would get the engineer that did it last week out again. Might be entirely his fault and if it is, he should fix it free. Just describe it to him on the phone and the boiler type.
A gasket could be damaged, but I still would have the combustion and nozzle and workmanship checked, - even if it had been my own previous work. Mistakes and faulty parts happen

 

[DAVHM]

Ok I am going to approach this query differently.

Question 1) what is the typical difference between the diameter of the blast head and the boiler hole?

Question 2) is the fume that comes out of the chimney smelly and harmful to breath?

Thanks in advance

Dave

 

[Best]

Question 1) what is the typical difference between the diameter of the blast head and the boiler hole?

Question 2) is the fume that comes out of the chimney smelly and harmful to breath?

Dave

(1) The boiler hole size is irrelevant if a flange is fitted. Some are a tight fit, most are much wider than blast tube.

(2) If the burner is set up wrong or other fault the flue gases are very smelly and harmful - and massive CO, which is an odourless killer part of the fumes and puts you unconscious until death.
If it is burning correctly the gases will still have a bit of a smell from oil boilers and will still be harmful to breathe as the flue gas will contain carbon dioxide, carbon monoxide and traces of other nasty stuff that the human body cannot use to breathe in.
After all, oil or gas or solid fuel boilers produce flames, - flames burn only with oxygen, - we breathe in air to absorb oxygen only.

Get yourself a CO alarm fitted near the boiler, after you get it fixed. Don't leave it as it is, or attempt a temporary fix yourself. Trust me, I have breathed in flue gases to my lungs from an incorrectly running oil boiler for just a second and it left me gasping for air.

 

[Dotty]

Closing this thread now, the appropriate advice has been given under no uncertain terms. And the follow on questions are concerning me.