Flue causing oil boiler problems.

[midas]

Hi
My misfiring boiler has been diagnosed as a faulty flue drawing in exhaust gasses causing it to cut out and reignite regularly.

It's now running but only because the heating engineer upped the oxygen intake which is apparently OK only as a temporary solution whilst we try and get a new flue.
My boiler is a Grant (Worcester) Boulter Camray Quartet 90/110 and although I found this:
http://www.plumbarena.co.uk/product...quartet-75mm-low-level-flue-kit/#.Uk2CL4ZJMs1

my heating engineer spoke to the manufacturers and they told him the part is no longer available so I'm guessing it's not the right one.

So basically what are my options apart from getting a new boiler?
Can flues be repaired? Or can they me made to order or adapted from a similar one? Or is there a breakers yard for boliers / flues !

Thanks for any help.

 

[Boilerman2]

The part listed looks to be correct, but as we all know Tinternet suppliers are great at advertising parts that they don't have a hope in hell of providing, - worth a try though!

BUT 1st - has anyone tried removing the existing flue system and rebuilding it with new sealings - I believe all the joints on the Camray 4 are simply taped up, so it might just be a csae of new taping on the inner flue joints!

 

[midas]

The part listed looks to be correct, but as we all know Tinternet suppliers are great at advertising parts that they don't have a hope in hell of providing, - worth a try though!

BUT 1st - has anyone tried removing the existing flue system and rebuilding it with new sealings - I believe all the joints on the Camray 4 are simply taped up, so it might just be a csae of new taping on the inner flue joints!

My engineer is coming back to try and do that as he seemed unable to source a replacement part so hopefully that will suffice, I was just thinking more long term really.

I'll report back after he comes on Wednesday.

Thanks

 

[dcawkwell]

My first suggestion is get another engineer.
He's talking nonsense. Or unblock the flue

Most likely cause is your solenoid valve or coil is playing up.
How many years has the boiler been in and working fine?

 

[midas]

My first suggestion is get another engineer.
He's talking nonsense. Or unblock the flue

Most likely cause is your solenoid valve or coil is playing up.
How many years has the boiler been in and working fine?

Boiler is probably 18 years old and I have had issues with the flue before about 5 years ago where it broke and had to be rewelded and sealed.
Generally worked fine until last month when it started to cut out.
Engineer showed me that when you put the case back on the boiler cuts which he said was a sign of flue gases getting back in to the boiler.
He showed me the co2 reading both with and without the front casing on and they were higher with it on.

 

[slapper]

My first suggestion is get another engineer.
He's talking nonsense. Or unblock the flue

Most likely cause is your solenoid valve or coil is playing up.
How many years has the boiler been in and working fine?

Boiler is probably 18 years old and I have had issues with the flue before about 5 years ago where it broke and had to be rewelded and sealed.
Generally worked fine until last month when it started to cut out.
Engineer showed me that when you put the case back on the boiler cuts which he said was a sign of flue gases getting back in to the boiler.
He showed me the co2 reading both with and without the front casing on and they were higher with it on.

Your Engineer is correct its called ingestion, leaving the case off just allows more oxygen to the Burner, wont hurt the boiler but wont be as efficient.

 

[oilhead]

[quote="dcawkwell";p="2900050

Your Engineer is correct its called ingestion, leaving the case off just allows more oxygen to the Burner, wont hurt the boiler but wont be as efficient.

Check the seal round the baffle access cover before drastic action. With only two nuts holding it on it often leaks.
Judicious use of a FGA will pinpoint any leaks round any joints enabling the full cause to be identified.

 

[Terrywookfit]

This was a common problem with this boiler even when fairly new.
Providing that the inner flue is not corroded. Sealing the inner flue joints with a high temperature silicone makes a suitable and long lasting seal.

 

[midas]

Many thanks to all who replied. If my heating engineer doesn't mention your suggestions I shall prompt!
Hopefully a good inspection and decent reseal will do the trick.

I shall report back.

Thanks

 

[midas]

Your Engineer is correct its called ingestion, leaving the case off just allows more oxygen to the Burner, wont hurt the boiler but wont be as efficient.[/quote]

Unfortunately my engineer is ill so hasn't returned yet but the boiler is running fine (with the case ON) but only because he tinkered with it somehow to increase the oxygen level or something like that I think.

He said long term that's not ideal as the boiler runs hotter and can affect the baffles. is that correct?

Thanks

 

[Burnerman]

He's just opened the burner air door to allow more oxygen in.....normally this would cause overfiring which eventually would goose the baffles.
No need to panic about it - just get it seen to soon.
John

 

[midas]

He's just opened the burner air door to allow more oxygen in.....normally this would cause overfiring which eventually would goose the baffles.
No need to panic about it - just get it seen to soon.
John

What is overfiring? Is that the same as short cycling?
Maybe it's my imagination but would my described problem and temporary fix cause my boiler to fire up and switch off more than normal?

 

[Burnerman]

Overfiring is basically when the flame from the burner is too large.....this can cause the flame to impinge on the back of the fire box / heat exchanger, which may cause local boiling of the water within.
Also the baffles, which slow the speed of the combustion gases down, allowing more heat to penetrate the heat exchanger can get too hot and they simply burn away to rust.
Overfiring within the boiler fire box is likely to increase the temperature quicky and dramatically and presumably is helping to cause the more frequent cycling.
John

 

[midas]

Overfiring is basically when the flame from the burner is too large.....this can cause the flame to impinge on the back of the fire box / heat exchanger, which may cause local boiling of the water within.
Also the baffles, which slow the speed of the combustion gases down, allowing more heat to penetrate the heat exchanger can get too hot and they simply burn away to rust.
Overfiring within the boiler fire box is likely to increase the temperature quicky and dramatically and presumably is helping to cause the more frequent cycling.
John

Thanks for that. How can I identify more frequent cycling rather that it just being my imagination / paranoia!?

 

[Terrywookfit]

Another point to mention is that the excess combustion air will raise the FGT and make the seals worse. You are basically trying to warm the garden up.