Baxi 105e - flue problem ?

[Dave....]

Hi
All I wonder if you can help me- I had a plumber in to move my Baxi instant two foot,which was done a week ago, it now seems to have developed a problem but the fitter is now off work and is likely to be off for some time due to an accident.
I was hoping this may be something I could rectify in the meantime without having to pay for it again.
Following the units relocation it started cutting out the day after indicating with the first flashing led it cut out more and more until it wouldn't stay on at all.
I looked at it too see if anything was obvious and noticed a lot of dust on the burner, I removed the panels and vacumed all the parts put the panels back on inadvertently tested it the viewing glass off, everything seemed to be fine so I switched off and put it completely back together thinking I had cured the problem, however when I restarted it the same thing happened, realising this is something that is affected when the unit if fully rebuilt, I tested it by first taking the front panel off and tested (as expected) no change- so I removed the viewing window and found the unit ran but the flames were noisy, also I could hear air being drawn through the window, as suspected the burner died when it was replaced.
My assessment is that the unit is being starved of Oxygen, I confirmed this by replacing the glass and loosening the collar on the flue liner, this lets air in and also allows the boiler to run correctly.
When the unit cuts out the first led light flashes showing flame failure- it doesnt indicate a blocked flue - but if the liner was blocked I suspect the unit wouldn't detect this. of course we cannot run this now so its kettles for hot water- but in the meantime could someone please advise if this seems to be the right direction- could the liner be blocked somehow.
Dave

 

[baxpoti]

Disconnect the flue on top of the boiler and run the boiler briefly.
Does it work with the flue disconnected?

 

[Dave....]

Hi Baxpoti
I loosened the outer liner and it ran fine, but I didn't disconnect the actual inner flue, do you mean the inner flue or have I answered your question ?
Dave

 

[nickso]

its more likely that the inner flue is incomplete in some way after he moved it. take the elbow off or go outside if you can and inspect the flue through the terminal for any sections that may be out of place. this will also confirm any blockages.

by allowing air in at the elbow you have proven the boiler can run properly.

did he add any sections into the flue?

 

[gas4you]

Has inner flue dropped out of retainer so it is laying on the outside edge of flue? Could be breathing in its own fumes if so and locking out!

 

[Dave....]

Hi again
Thanks for the response chaps- to be honest he was struggling with the flue as he needed me to help with the connection on the boiler at one point while he was in the attic struggling with connecting an elbow- (as the inner kept swivelling I presume the liner is on a pivot ?) the space up there is very limited where the flue passes through from ceiling to roof so it will have been a struggle for a big bloke.

Yes he did add a bend and I remember him saying if it was much longer he wouldn't be allowed to put the bend in as a bend equals a meter (or something like that) the overall length is a meter off to its limit apparently.
I'll go up in the attic tonight and take the bend off and make sure the connection has been made correctly.

Thanks a lot for your advice, I'll let you know what the result is tomorrow.
Dave

 

[namsag]

Did you have a standard flue on boiler before alteration.. If so check that the restrictor ring has been removed . this is on the spigot on top of the boiler.

 

[Dave....]

Hi Namsag

no the flue went up through the roof anyway, he just told me it would be cheaper to bend the flue and use the exsisting exit rather than start moving slates on the roof and also the new position meant it would have to go round a huge 2 x 1 ft beam and there would be a bend in it anyway.
There is a hole in the top of the boiler and also an outer ring which lines up to the full width of the liner, so I presume this means it has been removed.
Dave

 

[Agile]

Although he seems to have been aware of the limitation on the effective flue length I am wondering if the permissable length has been exceeded.

I am not familiar with the parameters of your particular model but most similar boilers have a MAXIMUM effective length of under 3 m and thats with each elbow ( ignoring one on top of the boiler ) being 0.9 m.

If you have a vertical flue then many boilers require all flue to be in a larger size of 125 mm rather than the standard horizontal size of 100 mm.

Can you advise the total length, number of elbows and type of terminal? then somebody will compare that will the manufacturer's instructions.

Tony

 

[Dave....]

Thanks Tony
Ok I will have a look tonight an measure it all, I do know the flue is well above 100 mm so it will be 125mm, also the flue has no bend out of the boiler it starts off straight.
I will get back tomorrow and Thanks
Dave

 

[Agile]

Most 125 mm vertical systems alloy about 5-6m effective length.

Tony

 

[baxpoti]

If so check that the restrictor ring has been removed.

Has it been removed?

 

[Dave....]

Ok well this can't be more than 5-6 mtrs even with the bends so I will check 1/ the restrictor ring and also 2/ that the flue is connected correctly all the way up and as I said I will measure the diameter and the length of the flue.
Cheers Guys

 

[baxpoti]

105e maximum equivilant concentric flue length is 4m!

90° bends counts as 1m!

Your flue is too long!

Refer to page 17 of the M.I.

It should be switched off and the flue problem rectified.

 

[Dave....]

Hi
No I didn't say it was 5 os 6 meters long I said it can't be- it might be two and a half- it is already switthed off as it won't run.
Dave