Ferroli 77 FF Boiler

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bobw1956

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Called to a boiler fault on the above boiler.

The problem is an air pressure problem.

I can only get the boiler to fire if I apply suction to the APS tube, whilst the combustion cover is off, I know that this boiler is positive pressure,
and will not work with the cover off in a normal situation.

If I replace the aps and replace the combustion cover,the boiler will not fire.
If I remove the flue assemble the boiler will fire

I,ve done all the following checks.
Removed fan and cleaned
fan is running at high speed (230v)
removed venturi Clean
Aps checked ok
Flue checked and cleaned
Case seals look ok
Air pressure control damper slides up and down freely
I have not checked the Fan inlet or outlet pressures,
or the flue outlet pressures.

I will be replacing the flue assembly seals tomorrow

Ferroli tech not very helpful.

Has anyone experienced this problem,if so how do I solve it.
 
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Boiler has a positive pressure chamber. You are messing with a killer here. Storngly suggest get someone who knows the boiler.

Good chance replacing flue assembly will be futile!!
 
--------------------------------------------------------------------------------
gasmanuk
"I fixed same problem by replacing APS tubes "

changed tube

DP
I know the dangers of this boiler.
Flue assembly seals.

Thanks for your inputs
 
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Why is the boiler regarded as a 'killer', whats the deal with a positive pressure combustion chamber and is that why it is a killer?



bobw1956 - your from my neck of the woods!! so i'm sure you will help me out on some of my questions ;)

and if you do.......Thanks.
 
Positive pressure boilers are killers because if the case leaks then POC are discharged into the room.

They should only be worked on by qualified people who fully understand them.

Tony
 
Agile - so are they pressurised by the fan pushing through the chamber, rather than the fan pulling the combustion gases out of the chamber and through the flue (like most boilers).

am i close :D :?:
 
Exactly!

I supposed to say well done for understanding but I will not!

I have very high standards and expect everyone to have the intelligence to understand simple aspects of their chosen career!

Tony
 
You make me laugh Agile :D

I'm logging off now - my heads starting to hurt, thanks again



I'll probably be dreaming about boilers tonight again :)
 
I rarely dream about old boilers although I do admit to dreaming about some of their owners once in a while!
 
Bobw - these can be really fussy about the alignment of the venturi/air tube ends. Try new venturi bits - coupla quid.
Maybe fan slow or aps drifted of course - needs a digital manometer.

bster, point is that positive pressure boilers pump up the case with air from outside.
Trouble is that the flue intake takes a proportion of flue outlet gas, so it isn't "air". If it burns badly then there's CO, so it burns worse. And if the case leaks you have CO in the room.
 
ChrisR
when you say alignment of the venturi.do you mean that the pin hole in the side, should be facing down,if so that is fussy.

When removing the venturi to check and clean,I may have misaligned the hole,when refitting,Iwill check that next visit.

Fan is clean, running at 230v with a very good flow of air,aps is new, wired correctly, 1=brown,2=black,3=blue,with the air pressure tube connected to P2 on aps.

Come on Ollski I know you now this boiler
 
for those who may want to know

the boiler is up and running

after changing the flue assembly seals

the seals don,t look that bad?
 
After EIGHT days ???

I am surprised if it was only the flue seals!

If Bster changes his profile to better show his location as being in S Wales then I will give him a tip on easily diagnosing this kind of fault!

Tony
 
D

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