Vaillant turbomax fault finding f33 fault code

[jhl747]

I currently have no central heating or water. After resetting the boiler I get an F33 fault code.
Any ideas please?

 

[holty]

f 33 Main heat exchanger anti freeze protection mode Check air pressure switch, fan, fan supply or flue.
(837/637 only) due to no switching signal from the air pressure switch system.

this is from MIs.

 

[holty]

basically can you here the fan running first.

 

[jhl747]

Thanks for that.
Anything simple/obvious that a novice can check........no chance of getting anyone out today I doubt!

 

[jhl747]

No can't here anything running first.
After reset sounds like boiler fires up then nothing again.
Green light on throughout!

 

[holty]

with them symptoms best to get someone out(gassafe).

 

[Agile]

f 33 Main heat exchanger anti freeze protection mode Check air pressure switch, fan, fan supply or flue.
(837/637 only) due to no switching signal from the air pressure switch system.

this is from MIs.

If thats the fault code cause then its the sensors to be checked and not the fan etc!

Tony

 

[holty]

that was copy and pasted from the MIs.agile!

 

[The831Bunny]

If the fan is running (listen/feel for air movement at flue terminal if possible) then more than likely to be a duff air pressure switch located top righthand side of boiler (outside of combustion chamber). If its the black Schroder version it will almost certainly be the problem. Give it a tap when the boiler starts up. It may work for a while.

I would advise a Gas Safe engineer changes this as the flue, fan and combustion chamber need to be disturbed/checked for a correct job. As its cold there may also be condense formed in the silicone tubes to the air pressure switch. This can prevent the APS from switching also. Again a job for a Gas Safe engineer.

Cheers

Bunny

 

[Agile]

f 33 Main heat exchanger anti freeze protection mode

this is from MIs.

I am not disputing that the MI say that.

However, how can the fan/APS create that fault code?

Isn't it generated as a result of sensors indicating a temperature below say 3°C ?

Tony

 

[jhl747]

Thanks to everyone!
It was in fact the fan being dirty that prevented enough airflow being sensed to trip the pressure switch.
JL

 

[Agile]

Glad to heat that its working again.

That makes me even more keen to hear the explanation from Bunny!

Tony

 

[holty]

If thats the fault code cause then its the sensors to be checked and not the fan etc!

Tony

 

[bmarashi]

hi i have the same problem can any body guide as to where i can find the fan please as it is really cold tonight

 

[bmarashi]

No can't here anything running first.
After reset sounds like boiler fires up then nothing again.
Green light on throughout!

hi jhl747 it seems these boilers are set on timer or weather sensative do you know here i can find the fan for this boiler so i could try and clean it my self please as it is getting desprate with no engineer willing to come