Baxi 80e Fan / Flue Fault

liamcaswell · 10 Jun 2007

Hi everyone,

Boiler was working fine Yesterday, but now has a permanent "Fan/Flue" fault. Never had any problems with this unit before.

1) I have checked the flue for blockages. It is clear.
2) The fan is activating and appears to have no problems.

Is this the faulty PCB problem?
Should I purchase a: 5112380 to replace the old model number.

Is there anything else I should check?

Any advice would be greatly appreciated.

gas4you · 10 Jun 2007

You need to check the fan aps is activating and for any blockages in the fan venturi and aps pipes. The aps is a safety device that checks the fan is running correctly before allowing the boiler to continue to ignition.

liamcaswell · 10 Jun 2007

hi gas4you. Thanks

I have checked the APS pipes. They are clear. The positive + pipe makes the microswitch in the APS click on and off.

Can you clarify, what the fan venturi is please. I've seen the word venturi a lot on the forums.

timmy74 · 10 Jun 2007

what does the boiler do, does it try to fire, does the fan cycle on and off..

i had one of these before and changed allsorts pcb, aps, fans etc and it was the restrictor ring in the flue... how do they work for yrs then start doing that eh

gas4you · 10 Jun 2007

The fan venturi is inside the fan assembly and is a very small pipe for want of a better description. Just because you cab hear the aps clicking does not mean it is doing its job properly. You need to test the aps electrical points with a multimeter to actually see if the current is passing when it has clicked.

liamcaswell · 10 Jun 2007

Ok,

The fan cycles on, the APS diapragm then activates but the fault then appears. I have put a multimeter against the APS. When the water comes on the water microswitch activates the boiler. A voltage can be read initially on the APS but then goes to 0 after a couple of seconds. This might be when the warning light appears.

Is the PCB cutting the power to the APS. Should it carry a constant voltage whilst the diapragm is depressed by the APS pipe.

gas4you · 10 Jun 2007

Does this aps have 3 contacts or 2. If it has 3 then there is common, normally closed and normally open. I always get the open and closed bit wrong!! but if there are 3 then common wll stay live and the other 2 will each be live alternatley when either aps has proved or fan is idle

liamcaswell · 10 Jun 2007

It has three, Black at the front, blue and brown underneath.

When the boiler is idle, there is no power at all registering in the APS. Only when the boiler starts up i.e. tap on, there is a flash of voltage.

baxpoti · 10 Jun 2007

hold rest for 10 seconds

If this doesn't work replace PCB

liamcaswell · 10 Jun 2007

hi baxpoti, is this a typical symptom of PCB failure? What makes you think it is not the APS?

From research, I've read that I need PCB: 5112380. Is this correct?

Baxmax · 10 Jun 2007

liamcaswell said:
hi baxpoti, is this a typical symptom of PCB failure? What makes you think it is not the APS?

From research, I've read that I need PCB: 5112380. Is this correct?

Because he is BAXPOTI

liamcaswell · 10 Jun 2007

hopefully there is a method to his madness

gas4you · 10 Jun 2007

If anyone knows he will, also if no power is getting to aps then fault appears before this

ChrisR · 10 Jun 2007

One signature feature of the stuffed pcb is that you get a very short pulse of power to the fan. Yours isn't doing that, so look harder elsewhere. Though you may as well buy a pcb, they don't last long

liamcaswell · 10 Jun 2007

I do get a pulse at the APS but no steady current. The fan appears to function as required.

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Baxi 80e Fan / Flue Fault

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