Ariston micro GENUS 27 MFFI problem

[billm]

The boiler in my house is about 4 years old and over the past 12 months has been tripping out every few months with the Ignition Failure (lockout) (red) LED coming on along with the Fume Sensor (yellow) LED.

In the past I have left it switched off over night and then it has sorted itself out when I switched it back on after pressing the Reset button. And it has always coincided with heavy rainfall or winds.

Until now. The 2 LEDS are always on and leaving it / resetting it doesn't change things. I think the pilot light is out and there is no "motor" noise which normally happends when I switch it on/reset it. Its just "dead" and then the 2 LEDS come on.

Now when it was first installed, it went wrong a few weeks later I think with the same problem. The engineer said that the outside flue had been fitted at a slight up angle and if it rained heavy some of the rain could go down the flue, which is pointed 90deg to the boiler, and sit in the bottom of the Fan. If this happened he showed me how to get rid of it by blowing down the Vent from the top access bung of the boiler which would clear any water from the bottom of the Fan. And it worked.

Until now. Done that and it makes no difference. Which is strange as we've had a lot of rain these past 48 hours.

I've taken the covers off the boiler and can see where that top vent pipe connects to the Fan. Next to it and connected to the Fan via a plastic pipe is an plastic Air Pressure Switch which I am guessing is comparing the air pressure inside the Fan with the ambient pressure on the spare inlet to the switch. Assuming again that if there is a difference in pressure then the switch doesnt switch. There are 2 red wires on the switch which look to to be going to the main PCB. If the Switch is working normally, are those red wires effectively connected together by the switch ? ie; If I were to connect them together that would bypass the Air Pressure Switch temporarily to see if the Switch had failed ?

Failing that, is there anything else I can check before calling a boiler engineer out ?

I have the boiler manual / fault diagnostic chart etc if that helps

thanks

 

[spacethegas]

call a qualified corgi.

the aps is a safety device & you really shouldn't play with it.

don't start bridging it.

 

[billm]

I think the APS is working. It clicks when one inlet has +ve pressure and again when the other has -ve pressure.

When you press the Reset switch on the boiler, is the fan supposed to turn and create a bit of air pressure which the Air Pressure Switch monitors ?

 

[BOB D.O.L.E]

[quote="billm";p="1021539" is the fan supposed to turn and create a bit of air pressure which the Air Pressure Switch monitors ?[/quote]


yes. this then sends a live feed to pcb then from there to spark + ignition
flame senser then proves and main gas valve opens

 

[mickyg]

Now when it was first installed, it went wrong a few weeks later I think with the same problem. The engineer said that the outside flue had been fitted at a slight up angle and if it rained heavy some of the rain could go down the flue, which is pointed 90deg to the boiler, and sit in the bottom of the Fan. If this happened he showed me how to get rid of it by blowing down the Vent from the top access bung of the boiler which would clear any water from the bottom of the Fan. And it worked.

That was very helpful of him to point that out. Why was it fitted like this??

 

[billm]

yes. this then sends a live feed to pcb then from there to spark + ignition flame senser then proves and main gas valve opens

The fan is free to turn but does nothing when I press the Reset button. So either the fan motor is kaput or the feed to the motor is missing. I assume there is a relay or PCB or both in the feed circuit. I will check if there is voltage being applied to the motor and press Reset and go from there

If there is no voltage at the motor terminals when I press Reset is there likely to be a relay in the circuit or is it fed directly from the PCB ?

That was very helpful of him to point that out. Why was it fitted like this??

it was a plumber that put the CH system in and it was the Ariston service bloke, whi repaired it when it failed a few months later, who told me the plumber had installed it with a slight upward angle on the flue pipe. So by that time it was too late to correct the flue pipe angle

 

[spacethegas]

by that time it was too late to correct the flue pipe angle

no it wasn't.

should have got it done.

 

[billm]

Sorted.

I disconnected the Fan motor wires and applied 240v directly to the motor to test it. The motor spun OK and I think at the same time it also cleared out anything lying around in the fan housing that was affecting the APS from working correctly.

Then I tried the boiler and it reset and worked partially, ie; it fired up.

So then I reconnected the fan motor wires and tried it all again and it works.

Think I'll either try to buy a partial "shield" to fit around the cowl to stop rain getting into the fan housing or hammer the bricks out and re-set the vent cowl horizontal (or even slightly down)

 

[Agile]

Think I'll either try to buy a partial "shield" to fit around the cowl to stop rain getting into the fan housing or hammer the bricks out and re-set the vent cowl horizontal (or even slightly down)

Dont do that, it could be dangerous!

The proper solution is to set the flue angle to the correct slope which is about 3° downwards.

It sounds as if the "plumber" who fitted the boiler is not CORGI registered. In that case report him to CORGI and they will get him to correct it at no cost to you if he is registered or repremand him if he is not.

Tony

 

[billm]

Dont do that, it could be dangerous!

The proper solution is to set the flue angle to the correct slope which is about 3° downwards.

It sounds as if the "plumber" who fitted the boiler is not CORGI registered. In that case report him to CORGI and they will get him to correct it at no cost to you if he is registered or repremand him if he is not.

Tony

Thanks Tony. I have hammered out the brickwork and reset the flue so that it now has a slight downward slope. So hopefully any rain will now not go into the fan enclosure.

As for the plumber, he's long gone, years ago, prolly fitting double glazing (badly) now or banged up someplace !