Biasi M96.28SM/C intermittent ignition fault after bleeding?

[nadimaj]

Full make and model: Biasi RIVA COMPACT HE M96.28SM/C

So, it appears that after bleeding the radiators in the loft (lots of air, far more than I imagined there to be!) we now have an intermittent apparent ignition fault with the boiler. The pressure gauge is sat at 1 as it always has been.

If there is no hot water demand (DHW or CH) for more than 15 mins chances are the boiler will fail to light up until the controls are played around with a couple of times. The annoying thing is that the operation light sequence cannot be found in the instruction manual.

We have from left to right:

------ I ------------- II ------------ III
Green flash --- Red flash ---- Steady green
---(NOT alternating)---

My brother in law who is an apprentice is coming around to take a look and has already advised a general clean but I fear it’s worse than that. As soon as I bled the radiators in the house, suddenly this problem.

Anyone?

 

[Rob]

The pressure gauge is sat at 1 as it always has been.

Considering it should go down when you take air out I'd suggest this is where you start looking.

 

[nadimaj]

Actually, it's probably more accurate to say that it went down a tiny bit (to about 0.9) but is now back up to 1

 

[transam]

Air pressure switch ( maybe ? probably ? if I remember correctly ?)

????????

 

[Agile]

Increase the pressure to 1.5 Bar.

That will chech the gauge is really operating.

I really dont understand why people love to bleed rads. It is the cause of so many problems!

Tony

 

[nadimaj]

My loft ones wouldn't heat up at all.

 

[nadimaj]

Latest is that I found the light fault code which is pointing at a 'Faulty Air Pressure Switch'. Done all the electrical contact checks and there does not appear to be any fault.

 

[Agile]

My loft ones wouldn't heat up at all.

Bleeing air out of them will make things worse!

You need pressure in your system to 1.5 bar.

Funny how you do other things but not what we advise!

Tony

 

[nadimaj]

Agile, with all due respect I have no idea what your talking about when you say bleeding a radiator will not help. In general situations, I have experience to say it most definitely does.

Anyway, so the diagnostic lights indicated a faulty Air Pressure Switch which was replaced, worked for about an hour and then gone again. NTCs were also replaced and the complete system drained and refilled. Everything in prestine condition, not even a smidgeon of grease to be seen.

As we have a case of a PCB reporting a fault with the Air Pressure Switch (when it's clearly not), what are the odds that the PCB itself has a fault?

Again, the fault is intermittent.

 

[Agile]

Agile, with all due respect I have no idea what your talking about when you say bleeding a radiator will not help. In general situations, I have experience to say it most definitely does.

I repair boilers and I can assure you that the only fault that bleeding radiators will cure is when there is air at the top and the top of the rad is cold. That is the ONLY reason that a rad should ever be bled.

In every other case bleeding rads will NOT help. It often will create further pressurisation problems. Many even bleed rads when they dont even know how to repressurise the system.

Nor will draining and refilling unless the system water is dirty. Doing that creates a risk of airlock problems and the air introduced creates more oxidation of the steel. Many dont remember/bother to add inhibitor after refilling!

You seem to have been blindly changing parts without consideration of what the fault really is! Nor should the combustion chamber have been opened by a DIYer.

The APS is easily tested but virtually never fail on that model. Its almost always caused by a faulty PCB and that can be a permanent fault condition or in some cases intermittent.

If intermittent then some people choose to live with it in view of the high cost of the PCB which also has to be replaced very carefully to avoid damage to the new one.

Tony Glazier

 

[nadimaj]

...the only fault that bleeding radiators will cure is when there is air at the top and the top of the rad is cold. That is the ONLY reason that a rad should ever be bled.

And that was exactly the problem I had!

A bit late, but thought I'd update all, in the end it was a faulty PCB. Replaced it after wasting time replacing the NTCs and Air Pressure switch. I know it sounds odd but the fact remains that the fault developed immediately after the above mentioned radiator bleeding (the morning after). Of course, just a major coincidence.

Faulty PCBs on these Biasi's are common I'm lead to believe.