BIASI Garda M90F32S Intermittent Lockout

[GoodDIYjob]

This started playing up 5 days ago and for the first time since we have lived here (3 years), showed the red light on the front panel and lockout active.

The pump would run but boiler wouldn’t light. I tried resetting twice, but it went to lock out shortly after the fan spun up.

I looked at it again in the following morning and added a bit of pressure to the CH circuit. It fired and operated ok. I called an engineer and he looked at it, didn’t diagnose anything else except the pressure guage seemed to be stuck or very slow to respond he cleaned the line to that out so it appeared to display a more correct pressure and he assumed the pressure had dropped too low and that is why the central heating locked out.

The water in the boiler is treated with F1 and was clear on draining but it is an old system now and all the radiators are past their best but work ok. However, they would be replaced when the time comes for a boiler change.

Yesterday, morning I woke to the boiler pump running and demand for heating being called from our programmable stat but no boiler heat. The red light and lockout was on again and the green operation light rapidly flashing. I tried to take the PCB cover off but isolated the boiler before doing so and the code was cleared when I turned back on.

I reset and the boiler, it re-lighted on 1st attempt and has remained operating normally for the last 2 days again. However, it seems to have an intermittent fault, could it or is it likely to be the primary flow sensor?

One thing that was strange on relighting after lock out was that the flame went out momentarily then immediately relit. I’ve never seen it do that before.

I’ll call the heating engineer again but wondering if I can help steer him in a direction with any experienced helpers here.


Thanks

 

[GoodDIYjob]

OK it just locked out again. Solid red middle light. Flashing greens either side. The visible operating light was also rapidly flashing before moving the dip switch.

This fault indication does not appear to be consistent as just turned bathroom tap on and it caused the lockout to trip but green operating light wash just flashing slowly normally and no diagnostic lights showing.

Maybe the DHW flow switch int. then?

 

[GoodDIYjob]

Any takers?

Just to recap, in brief.

Boiler locking out with red lock out light showing.

Can happen in CH or DHW demand.

Sometimes shows rapidly flashing operation light and fault code solid middle red, with two greens flashing.

However, sometimes just the lockout operates without the other LEDs.

The other thing that seems abnormal is sometimes on igniting the burner lights for a few seconds, then extinguishes then immediately relights but this doesn't seem to immediately trip lockout.

 

[Agile]

If your engineer needs "steering" then I would suggest that you need another one that is capable of steering himself.

I don't know what you mean by "operation light".

You mention a dip switch, which one did you operate and why?

Does your boiler have a single PCB or two?

The single PCB covers usually have a raised lump in the middle of the top with a screwed cover. Two PCBs have no lump.

Normally you would only have the red light on by itself if it has locked out and then you have moved the right knob to the left "off" position but even then the left green would flash once every four seconds!

Tony

 

[GoodDIYjob]

Operation light - I mean the only green led visible from the front of the boiler without removing the cover. Blinks about once a second in normal operation when boiler on and much faster when a fault is present.

Had to operate the dip switch to show the fault Leds and that is what the manual says to do. I operated furthest to the right, no 4 I think then returning to its original position.

Sometimes the red lockout is coming on alone, sometimes with rapid flashing from what I call the operation light as described above.

Unfortunately, I find with boilers and some other engineering type repairs some steering seems to be required if you want to get the problem solved and moving onto another engineer doesn't always improve things, it can make them worse!

There isn't a huge knowledge base for Biasi when you call engineers but you are probably aware of that!!

Edit. Ps it is a split board. The full sequence device is the NON honeywell one. I can't remember the name without looking at the manual. The underside of this board looked ok as far as a visible inspection goes.

Thanks

 

[Agile]

Best to call the operation light as the left green light.

You can drill 2 mm holes through the plastic and then see all lights. Moving one of the jumpers behind the DIPs will then give you constant indication of the boiler operation. Later boilers came with three holes.

There can be many causes of intermittent lockouts and most of them are gas related which we don't give DIY advice about here.

If its none of the other causes then its often the ignition PCB. These are either Honeywell or Bertorelli. They are both interchangeable although there are some very slight differences in their operation but these will not be seen by users of the boilers, only by engineers testing them.

Tony

 

[GoodDIYjob]

OK thanks Tony.

Engineer has been and checked gas pressure, cleaned electrodes but couldn't find any certain cause. It did flame out once while he was [here] but relit without locking out. He suggested ordering new electrodes both detection and ignition, one looked a bit corroded and also ordering a new ignition PCB as well to cover all bases.

 

[Agile]

There is normally no need to replace ignition electrodes on that model.

The ignition PCB is a common cause of intermittent lockouts.

Sometimes they are caused by dry solder joints and often they can be seen. But NOT anything connected with the discoloured areas as they are normal. Other times its caused by faulty relay contacts which are not visible.

Tony

 

[GoodDIYjob]

Just to close off...

I didn't really have that much of a say in the end as to what they replaced, but electrodes and ignition pcb seems to have done the job. Based on what you said, it probably was the pcb rather than electrodes. It (the pcb) didn't look visibly problematic, but also like you say, relays and component functionality can't be revealed by looking at it!

Engineer also cleaned out the "fly graveyard" beneath the burner. There must have been well over 50 underneath! Must have come in through the flue over the last who knows how many years. The boiler is ~10 years. Goes to show, that even though I've had the boiler serviced, for the last 3 years, nobody cleans in the combustion chamber or perhaps even takes the combustion cover off. And I haven't been using BG for the last 3 times!

Thanks for the advice and help

 

[Agile]

I would always hope that any service would involve opening that combustion chamber and removing any flies.

They don't do much harm but the main purpose is to look for any water leaks and check the fan turns freely.

Tony