Biasi M90e 24s Going onto lockout frequently

[Mcfly1000]

Hi folks I'm looking for some help and advice and this seemed to be the place to ask it.

I have a Biasi M90e 24S boiler that is 7 years old. It has been working fine until the last couple of months.

I'm not trying to 'do' anything with it myself, I'm an electrical engineer not a gas engineer, but I am on a Homecare contract with British gas, and after 5 visits they still haven't fixed my problem so I'm asking for pointers to give to the next bloke who turns up.

The problem is that at least a couple of times a day the boiler is operating normally, then when it tries to fire up as it does to maintain temperature when its on, it starts whirring, but no flame comes on, and after 10-15 seconds it drops onto lock out. If I reset it immediately it will do the same thing indefinitely, if I wait 20 mins It will come on again and either stay on, or come on with the timer until the next time it locks out.

I haven't really noticed any correlations between times of day and when it does it, other than it is slightly more frequent first thing in the morning when it is coming on with the timer, and it has been happening more in the past few days when it has been really cold.

The guys who have come so far, have replaced 2 temperature sensors, and dropped the operating capacity twice, once to 22k then to 19k. This hasn't fixed the problem, and to be honest has made it quite hard to warm the house up.

Also the second guy said my pressure at the meter was fine 20mbar but at the boiler it was low, so I should get a replacement 22mm pipe put in. Duely done that and it hasn't solved the problem either.

Since they were worried about the temperature and had replaced sensors and turned the boiler down I have been paying attention to that and on the gauge on the front it gets to a maximum of 60 degrees, but it can cut out at any temperature. Even from cold.

The only other thing I have noticed is that after the guys had come out and done their stuff, it worked for about a day and a half each time, before going back to locking out 2-3 times a day. (5-6 today)

Ok, so any advice gratefully received. I think I have covered everything I have noticed but if you need more information and its safe for me to get it please ask.

Hoping not to have to use more than one more day of annual leave staying in waiting for British gas, as I'm running out!

Thanks

 

[transam]

Must admit all of these Biasi model code no's do my head in However there are 3 service or fault finding lights on this model , I think ? that u can only see 1 on the front facia ? green light

The other 2 are visible if you remove the a panel were the power cable go's into the boiler ? assume u have a service manual ? if not download from there website ! which will show u how to access , it will also give u a list as to the light codes eg how all the leds light up/flash ect when the boiler locks out will or might indicate the fault ??

My guess is ign board ?? maybe ? possibly ?? than again ??

 

[weargas]

When you say it locks out, does the red light come on or does the green power light start to flash quickly?

 

[Agile]

The guys who have come so far, have replaced 2 temperature sensors, and dropped the operating capacity twice, once to 22k then to 19k. This hasn't fixed the problem, and to be honest has made it quite hard to warm the house up.

Thanks

That does not make any sense. I suspect you may mean output power but that would be in kW.

Unless you have a very large house then even the near minimum power of about 12kW would normally heat the house adequately.

I suspect your radiator sizes may be too small unless the boiler is only reaching 60 degrees. If its not then gas settings may not be correct. I would never assume anyone in BG would necessarily even know how to set them.

Without proper engineers measurement data its impossible for me to guess what may be wrong in your particular case.

You are welcome to ask your BG engineer to telephone me after 10am and if he is non abusive then I would be willing to try to help him but its really all down to the man on the spot to try to diagnose the problem and that requires diagnostic checks.

Tony[/b]

 

[Mcfly1000]

Hi folks, Thanks for trying to help.

transam - I did get a service manual, and felt confident enough that I wasn't getting near any gas bits to get the boiler into fault finding mode, then back to normal.

The lights that were flashing were indicating that it was the fault - Lack of burner ignition (No ignition signal from the full sequence ignition device)

weargas - Both the red light comes on, and the green light flashes 3-4 times a second.

Agile - Yes you are correct I meant output power. They dialed it down from 24kW to 22kW then to 19kW or so they told me. The house is a reasonably large 4bed with single glazed windows. I haven't done anything to the radiators, they always just worked fine, but I'm not sure how to tell if they are too small. It is only reaching 60(ish - its not that exact because the needle is quite big, call it 60 to 65) degree on the temp dial at the front... whether that is working or not, is I suspect your point about the need for a qualified person doing diagnostics onsite.

Thanks for your kind offer, but I wasn't wanting anyone to put themselves out on my behalf. if there are no pointers I can give to the engineer then I'll trust in his training... Though if this keeps going on for a few more visits, I might take you up on the offer...

 

[transam]

Assuming that the gas ign pressure is correct , burner ok lighting evenly .
detection probes never had to change any due to a fault ?
I suspect it is the ign board ?? think there are or were 2 makes of board on this model fitted at 1 time or another ? bertili & partners & a honeywelll variant I think ? ) If I am correct ? in my view the honeywell variant is the better board ? But than again ?

 

[Agile]

The gren light only flashes every four seconds when the boiler selector is in the off position.

A flame failure can be caused by many different things and its normal for an engineer to check them first and only then to wonder if the ignition circuit is faulty.

Its no problem for me to help a BG engineer over the telephone, I already get one or two a week so another would not matter.

Tony

 

[Slugbabydotcom]

it starts whirring, but no flame comes on, and after 10-15 seconds it drops onto lock out

sounds like a sticky air pressure switch to me
perhaps the fan is stiffening up a bit