Boiler not working properly Biasi M90 24 S.

This boiler was in a rented house in Watford way A41. The boiler is failling intermitently. Sometimes the boiler fails to light on central heating or hot water demand. The ignition sequence starts and stops just before sparking. ( No spark when boiler fails) Tenent said that every day the boiler works fine untill the radiators are fully wormed up. then the fault develop in the latter part of the day..and every day.. so the tenent had to play with the boiler to get any hot water.... So who are the candidates to be the faulty part of this Biasi gas boiler?..Over heat stat.. no if it is over heat stat the boiler will go to manual resetting mode?..what else.. temperature sensors?...could be...but Not convinced.......PCB?, electrodes, cables? air pressure switch? pump?....the candidates for the faulty part is growing bigger now.. Any way the faulty part was identified and repalced. the same day. Like usual it was not easy to find the Biasi part.. Part centre send me to Park Royal branch computer said YES but there was no actual stock.... ...It was only my determination to find the part and complete the job before the week end.. which finally paid off. The boiler is working fine now..but I recommended a boiler service asap due to non related reason.

[@unicuk]

Sorry Guys - the same fault can be related to many parts in the ignition sequence. So if I say change one particular part - it might not work for you.. and if the boiler does not work -- I will also get a bad press. Also if I start telling the general public which part is faulty , they may try to change the parts themselves and get into danger. In UK if you are not Gas Safe Registered .. You should not attend to repair your boiler. You must hire a Gas safe registered engineer to get it fixed. Otherwise you are not only putting your life at risk but also your family and neighbours.
So most of our Videos I am not telling exactly which part was actually faulty. For a Gas safe registered but still trainee engineers on boiler repairs the faulty part can be found by studying the ignition sequence and by pin pointing exactly when its failing . The part right at the time of failure is likely to be faulty hence need to be isolated and tested . if this intensive testing of the potential faulty part confirms that the part is actually faulty, then it need replacing.
Different Example - Lets say Ignition Sequence stops at the fan.. fan is coming but nothing else is happening.. potential faulty parts - 1 air pressure switch- 2 Fan ( fan pressure too low ) , 3. condensate in the pressure tubes - 4. blocked flue or 5 . PCB. now its time to check these 5 scenarios. Lets say fan coil resistance is normal , Bearings good, APS common goes from NO to NC when the fan turns, No squirrel nests in the flue and crystal clear pressure tubes, now have a closer look at the PCB and turn it over - If there is a dry joint on the PCB near the fan relay.. its highly likely to be faulty PCB then. There you have it.

[@ladystyl3]

Video and info very informative to my problem, but didnt state what the fault was and what part was required, which may have been helpful to me as i have allready tried variouse things so it didnt help me sort my problem afterall

[@joisephine]

I have the same problem and have no idea what to do. I have just had to call a boiler repair service, I'm a student and it's going to cost me £117 for the first hour! How did you resolve this?

[@truthseeker959]

Hi, so what was the actual part that was replaced please?

[@Silence975]

i have similar problem it fires up there is flow on the ch but the return is cold as all of the radiators is it anybody know what should i do ?

[@rolfen]

Is that water pump vibration noise normal? Is there any way to fix it? Mine is doing similar sound, with vibration that can rattle the case sometimes and it is bothersome because the boiler is in the room in which I sleep! Is there anything that can be done to reduce the water pump vibration noise?

[@unicuk]

Hi Rolfen,
This boiler is probably the worst boiler casing designer winner in the last 10 years. It has so many screws and bits in the case. Most of these boilers I have repaired is making vibration sound. Replacing pump may minimize the sound for a little time - but I guarantee it will come back to haunt you again. Also new pump installation can set you off by £ 300+ because to buy the original pump will cost odd £ 200. ( they sold the complete boiler in selco for only £ 450 some years ago now they cultivate their stock on the wall.. kinda blackmailing !)
So my advice to you is to get a new boiler and re-locate it to the kitchen if you can. There are good boilers such as Vaillant, Baxi group ( Main - Potterton - Baxi ) Ideal Logic and even Heatline Capriz plus is better than this what you have. Best Of Luck

[@rolfen]

***** Thanks a lot for your reply. Unfortunately I am renting and do not have the choice to displace the boiler :) I told my landlord about the sound, he sent someone (but I don't know how qualified they are) and that person said the boiler is working normally. In my old house, the boiler was in a kitchen closet and I never heard it, there was virtually no way to know if it was running or not, unless you paid very close attention to the noise. Anyway I feel better now because I was worried that there was something wrong with the boiler, and this is a little reassuring. I also have a CO detector right next to it, so I should be OK. I have minimized the vibration by sticking strong magnets on it, they hold the case somewhat together, but the noise is still a little bothersome because it's a little low frequency.
In any case, thanks a lot for your answer (and your videos as well, I watched many of them), it is much appreciated!

[@unicuk]

Legally the Landlord need to give you a copy of a valid Gas Safety certificate. You should ask him for a safety check and a certificate asap.

[@markcaswell-daniels5650]

Please let me know what needed replacing, my M90 has the same problem and no one seems able to fix it.

[@unicuk]

Sorry Mark - the same fault can be related to many parts in the ignition sequence. So if I say change one particular part - it might not work for you.. and if the boiler does not work -- I will also get a bad press. Also if I start telling the general public which part is faulty , they may try to change the parts themselves and get into danger. So most of our Videos I am not telling exactly which part was actually faulty. The faulty part can be found by studying the ignition sequence and by pin pointing exactly when its failing . The part right at the time of failure is likely to be faulty hence need to be isolated and tested . if this intensive testing of the potential faulty part confirms that the part is actually faulty, then it need replacing.
Different Example - Lets say Ignition Sequence stops at the fan.. fan is coming but nothing else is happening.. potential faulty parts - 1 air pressure switch- 2 Fan ( fan pressure too low ) , 3. condensate in the pressure tubes - 4. blocked flue or 5 . PCB. now its time to check these 5 scenarios. Lets say fan coil resistance is normal , Bearings good, APS common goes from NO to NC when the fan turns, No squirrel nests in the flue and crystal clear pressure tubes, now have a closer look at the PCB and turn it over - If there is a dry joint on the PCB near the fan relay.. its highly likely to be faulty PCB then. There you have it.

[@markcaswell-daniels5650]

Cheers, got it fixed a while ago! To your credit it was a faulty PCB

[@neily032]

they have two pcbs in these its prob the ignition pcb

[@ArksE8]

Flow switch

[@unicuk]

No - it wasn't the flow switch