Even though I am not a Baxi qualified engineer (so please don't take my word for what follows) I feel it my duty to post a reply as when I was in the pit of despair with my Baxi this forum helped a lot.
I had a boiler which;
1) Started making a noise on start up audible three streets away
2) then developed a drip from the casing
3) then refused to stay on even though the ignition was lighting the gas
I assumed the noise was normal and the leak was from the condensate overflow, which was pretty full of grey gunk. More of this later!
As I had no heat at all I downloaded the manual which told me to check the thermostat and the cut outs (little red and black jobs stuck on to the outlet pipe and inlet air vent. These were fine.
The manual also suggested checking for an open circuit from the dry flow monitor switch - a device which cuts off the gas when there is no flow through the boiler either because the boiler is dry or because all the thermostatic rad valves are shut. (It is located at the exit point from the combustion box and connects to the curved outlet pipe) If the switch is open circuit it advised changing the PCB (the expensive last resort - I spent two solid days just before the last cold snap desperately looking for a heating supply shop with one in stock- luckily unsuccessful as the pcbs were fine)
Anyway, I was about to give up and buy a load of logs when I though I'd try simulating a dry flow fault by short circuiting the switch - lo and behold the boiler fired up and stayed up (thus achieving hero status domestically)
As I understand the manual, the logic was reversed - open circuit bad, short circuit good being the way it worked in practice. It may be a difference between the Barcelona and the 100he but it is a little perverse to change the logic (if I am right).
Flushed with success I thought I'd try to sort the noise and leak. To cut a long story short, the root cause was a defective seal on the combustion chamber which was letting gas out into the boiler casing. This gas was condensing causing the leak and upsetting the airflow leading to the noise.
A temporary roll of aluminium foil replacing the draught excluder type seal cured both problems pro tem while I ordered the proper kit.
So my advice is check the seals on the combstion chamber regularly - I think the basic design is good but let down by some components which are not up to the job.
pip pip
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