I own a Baxi Barcelona and my bother purchased a Baxi 100 HE two months after me. I have had intermittment lock out problems and was told to clear the condensate trap (yellow plug under bottom right hand side of boiler) I got a lot of what looked liked black/grey silt or very fine sand out and about 1 cup of water, so place a jug under there when you are emptying it! This seemed to do the trick and I left mine at that.
This last week my brothers kept locking out and with 1 second flashing red led. Apparently it had started doing it more and more frequenly over the last 5 days, and would now lockout after only 20 minutes running.
He however had a detailed installation and comminsioning manual for his (one thing I never got with the Barcelona, the 100HE is mechanically the same but the electronic PCB in his is slightly different, get the 100HE commissioning guide from the baxi website under literature, www. baxi.co.uk) and on following the fault finding flow chart for this fault, it suggests that either of the thermostats (little black buttons with two electrical connections on them) or the thermistor (little red button) was at fault. I tested these and they seemed to be OK. We replace all three anyway, and still it would lockout after 20 minutes running.
To cut a long story short, it turned out to be the fan thermostat was actually getting too HOT and doing it's job correctly and locking out. The reason for the build up of heat in the air box was because the combustion box door seal had disintergrated in one corner allowing the very hot air into the air chamber, causing the safety themostat to trip. When we looked at the combustion door seal about 7cm in one corner was missing and the seal left in that area was crumbly and hard (not soft and spongy like the rest of the seal).
We bought a replacement seal kit and fitted it (cost about £5) and noticed that when fitting the seal in the bad corner, the original seal had been fitted about 4mm out of place allowing the hot air to escape and over time distroy the seal. (we could tell by the 'tide' mark of the old seal versus the marks from the combustion box that it had been fitted incorrectly.
The guide does not mention this could be a fault, just that you should take care to examine this seal as part of the annual service. We also serviced the boiler as per the instructions and even though it is 2 years old, it was very clean and only needed a small amount of hoovering. We did however, remove and clean the condensate trap as this had a good 3cm of slit in the bottom.
One thing we also noticed in the manual was that the boiler is supplied to only give a max heat ouptut of 75k BTU and if you want the full 100K BTU you have to remove the jumpers on the PCB. We have quite large houses with under floor heating and have know removed the jumpers and are getting much quicker cylinder heat up times.
Hope some of the above information helps, you with your problems. I am not a heating engineer, but with the installtion manual it took all of 1 hr to strip the boiler and give everything a clean and find the faults. So far then, I would buy another one if I needed to as ours run alot of the day, I have the Gas bills to prove it!!
