Just a simple thermistor off fleabay. had a couple of cowboys, (sorry heating engineers) look at it and one mentioned the ECU board and flame detectors and ignition triggers and gas pressure regulators and potentiometers blah blah blah but said he could put a new boiler in for £2.5k..... the other cowboy (sorry heating engineer) basically condemned the boiler by basically looking at it through the letter box whilst still standing at the end of the drive whilst taking a large inhale of breath through gritted teeth and holding his chin and saying " 20 year old ferrolli! Ha ha these were (human excrement) when they were new mate haha, you can't get the bits anyway mate haha, it's not worth spending any money on it mate it's ( fish hooked) but I can put you a new boiler in sometime in Jan for about £2k haha"
Having been a firm believer of doing any job myself if I can since about the age of six, I thought about it logically... the boiler when cold, fires up OK, heats the rads then the burner turns off normally when up to temp and the pump still pumps the water around until it starts getting slightly cooler again and it SHOULD put the burner on again to repeat the 'cycle', it wasn't, it would fire up but then after 5 seconds turn the burner off, then turn off completely, then after 5 mins try again but turn off, it did however seem to get the rads about 50% up to temp simply by just repeating 5 second bursts of flame for a few hours until I turned it off before it knackered itself completely.
Stone cold the next day it would behave itself until it came to the second 'cycle' then play up until I got fed up and turned it off. What dawned on me was it was temperature related. My last job was an engineer for aesthetic laser machines (these machines had a cooling/heating system in them that accurately controlled the temperature of the laser head for optimum power, basically a mini central heating system, changing thermistors on these was a regular occurance due to failure)
A quick look online searching for the boilers problem resulted in a few threads confirming thermistors on this particular model we're troublesome so putting two and two together I got one off fleabay.
On my boiler there are two thermistors, one for hot water return and one for central heating feed, post burner. the one for central heating was ideally situated OUTSIDE of the boiler underneath so it really was a 30 second job.by the most incredible stroke of luck in the curry house I bumped into a guy I worked with at the car dealerships 25 years previously, we got chatting, his son was now a gas engineer! What! Would he pop round my house to put a thermistor in for me? You bet your bottom dollar he could! He turned up and swapped them over in about 2 mins, new one in and its working perfectly, in fact I had to turn it down yesterday I was so warm.
easy fix but it is a 20 year old ferrolli consisting of a burner, a pump, a single control board and a few sensors so not exactly rocket science. So if you need any help with your ferrolli modena 102 I'm your man
Cost =£3.50 for the thermistor and a few pints for my ex colleague next time I'm in the curry house.