As I mentioned above, some time ago, I had this boiler at that time ... and still have it. I haven't taken the plunge and replaced it despite it dating back to 1996.
I might be repeating myself but mine kettled in the early days of my tenure (I moved in to this place16 years ago) and in those 16 years I've had to replace a few things (fan, gas valve, air pressure switch, and have had a couple new three way valves in the cylinder cupboard)..... but the thing that stopped it kettling was the repeated draining of the water in the radiator cicuit and refilling with proprietary cleaning treatments. Did that several times and have since kept the water generously topped up with stuff to keep the system in good order and there hasn't been a hint of kettling for years. For the first few years I used Sentinel cleaner and inhibitor products but for the past nine years I've used Calmag/Calchem three in one treatment from Toolstation. it's less than a tenner per litre and I've used five litres in nine years (and have another litre waiting to go in at some point this year).
The previous owner did nothing to the system and as a result it was gunged up with black stuff in the rads and with a blocked pipe upstairs which caused the a phenomenom called "pumping over" wherin hot water is pumped into the expansion tank in the loft (and you see hot water coming from the overflow). I had the blockage sorted (by removing a section of blocked copper pipe) and a minor re-routing of pipe to prevent it re-occurring - plus, of course, a thorough cleaning of the system (all the rads removed and flushed through.
Another long explanation which you may or may not find useful .....
I might be repeating myself but mine kettled in the early days of my tenure (I moved in to this place16 years ago) and in those 16 years I've had to replace a few things (fan, gas valve, air pressure switch, and have had a couple new three way valves in the cylinder cupboard)..... but the thing that stopped it kettling was the repeated draining of the water in the radiator cicuit and refilling with proprietary cleaning treatments. Did that several times and have since kept the water generously topped up with stuff to keep the system in good order and there hasn't been a hint of kettling for years. For the first few years I used Sentinel cleaner and inhibitor products but for the past nine years I've used Calmag/Calchem three in one treatment from Toolstation. it's less than a tenner per litre and I've used five litres in nine years (and have another litre waiting to go in at some point this year).
The previous owner did nothing to the system and as a result it was gunged up with black stuff in the rads and with a blocked pipe upstairs which caused the a phenomenom called "pumping over" wherin hot water is pumped into the expansion tank in the loft (and you see hot water coming from the overflow). I had the blockage sorted (by removing a section of blocked copper pipe) and a minor re-routing of pipe to prevent it re-occurring - plus, of course, a thorough cleaning of the system (all the rads removed and flushed through.
Another long explanation which you may or may not find useful .....
