No, this isn’t a diatribe about “her indoors”, it is about boilers of the heating variety.
I can remember a visit to Beamish museum in its early days, probably in the late 70s. In amongst the arcana was a rather rusty remnant of a locomotive boiler with a large hole in the side. The twisted metal round the hole along with the distortion of the boiler tubes within suggested that when it failed it did so very spectacularly. I have a photo of it somewhere but not readily to hand. I’ve always had a healthy respect for the latent power within the steam engine ever since the days of my Mamod models powered by purple, strange smelling methylated spirits (although it has to be said that those little models weren’t particularly powerful, beyond making their flywheel spin).
Now domestic boilers generally don’t boil as such, they simply heat water for circulation around the radiators and may have a calorifier coil to transfer heat into a lagged tank for domestic hot water purposes. Our current house boiler is an Ideal Standard which our tame gas man tells us is an excellent boiler and pretty reliable but they typically last 15-20 years and ours is 15 years old…
Apparently eventually the casting will crack, causing the contents of the heating system to tip itself all over the kitchen floor, then the header tank will graciously rinse away the sludge (and carry on doing so until you return to find an insurance claim scenario).
Now we don’t actually need to do anything yet, but the old boiler is supposedly about 65% efficient (although the rating plate implies 77-79% from the input and output ratings) whilst new boilers are up to 90% efficient, although they are more complex and cost a bit more.
Our new boiler will be made by Bosch and is of the condensing variety, now obligatory for all new and replacement boilers in the UK. Extra heat is extracted from the flue extract air by the condensation of the airborne water given off by the combustion process, requiring a water run-off pipe for the condensate. The boiler also needs an internal fan to blow the fumes over the heat exchanger (& out to the atmosphere) and also some extra wiring to the circulating pump to ensure that it runs on for a short while after the gas stops heating to prevent the innards overheating.
Regardless of all that, the installation is comparatively straight-forward in our case and the suppliers assure us it can be done in one day. It isn’t cheap, not too much change from £3k all in. Why did we choose to do it now? Well it does have a small payback in decreased gas bills (although it would take 20 years to cover the costs). It is better to replace it coming out of cold weather than having it fail in mid-winter and having to struggle on keeping warm with our solitary gas fire. (We do have an immersion heater in the water tank and an electric shower so we could at least keep clean without having to resort to kettles).
There is the other concern, of course. We can currently afford it from our savings. Next year, our savings might be worth a lot less if hyperinflation kicks in.
(Interesting take of this via Guido and the Bank of England Pension Fund).