Under warranty ? Well I guess about 20 years ago in Germany it probably had one

The water heater was fitted last January before I took delivery of the motor by a firm in Norwich who was supposed to be proficient but in all honesty simply cocked the whole job up..
I do not believe it is scaled up but of course anything is possible.. I know the unit is quite an old one ( had to sort of take the burner to someone who matched it up, but apparently it is quite a common unit )
There does not seem to be a model number on it anywhere but I will take another look at it tomorrow..
Doubt the truth of the cylinder wrap..The wrap would have to be thermally coupled ( i.e. in solid and close coupling ) .. Thinking about it, I suppose you could actually do something with a thing like an electric blanket but it would be fairly inefficient to say the least !