I have an Ideal Mexico RS80 which is not igniting. The property has been empty for years so I suspect the gas valve has seized. My question is should I have the boiler repaired or have a new condensing boiler installed? My thinking is the old cast iron boilers will run until spares run out (and will pump sludge until the cows come home) whereas a new boiler is way more efficient but (a) any sludge will destroy the heat exchanger (b) there is far more to go wrong and (c) the new boiler will need replacing after 10 or so years anyway. So the efficiency cost saving is offset by the 10 year replacement cost. Furthermore, if i keep the old boiler can i have someone move it? Or does that trigger replacement? Thanks