We had a worcester bosch 240 boiler fitted about 11 years ago on a mixed 2 pipe and one pipe system, at present it is working fine, but when we had it fitted we were told we had to leave a radiator turned on fully all the while, which wasn't a problem in the past, but now the gas is so expensive we need to know if this is true, and if so why?

Bob, August 2008

possibly, the radiator in question is to act as a bye-pass radiator, i.e to dissipate the remnant heat when the boiler ends its on-off cycle, so therefore keep the valves of the radiator OPEN (on) at both ends

baz, August 2008