"Set Square" wrote in message ...
In an earlier contribution to this discussion,
andyd wrote:



andyd

Even at the maximum setting, it is still a thermostat and will switch off
when the set - albeit high - temperature is reached. It *doesn't* become a
permanently on switch, as implied by the question!



sorry i wasnt trying to imply that the thermostat would become a
permanently on switch, however with my he35 controlled by a sunvic
programmable room thermostat set at 20C and the boiler thermostat set
at maximum the boiler operates until the room thermostat switches it
off, when the boiler thermostat is set at the midway position the
boiler switches on and off until the room thermostat is satisfied, the
question was only regarding the most economical way to run the boiler

thanks
andyd