As far as I know it functions just the same as on the high heater setting – higher gas/heat output (2 clicks)
We usually run the heating on the lower setting (lower gas/heat output) as the fan is quieter.
If its cold use the high setting to get up to temperature then use the lower setting to maintain the temperature. From practical experience I would say that I think the temperature drops away a little before the thermostat kicks in again…..but that is probably because being an older design it uses bi-metallic strips or something (now outlawed by EU regs) rather than more modern technology.
Fred
