Within this Main Thermostats category we list main boiler control thermostats which are normally a secondary boiler protection device as most systems
are now controlled by external thermostats, but it adds simple protection of the Main appliance by managing the internal temperature of the boiler or
appliance. Also Main Overheat thermostats which switch the boiler off in the unlikely event of the boiler overheating. Hi and low limit thermostats which
basically govern the higher and lower temperatures required for the Main appliance. More modern Main boilers use Thermistors or NTC Probes
for electronically controlling the temperatures of both the heating and domestic hot water and Main condensing boilers also use thermistors for
monitoring flue gas temperatures.