Ariston Thermostat 691216

Where hot water is stored in a cylinder and heated by a separate boiler, a dual control thermostat is required to avoid the cylinder being overheated. The Dual Cylinder thermostat combines both the controller and limit thermostats into one common unit, they are designed to be surface mounted they generally have two spdt probes located at the back, and these go into the thermostat pocket located on the cylinder. The thermostats are designed to restrict the water temperature to around 65°C to provide safety and prevent scalding water running through the pipework. The dual thermostats also have an integrated reset button in the case of them tripping out. Some of the older style unvented cylinders would have a single control thermostat and a separate cut out thermostat these were made before the regulation change in 2010 which states cylinders must have a dual thermostat fitted.