The ES-CTDE/B will call for heat when first connected to lift the Cylinder to 61°C and hold it there for one hour to eliminate any legionella bacteria that may be lying in the Cylinder. This is its first “anti-legionella” boost – thereafter, this process is repeated every week. After this initial hour the thermostat will be controlled by the Programmer and will hold the cylinder at whatever (lower) temperature the adjustable in-built thermostat is set at. Most Cylinders can be set around 48°C which is much more economical than holding at around 65°C and always having to add cold water whenever the hot is used.
However, if your Boiler output temperature is too low, then the ESCTDE/B cannot get to 61°C so it just keeps trying. The solution is simply to turn up your Boiler Output temperature and this will enable the Cylinder to reach 61°C, after an hour at this temperature the unit will obey the Programmer and operate to the set point (for example 48°C.)
