Looking to replace old storage heater and need to know the output rating?

When replacing an old heater need to have room heating calculation carried out to correctly advise the heater size.

Heat calculator can be found here: https://www.dimplex.co.uk/en-gb/room-heating-calculator

This would apply when replacing an XL XLS CXL, DuoHeat etc with a Quantum RF or XLE storage heater.