So I have a 3kW immersion and currently wired to a switcher fused spur. I'd like to add a boost timer and have seen Timeguard FBT4N.
https://www.timeguard.com/products/time/immersion-and-general-purpose-timeswitches/4-hour-electronic-boost-timer-and-fused-spur
Reads like the new timer fused...
