honeywell l641a1005 attached to hot water cylinder with spring band, i have tried turning switch down but has no effect any answers appreciated?

waterman, October 2012

Make sure the immersion heater isn't swithced on (by accident)

oops, October 2012

Could be the unit faulty, or control cct fault or XX or XX. Start with temp unit, does it click when you adjust temperature. Probably not if water that hot, turn system off, to let it cool down, or take sensor of of tank, then check if clicks. clicking would indicate ok, and fault is in control. More details.

SD, October 2012