Update:turned on the control box this morning and again made a loud bang and lit up inside like something had blown. What else could be causing the box to blow as happened to last box that was installed and working for over a year and a half.
Ho I've just had my hortsmann economy 7 timer box replaced and it has been heating the water constantly even when I have turned the dial round so it is not set to come on. This has made no difference and the water continues to heat up unless turn it off by the hortsmann box.The plumber I had...