Thanks for this .. ch came on as timed this morning abd am waiting for it to come on at 5pm on timer. Did not want to move it to constant as l was just grateful the house was warm this morning. HW is turned off just using the divrrt from heating for pots etc as we have electric showers thank goodness. I will see what the engineers say on Tuesday but l think they are a little baffled! Last call out they were here for 2 hrs plus. Really nice guys who have done everything they can!