The engineer was very polite and courteous. However I was a little surprised when he said he was a plumber and not electrically qualified. I made it clear when calling that there was a fault with a Megaflo system which obviously has electrical heating elements. I had to call an electrician to explain to him what Economy 7 was as he was baffled why there was no power supply to the element. He understood afterwards that Economy 7 worked on cheap electric and only comes on between 1am and 7.30am. However, he was not able to test his diagnosis of a faulty thermostat. I was always led to believe that to be able to work on Mega Flo systems you had to be specifically certified to do so and would know about Economy 7 etc. Hopefully the thermostat will cure the fault and we can again have hot water..