@Yorkman – Yeah its an old model, it was installed in June. It worked ok for a month, then after that it was constantly switching on and off which meant sometimes it would be off when the cheap rate Octopus Energy was on. Initially it was there was too high a voltage coming into the house that was sorted by Northern Powegrid but I still had the same problem the Electrical contractors were finally given the go ahead by BP Pulse to replace the unit with a new one. Hope it all goes smoothly for you.