Hi, can anyone help diagnose a fault with a Heatline Vizo? A few months back I noticed after running hot water that the DHW led would flash on the boiler, this resulted in us having to run the hot water tap slowly in order to get hot water until finally it became hard to get lukewarm water. At first I thought the heat exchanger may be blocked so this weekend I replaced the HE with a new one and for the first 20 minutes the boiler ran with no faults and we had hot water but this was short lived and now we have the same fault and having to reduce the flow from the tap to get hot water. I've uploaded a short video clip of the fault that I took using my phone.