It was the perfect storm.
The filter next to the heat plate had some muck not much but enough for there to be a problem. There was also a problem with the diverter valve and the pcb needed to be changed . Lastly the wire from the pcb also needed to be changed.
Regardless I have hot...
It was the electric wires going to diverter valve. They had been crimped and the voltage being sent was not enough for the valve to Open and close fully.
When the the valve was opened and closed manually by hand there was no heat being lost into the radiators when the hot water was turned...
Newbie here. I thought I would share this with everyone for thoughts plus for information - I will hopefully soon be able to post the solution.
We have a 7 year old Valliant EcoTec Plus 824 combi boiler.
Issues:
Had heat in certain radiators (Upstairs bar one) downstairs heating barely...