I recently had to change the multiport valve assembly that sits on top of the sand filter, I also had to change the water direction valves, the produced a lot of air in the system that meant bleeding the pump to get rid of the air.
My sand filter is a Micron S750 High Rate.
I have 4 number direction valves that carry out the following: -
Valve No.1 returns water to the pool from the filter
Valves 2,3 & 4 direct water from the pool through the sand filter
To clean the bottom of the pool with a suction hose, Valves 1 & 4 are opened, 2 &3 remain closed
To filter the water in the pool Valves 2 & 4 are opened, 1 & 3 remain closed
To backwash the sand filter Valve 3 only is opened,the others remain closed
To send water from the holding tank/reservoir to top up the pool water level, Valves 3 & 4 are opened,1 & 2 remain closed
All these configurations work well except for topping up the pool, no water is being passed from the holding tank/reservoir into the pool.
There is still some air in the system but that should not affect the flow of water back to the pool.
Does anyone have any suggestions as to why this problem is occurring and any remedies that I can try.