So i went into the Garage to take a look and guess what I saw.
Dooh, I guess the picture gives it away.
When a Gate Valve is fitted for the first time it will not hold high water pressure and will passed about 0.1% of water through.
As the Gate valve gets older then they only shut off 95 – 99%.
This is why the water pressure will go up easily.
The second problem I found here was the filling loop was attached, the question I ask is “how many plumber actually know the regulations fully?” The answer to this is, “not many”.
A filling loop when not in use, is supposed to be disconected at all times, so that there will be no water passing through or contamination to the cold water supply just incase there was a fault with the non return valve.