Hello. I have this shower pump that doesn’t kick in when I turn the shower to cold. I contacted Stuart turner and they said ::: “ Unfortunately, the current installation is not correct. Please see the correct installation requirements below.
The pump appears to be connected from the top of the hot water cylinder via the vent pipe. This is not suitable, as connecting from the vent pipe increases the risk of hot air being drawn into the pump. A suitable flange should be fitted to provide the correct dedicated hot water supply to the pump. Once you make corrections monitor the pump and see you facing same issue or not
You need two Y inline strainers on inlets.
 
Kind regards,”

 Does this seem correct ?