So I have a pump assisted shower fed from immersion tank, when I turn on the valve there is a 5 min wait till the warm water comes through even though the mixing valve is turned to hot the pump sounds like it's working normally. Is it possible there could be some kind of airlock , it just makes no sense! The shower and the pump are only a couple of meters away from each other. It was not always like this it used to come through very quickly! Any ideas ?? Getting major grief from family members