I just had a shower pump installed.
The plumber didn't fit a Surrey flange but rather used a weld T joint from the hot water tank main supply pipe.
I know most pump manufacturers advise or require a flange. I assume this is for warranty purposes. Oddly, Aqualisa, on its power showers doesn't advise use of a flange.
Anyway, the T joint is a vertical drop from the main supply pipe at a point where the main supply point is perfectly horizontal.
My poor knowledge of physics tells me that there is little if any chance of air getting in to the pump supply because the water supply to the pump is a straight vertical drop from a straight horizontal supply pipe.
Is this correct?
I'm not confident enough to want to undertake a DIY flange installation and pip re-routing so I'm hoping the answer is that, possibly aside from strict warranty clauses, a flange isn't necessary in these circumstances.