I am planning to re-furbish an en-suite bathroom, and am considering
installing a Stuart-Turner Monsoon twin impellor pump. I currently have
a Mira Vigour wall-mounted power shower with built-in pump but would
like to replace it with something with a bit more €śurge€ť.
The instructions for the Monsoon say €śThe pump must, for optimum
performance, be sited as close as possible to and never more than 4
metres from the HOT WATER cylinder€ť.
In my case this would be very difficult to achieve because the hot and
cold feeds to the en-suite take different paths and only meet when they
get there (see drawing at
https://app.box.com/s/20x0sg5z9rpwsh27mi2wwsth3d7fk5g0). The hot runs
under the landing and bedroom floors, and the cold runs through the
roof-space. If I install the pump in my preferred location inside a
vanity unit in the en-suite, the pipe run from the hot cylinder to the
pump would be about 10 metres. I have spoken to a droid on the S-T
support helpline, who simply reiterated what it says in the instructions
but wasnt able to explain the rationale behind this. I am struggling to
understand which law of Physics would be violated if the distance
between hot cylinder and pump is more than 4 metres. How does the pump
know how far it is from the cylinder? If it's a cavitation issue, isn't
head and pipe size more important than horizontal distance? What are the
likely consequences of installing it in my preferred location? I accept
that I may need an Essex flange (or similar) in the cylinder to avoid
sucking the vent pipe dry.
Am I missing something?
--
Cheers,
Roger