Roger Mills wrote:
On 10/04/2021 08:42, Tim+ wrote:
Roger Mills wrote:
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?
I fannied around for years with pumps, and then upgraded to an unvented
cylinder. Wish Id done that to start with.
Unless you have poor mains pressure in which case your options are limited,
Id suggest an unvented cylinder (or a thermal store).
In my holiday flat I've got an unvented cylinder allowing mains pressure
hot and cold to be supplied to a bar mixer - but it doesn't have
anything like as much urge as I would like. It's worse than my current
rather feeble "power shower" at my main home.
Clearly you have mains pressure/flow restriction in that flat then. Does
this apply to your main residence though?
If you still want to go with a pump could you not put your pump by the HW
tank and run the cold feed to the shower back up to the loft and tie it in
there?
Possibly, but it's a bit messy bringing the cold down and then up again.
No-one has yet explained why my preferred solution wouldn't work.
Im sure it would work, after a fashion. Im sure cavitation issues are why
ST recommend fitting close to the hot tank. I doubt youll get a
definitive answer. You may just have to try it and report back. ;-)
Tim
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