"Owain" wrote in message
...
JustMe wrote:
Currently I have an electric shower which takes a cold feed and heats as
the
water passes through. It's a bit on the slow and drizzly side, so I want
to
know what my options are for POWER.
I have a combi boiler which drives most of my hot water needs and
there's no
header tank currently installed anywhere.
AIUI I can run a mixer tap+shower direct from hot and cold water
supplies
which, given the pressure from the tap at the moment, should be an
improvement on the electric.

Yes. If you have a 10kW shower and a 30kW combi then you should get
about three times the *flow*. (The pressure will still be the same.)

But if I want real power, then a pump is
required. This is where I get confused:
From what I've read, a pump cannot have hot water fed directly from a
combi
boiler. It seems I have two options:

Correct, for a pump to work you need a source of *stored* and
*unpressurised* hot water.

1) Header tank above the bathroom, fed in to pump and on to shower -
seems
to be the superior solution, but I don't quite understand how this
works. Is
there an immersion in the header tank or does the tank fill up with hot
water from the combi which then provides a reservoir for the pump and
shower?

No and no.

In which case, where does a mix of cold water come in for
temperature control? Or does the header tank store cold water which is
heated somewhere further down the line?

Yes, you would need a hot water cylinder (which can be heated off the
radiator circuit of the combi, if you want it to be).

2) Combined electric shower/pump - cold water feed, wall mount unit
combines
heater and pump - simpler but not as powerful/hard/fast?

No improvement, as the limiting factor is the 10kW available to any
electrically heated shower.

Owain

Thanks for your advice. I have a few follow up questions/clarifications...

To get the best performance from my new shower, you suggest I buy pump+hot
water cylinder alongside my new shower head and mixer taps?

The hot water cylinder can be heated off the radiator circuit. Does that
mean use the same hot water as flows through the central heating - so I'd be
showering in the water that might've passed through all the radiators? Or
does that work differently?

I've had a Google, and these look a lot like the big immersion heaters I've
seen - presumably these can also be heated with dedicated electric
immersion, too? These seem somewhat bulky just for my personal shower use
(single occupancy household) - or am I misunderstanding?

The path would presumably be: Cold water supply - Hot Water Cylinder -
Pump - Shower head.

I assume that the cylinder itself can be located anywhere near to the
shower - can that be above/below/same level, or does it need to be somewhere
specific?

I'm not going to be doing the advanced stuff myself, but will be helping - I
just need to state what I want, up front.

Cheers.