Unfortunately the supply from the combi isnt that good, the mains cold
is
only 11 litres per minute at best.

Putting in a separate electric shower will achieve nothing at all. Poor
flow and pressure will always be there with a combi or an electric shower.

Firstly, I would get the mains pipe uprated from the street stopcock.
This
is necessary, so should be done. Secondly have the supply to the combi
from
the house stop cock uprated to 22mm if the new mains does not improve
matters substantially. It is a matter of working back from the mains
supply
and seeing how matters perform, then eliminating the next obvious
bottleneck.

Even if you have a poor flow and pressure in your district, I assume this
will not last forever, so uprating the mains will pay dividends when the
district is uprated.


A further question on the same topic.
We have fantastic pressure as far as I can tell. Only the kitchen tap is
directly connected to the mains at the minute and you can turn it full on
without soaking yourself. However I have asked Waterline what the pressure
is, to check everything out for a combi, and am waiting 3 weeks later for
some-one to get back to me...
This may be a stupid question , but is it possible we would need to get our
mains supply uprated for a combi supplying 2 showers, 1 bath and all the
other usual stuff? I wonder if we have good pressure but a small pipe and
performance can't be measured by the kitchen tap. How do I check what size
ours is? Sorry I know this is really really basic for you guys, but I know
so little, and am a bit of a give-it-a-go Jane.

Ta
Suzanne