The cold water supply to my electric shower comes from the rising main
in the bathroom ,

The vertical mains pipe is in 22mm then goes under the floor to the
bath in 22mm as well then a vertical 22mm feed goes to the shower via
a full bore valve like this .

http://www.screwfix.com/app/sfd/cat/...17293&ts=99213

Then the final 12" or so is in 15mm to the shower inlet .

If the part after the valve was all in 15mm ( apart from a short piece
to reduce it to 15mm) would that make any difference to either the
pressure or flow rate .?

There has been an issue with the shower cycling but it happened at the
weekend but I havent pinned down the reason . I can understand
intermittent problems with neighbours ( it's an 8 flatted property) if
they are running cold water for baths,dishes,toilets at the same time
as the shower is being used ( everyone has combi boilers if that is
relevant) but on Saturday I put my ear to the p/board behind which is
the rising main and I could hear it running and it seemed to go on for
ages which confused me a bit.

Stuart

In article , Stuart B
writes
The cold water supply to my electric shower comes from the rising main
in the bathroom ,

The vertical mains pipe is in 22mm then goes under the floor to the
bath in 22mm as well then a vertical 22mm feed goes to the shower via
a full bore valve like this .

http://www.screwfix.com/app/sfd/cat/...17293&ts=99213

Then the final 12" or so is in 15mm to the shower inlet .

If the part after the valve was all in 15mm ( apart from a short piece
to reduce it to 15mm) would that make any difference to either the
pressure or flow rate .?

Nope, electric showers are all low flow, high drop and that small length of
15mm is unlikely to make a difference.

There has been an issue with the shower cycling but it happened at the
weekend but I havent pinned down the reason . I can understand
intermittent problems with neighbours ( it's an 8 flatted property) if
they are running cold water for baths,dishes,toilets at the same time
as the shower is being used ( everyone has combi boilers if that is
relevant) but on Saturday I put my ear to the p/board behind which is
the rising main and I could hear it running and it seemed to go on for
ages which confused me a bit.

I think you've hit the nail there, tenements (I'm assuming you're in one)
were never meant to draw their water direct from the mains, each side of
the close had its own 200 gallon tank to feed just 4 flats so no-one ran low
on supply and all but the top flat had a healthy head of between 15 & 60
feet. The close likely has a single 22mm copper feed (or equivalent) so
there's no hope of simultaneous mains fed showers first thing in the
morning.

I'm in a tenement on the ground floor and have retained the loft tank feed
for my (stored) hot water feed. With a 60' head there is no problem with
pressure on my stored water shower but I do have a mains fed electric
backup and I notice fluctuations on that at peak times.

Depending on your position in the block, could you reconsider using tank
feed for the shower? Alternatively, you may get a result by using an
adjustable pressure regulator to actually reduce the pressure to the
shower. You'd then open up the shower valve to cope with the lower
pressure and you wouldn't notice loss in pressure until it dropped below
the regulated level (+ a bit).

If you're on the ground floor, tap a direct 22mm feed off the main pipe right
as it enters the property, then you get first dibs on the pressure ;-)

Was it you that was having low pressure problems after Scottish Water
was doing some work? If so, keep at them and go to the regulator. I'm sure
the pressure/flow dropped here after the replaced the mains with plastic
but it is bearable.
--
fred
Plusnet - I hope you like vanilla

On Tue, 20 Mar 2007 19:38:26 GMT, fred wrote:

In article , Stuart B
writes
The cold water supply to my electric shower comes from the rising main
in the bathroom ,

The vertical mains pipe is in 22mm then goes under the floor to the
bath in 22mm as well then a vertical 22mm feed goes to the shower via
a full bore valve like this .

http://www.screwfix.com/app/sfd/cat/...17293&ts=99213

Then the final 12" or so is in 15mm to the shower inlet .

If the part after the valve was all in 15mm ( apart from a short piece
to reduce it to 15mm) would that make any difference to either the
pressure or flow rate .?

Nope, electric showers are all low flow, high drop and that small length of
15mm is unlikely to make a difference.

There has been an issue with the shower cycling but it happened at the
weekend but I havent pinned down the reason . I can understand
intermittent problems with neighbours ( it's an 8 flatted property) if
they are running cold water for baths,dishes,toilets at the same time
as the shower is being used ( everyone has combi boilers if that is
relevant) but on Saturday I put my ear to the p/board behind which is
the rising main and I could hear it running and it seemed to go on for
ages which confused me a bit.

I think you've hit the nail there, tenements (I'm assuming you're in one)
were never meant to draw their water direct from the mains, each side of
the close had its own 200 gallon tank to feed just 4 flats so no-one ran low
on supply and all but the top flat had a healthy head of between 15 & 60
feet. The close likely has a single 22mm copper feed (or equivalent) so
there's no hope of simultaneous mains fed showers first thing in the
morning.

I'm in a tenement on the ground floor and have retained the loft tank feed
for my (stored) hot water feed. With a 60' head there is no problem with
pressure on my stored water shower but I do have a mains fed electric
backup and I notice fluctuations on that at peak times.

Depending on your position in the block, could you reconsider using tank
feed for the shower? Alternatively, you may get a result by using an
adjustable pressure regulator to actually reduce the pressure to the
shower. You'd then open up the shower valve to cope with the lower
pressure and you wouldn't notice loss in pressure until it dropped below
the regulated level (+ a bit).

If you're on the ground floor, tap a direct 22mm feed off the main pipe right
as it enters the property, then you get first dibs on the pressure ;-)

Was it you that was having low pressure problems after Scottish Water
was doing some work? If so, keep at them and go to the regulator. I'm sure
the pressure/flow dropped here after the replaced the mains with plastic
but it is bearable.

I'm on the 2nd floor . There are cold tanks in the loft...one per side
...but they were only used for HW cylinders and I was the last on my
side to get a combi recently so i suggested to the Factor that they
cap the supply to the tank on my side and drain it down as it wouldn't
be getting used . The feed from it is/was in the kitchen anyway so
using it isn't an option even if I wanted to use it .

You are right in thinking that I posted a message about a drop in
pressure after SW did some work recently . The guy did come out but at
the time everything seemed fine .
After I posted this topic I bought a water pressure gauge ( it was
only £10) and I fitted it this afternoon and the pressure was 3 Bar .
It went down to just over 2 Barearly evening but now ( just before
midnight) it has gone to just over 3 Bar . Even when I turn on the
cold in the Basin it still stays above 2 Bar .... I'll se what it is
in the morning although it's usually later in the morning before I use
the shower .

What I want is to see what it is at the w/end . I don't know how far
the effect on me of others using the cold water spreads . Will it just
be this close or also the next one or the one after that as well. ????

In article , Stuart B
writes

I'm on the 2nd floor . There are cold tanks in the loft...one per side
..but they were only used for HW cylinders and I was the last on my
side to get a combi recently so i suggested to the Factor that they
cap the supply to the tank on my side and drain it down as it wouldn't
be getting used . The feed from it is/was in the kitchen anyway so
using it isn't an option even if I wanted to use it .

You are right in thinking that I posted a message about a drop in
pressure after SW did some work recently . The guy did come out but at
the time everything seemed fine .
After I posted this topic I bought a water pressure gauge ( it was
only £10) and I fitted it this afternoon and the pressure was 3 Bar .
It went down to just over 2 Barearly evening but now ( just before
midnight) it has gone to just over 3 Bar . Even when I turn on the
cold in the Basin it still stays above 2 Bar .... I'll se what it is
in the morning although it's usually later in the morning before I use
the shower .

2 bar with the basin open does sounds healthy, is that fully open? How
about the bath? I think you'd only get a bar or so from the loft tank to the
2nd floor.

Just looked at the specs for a (random) triton electric shower and it was
1bar min for 9.5kw and 1.5bar for 10.5kw. It looked quite an expensive
model (T100xr) and it mentioned flow stabilisation:

"The stabiliser valve minimises variations in shower temperature during
mains water pressure changes. If changes in shower temperature are
experienced during normal use, it will most likely be caused by the water
pressure falling near to or below the minimum level. The drop in pressure
may be due to water being drawn off at other points in the house whilst the
shower is in use. If pressure drops appreciably below the minimum, the
heating elements will automatically cut out. "

Don't know if yours might have that, expensive one more likely I imagine,
cheapie less likely.

If it doesn't have one then I can see variations between 3&2bar upsetting
the flow & therefore temp quite a bit.

As a workaround I found some stand alone pressure reducers at BES:
http://www.bes.ltd.uk/products/109.asp , if your shower doesn't have a
stabiliser then this might help but I don't know what their minimum drop is,
which would be critical. Note I haven't used these, 20quid to try.

What I want is to see what it is at the w/end . I don't know how far
the effect on me of others using the cold water spreads . Will it just
be this close or also the next one or the one after that as well. ????
Think the gauge is a good idea.
--
fred
Plusnet - I hope you like vanilla