Hi Eoin

No, Only the hot water goes through the reducing valve. The cold water
runs at mains pressure (and the shower mixer is designed to accomodate
that). The plumber claimed that setting it up this way allowed the
cold water to "pull" the hot water through the system and actually
increased the haot water flow rate.  I guess it would happen if there
was a low pressure area in the mixer - similar to a siphon effect.

The filter screen on the shower mixer (hot water) has been removed as
it was introducing an additional pressure drop. That was done about 3
years ago and so far I've only had to clean out the mixer once.

RP




On 25/03/2008, Eoin Ross <eross@chemstation.com> wrote:
> Is the HOT/COLD pressure the same @ the shower (While flowing)?
>
> Sounds like you have a flow restriction on the hot water side of the shower - possible swarf/grit has found its way to a screen on the hot side shower valve?  It may help to think of Pressure as Voltage, and Flow as current. Narrowed lines/blockages act like resistors.
>


> >>> rhprosser@gmail.com 24 Mar 08 02:58:04 >>>
> On 24/03/2008, Bob Blick <bobblick@ftml.net> wrote:
> >
> ><SNIP>
> I'm having a similar problem at the moment with a pressure reducing
> valve. If I adjust it for reasonable pressure in the upstairs shower,
> it eventually develops a slow leak and I start losing hot water
> through the overflow. If I back off the pressure to stop the overflow,
> then we get cold showers. A new washer generally fixes the problem for
> about 6 months but that''s it. Not sign of grit or damage to the
> sealing face where the washer sits.  I've tried sanding the surface of
> the washer which removes the hard oxydised surface and it appears to
> help but it doesn't last
>
> We first noticed the problem when the council fitted a water meter and
> there was grit/swarf in the system but that was a long time ago and it
> now appears clean.
>
> One solution appears to be to increase the height of the overflow so
> more back pressure will develop before it starts to drip. This will
> apply more pressure to the valve & hopefully turn it off harder. But
> I'm already close to the maximum pressure of the hot water cylendar.
>
> The good side of things is that it's an easy job to replace the washer.
>
> Any ideas?
>
> Richard P
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> Eoin Ross
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