Hi,

I have just installed a new thermostatic shower valve (Screwfix -
Moretti) and connected it with new 15 mm pipe work (around 5m to the
boiler) back to my 18 month old potterton combination boiler. Upon
testing the shower I found it runs from cold to luke warm even with
the temperature knob as high as it goes (there is no other temperature
control).

The hot pipe is very warm and I have left the shower running for a
couple of minutes with no difference, even when hot water arrives at
the taps in 10-15 seconds and as I said the pipes get very warm.

When fitting the therom control it suggested adding the supplied flow
restrictor (plastic) valves if the pressure was greater than 0.5 bar,
my system is so I fitted them.

When turning off the cold supply completly the shower runs very hot,
with the cold open a 1/4 of the way it is warmer but not as warm as I
think it should be. I also removed the flow restrictor from the hot
supply and think this made a little difference (i.e. it was a little
warmer).

The hot supply seems to have a lower pressure than the cold and I am
not sure if that is the problem and if there is anything that can be
done.

Basically I am out of ideas, I am not sure if it is an issue with
differing pressures, a faulty theromstatic valve or something else.

Any advice is greatly appreciated.

If you need and more info please let me know.

Cheers,

James

The hot supply seems to have a lower pressure than the cold and I am
not sure if that is the problem and if there is anything that can be
done.

You can get pressure equalising valves, probably cost about £40 :-}

I've had very good customer service from Plumbworld, so here's a prod
in their direction :-)

http://www.plumbworld.co.uk/pressure...-valve-344-230

Alternatively, you can get "dial up pressure reducing valves" like
this:

http://www.plumbworld.co.uk/dial-up-...ressure-0-4019

At a push, if you have an isolator in the vicinity, you might get away
with simply closing down the flow a little !

"Colin Wilson" o.uk wrote
in message g...
The hot supply seems to have a lower pressure than the cold and I am
not sure if that is the problem and if there is anything that can be
done.

You can get pressure equalising valves, probably cost about £40 :-}

I've had very good customer service from Plumbworld, so here's a prod
in their direction :-)

http://www.plumbworld.co.uk/pressure...-valve-344-230

Alternatively, you can get "dial up pressure reducing valves" like
this:

http://www.plumbworld.co.uk/dial-up-...ressure-0-4019
___________

He needs the equalising valve.

I've had very good customer service from Plumbworld, so here's a prod
in their direction :-)
Alternatively, you can get "dial up pressure reducing valves" like
this:
He needs the equalising valve.

Daft question perhaps, but why would the pressure reducing valve not
work ? - ISTM that it's only the massively unequal pressure of the
cold that's overpowering / restricting the flow of the hot out of the
shower.

FWIW ours does the same if I open the valve too much on the shower*
(although you still get very good flow rates)

* a thermostatic Hansgrohe

"Colin Wilson" o.uk wrote
in message g...
I've had very good customer service from Plumbworld, so here's a prod
in their direction :-)
Alternatively, you can get "dial up pressure reducing valves" like
this:
He needs the equalising valve.

Daft question perhaps, but why would the pressure reducing valve not
work ? - ISTM that it's only the massively unequal pressure of the
cold that's overpowering / restricting the flow of the hot out of the
shower.

FWIW ours does the same if I open the valve too much on the shower*
(although you still get very good flow rates)

* a thermostatic Hansgrohe

An equalising valve drops the highest pressure to the lowest and makes the
hot and cold equal. If a tap is turned on, or a toilet flushed, there is
slight glitch and then the pressures equal out and scalding or cold shocks.