Thermostatic Shower cold -> luke warm

[Jimbo1982]

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

[Colin Wilson]

You can get pressure equalising valves, probably cost about =A340 :-}

I've had very good customer service from Plumbworld, so here's a prod=20 in their direction :-)

you can get "dial up pressure reducing valves" like=20 this:

a push, if you have an isolator in the vicinity, you might get away=20 with simply closing down the flow a little !

[Doctor Drivel]

"Colin Wilson" wrote in message news: [e-mail]...

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 :-)

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

needs the equalising valve.

[Colin Wilson]

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

[Doctor Drivel]

"Colin Wilson" wrote in message news: [e-mail]...

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.