Mixer shower- cold off mains?

[meggles]

while i was out of the country, the plumber installed our thermostatic mixer shower off cold tank in loft & hot water tank in airing cupboard. pressure is OK.

i knew that a pump would most likely be needed and so i've asked previously on this forum for recomendation- still deciding between 1.5 and 2.3 bar... thanks for your insights.

the plumber mentioned to my boyfriend- that he could boost the pressure by putting the cold off the mains water. would this work? what would be the advantage? is this legal? i know i can hook the mains up to a pump. any insight would be most helpful.

 

[JohnD]

in most cases, supplying high-pressure cold from the main, and low-pressure hot from the tank, will make it difficult to regulate the temperature. Obviously pressure at Hot will not be increased. it also introduces the risk that the cold water will leak through and travel up the hot pipes.

There are a few showers with a mechanism that uses the cold pressure to pump the hot. Have you got one of these special showers? the Trevi Boost is one. It costs several hundred pounds.

If not, you would do better with tank hot and cold, and a pump.

 

[meggles]

no- i have a standard triton thermostatic bar mixer shower.

i hear what you're saying. i think i'll stick with the twin impeller pump idea.

 

[Breesey]

Meggles, don't pump the mains though!

You will need dedicated hot and cold supplies from the cistern and hwc to the pump.

 

[meggles]

thanks for clarifying...

no the pump will be attached to the cold tank & hot tanks. when the plumber put the mixer shower in- i told them that they woudl most likely be putting a pump in shortly (didn't have time to sort that out b/f installing). i was also curious what the pressure woudl be like. it isn't too too bad... just not great.