Shower supply problem

[longdogs]

I have been asked to fit a mixer shower in a downstairs bathroom, using a typical twin impeller pump. The cold water cistern is in an upstairs bedroom and offset from the downstairs hot water cylinder by about six feet resulting in pipes dissapearing into the centre of the house. This makes it impossible to run a dedicated cold feed to the pump from the water cistern, without demolishing half the house.

I contacted the pump manufacturer explaining the problem and their technical bods suggested swapping the twin impeller pump for a single impeller pump ( to pump the hot ) and to supply the cold directly from the mains ( which is in said airing cupboard ) via a pressure reducing valve, set at the same pressure as the hot pump.

The twin impeller pump was returned and swapped for a single impeller. I then rang the technical bods for the new pump who told me that I was not allowed to do this.

Can anyone see any problems with this set up? What about a non- return valve on each supply?

Any comments would be appreciated

Many thanks

 

[ChrisR]

Can't see you're breaking any regs seriously if you use a double check valve in each supply to the mixer. Use 22mm ones for lower resistance than 15's.

 

[cozzmic]

Why not fit a venturi type shower, back fed HW and cold mains gives good flow rate as it uses the mains pressure. No pump required no regs to break. Trevi make one very good, little pricey.

 

[longdogs]

Thanks for the replies guys

Fortunately the problem has been resolved by going back to the twin impeller idea and running the cold feed via a different route, which is not aesthetically ideal but was the suggestion of the householder. Everything is now working fine.

Thanks

 

[Paul Barker]

They'd have been better off with a trevi boost and would have saved money. Never mind.

 

[longdogs]

They'd have been better off with a trevi boost and would have saved money. Never mind.

thanks. Will look into this for the next time the problem comes up.