Mains Cold & Pumped Hot to Thermostatic Mixer Shower?

[Boxerman]

I have very good cold water pressure, can I therefore run it straight to a thermostatic mixer shower with a pumped hot feed, if so will it need balancing? If not, can anyone recommend a very quiet/silent pump that can be used on both hot and cold although it's going to be a right pain to get the cold to the shower if I can't use direct from the mains.

Thanks

 

[ajs heating]

if you what to use mains cold gravity hot fit a trevi boost shower otherwise you need to run the cold from tank.
i always use salamander pumps or stuart turner pumps not this plastic rubbish you buy down the local diy.

trevi boost uses mains cold to pull the hot through at mains pressure.

 

[Boxerman]

Looked at the Trevi Boost but the wife wanted a antique large head type shower, so it looks like trailing tank fed cold through the house then.....bugger !!

 

[Timmyturtle]

Please correct me if im wrong but could you not run a single pump for the hot and put a pressure reducer(set at the pump output pressure) for the mains cold??

Just an idea....

 

[ajs heating]

do agree with you .
i've never done it and probably never would. i always run another cold feed least i know when it's done it's going to work.
and when i've spoke to pump companys they never favour having one on pump and one from the mains even though it's reduced.

but by almeans try it you'll soon find out.

 

[Timmyturtle]

thats what I thought...in theory it should be fine......waits to be told otherwise

 

[chrishutt]

In principle you could have cold at mains pressure and hot from a tank and boosted by a pump. The important thing is that the dynamic pressures should be reasonably balanced, at least to a degree acceptable to the pump manufacturer. This is easily achieved, if necessary using a Pressure Reducing Valve on the cold side.

Static pressures would obviously be imbalanced and you would rely on the non return valve (NRV) in the hot supply side to the shower to prevent higher pressure mains flowing through the valve and pushing the hot water back up into the feed tank. Sadly NRVs aren't that reliable these days and the pump manufacturers might object to additional NRVs being fitted on the hot side.

 

[Timmyturtle]

I spoke to a colleage today who has seen a pressure reducer on the mains cold,and pumped hot and it was working fine

Needs nrv on the mains too