balanced cold water

[rich d]

Hi
Looking to fit some pipework in bathroom before aquapoint heater is fitted in garage, so i can get on and tile.
I am having mixer taps on basin and bath (which also has shower head).
Will also be fitting an electric shower over bath.
The heater instructions say to supply mixer showers with take off from pressure reducing valve (balanced cold supply)
Should i be supplying my bath and basin taps from this also because they are mixers?
The instructions say not to supply cold taps, why? and does this mean i can't tee off this balanced cold to feed my toilet and electric shower.
I don't really want to run another cold water pipe from before the pressure reducing valve if i don't have to.
Hope that makes sense
Thanks

 

[Madrab]

All depends.... if they are single flow mixers then you need a balanced cold supply, if dual flow then it's not required.

The balanced cold feed is designed to feed outlets that need the supply delivered at the same pressure as the hot. The other outlets that only required a cold mains should be fed from a pre-prv supply pipe, saves putting too high a draw on the balanced feed and impacting on the flow to the balanced outlets.

 

[ScottishGasMan]

^^ what he said, but that does not mean you cant supply the toilet from the balanced supply. You just need to be aware that when flushing the toilet that the flow rate/available pressure may drop more to the balanced fittings while the toilet is refilling.

 

[rich d]

Thanks for your replies.
So i as i'm not sure if taps are single or dual flow (cheap ebay bathroom suite) i can just feed everything off balanced cold supply but will have to remember the temp of taps could fluctuate if toilet is refilling or elec shower on.
Bathroom is in garage with bedroom above so will be only used occasionally so am happy to live with this.
I also see from other posts that maybe i should fit check valves before each tap as the taps could be single flow and i should prevent any cross contamination/flow?

 

[ScottishGasMan]

Yea, check valves can stop the cold water being drawn through one mixer fitting into the hot and then to another hot. ie, I've seen many a faulty shower and some taps, where at another tap you draw hot water, and at the un used mixer the cold is passing into the hot and mixing down the temp which is then fed to the running hot tap giving cooler flow, the balancing valve alone should stop this as it will all be at the same pressure, but no harm in fitting check valves to ensure no problems.

 

[Madrab]

Whilst I agree with SGM that check valves can avoid hot being contaminated by cold and vice versa, their primary design is to stop hot water backflow into the mains cold water (where the cold mains pressure is lower than the hot) and contaminating it so check valves on the cold side only is usually recommended.

With a lot of thermostatic mixer showers there will already be one way valves built in but even if there is a pressure differential within the supply pipes (when the draw on the cold is excessive) then as the supplies are all post the PRV then both are balanced and you should have no issue, only slight dips in the supply when other cold outlets are used.

Personally I wouldn't use them as all they are, are a further restriction to the flow.