Owain wrote:
David Hearn wrote:

I'm in the process of fitting a new sink + mono mixer tap (ie. single
hole mixer). As we have unbalanced supplies, it sounds like we need
them - but what is the purpose? To stop mains pressure water ending
up in our hot water pipes, or to stop contamination going back up the
cold water pipe from the hot water?


Officially the latter, but in practice the former as well. If it's a
single outlet mixer you will probably find that it won't "mix" very well
on the different pressure supplies.

Separate outlet mixer strongly preferred for kitchen sinks and other
potable water applications. The concentric outlet type with the cold
wired to the outer also helps keep the spout cool to touch.

Owain

The diagram of the tap included in the 'instructions' shows 2 separate
channels with it being open at the spout before going into the 'flow
straightener' (weird name!)

So, do you think that I'll actually need a check valve with this
arrangement?

Thanks

D