Check valves for a mixer tap with shower hose?

[proftanda]

Hi,

I'm fitting a mixer tap with a shower hose to the bath in my flat.

The cold is from a mains supply and the hot from a gravity fed supply with through an instant water heater. The cold is about 4bar and the hot 1bar (or less). This will be the only mixer tap so far in my flat (though I'm also planning to fit mixers on the bathroom sink and in the kitchen) and I can't see any non-return valves between the existing fitting and where the cold supply enters my flat.

I've read that you're supposed to install a non-return valves on fittings that mix hot and cold in the body of the fitting (which, I'm guessing the shower hose does), however, I've also read that non-return valves will reduce the pressure/flow. This might be an issue for me having an already low pressure on the hot.

Do I need to fit a non-return valve on the hot and can anyone suggest a good one for low pressure if I do? For example, would something like this swing check valve meet water regs for hot?
http://www.bes.co.uk/products/098.asp#7463

For the cold, can I fit a single non-return valve for both the bath and the bathroom sink or do I need to fit separate valves downstream of where the pipe splits to feed the bath and the bathroom sink?

Finally, would it be worth fitting a pressure reducing valve for the cold with this kind of pressure difference? Again, could I fit it upstream to control the pressure for both the bath and the bathroom sink?

Thanks in advance for any tips with this!

Cheers,
Nick

 

[Madrab]

Yes, check valve on the cold to protect the mains, not needed on the hot.

You will need to balance the supply to the mixer if there's 3 bar difference. A Pressure Reducing Valve (PRV) on the cold to the mixer. That can go in before the split to the outlets of the bath and sink, if you need to control both.

You want a check valve in-line as close to the cold outlet as possible.

 

[proftanda]

Thanks Rob. Just what I needed!