Pipe restrictions and flow rates

[TheOldFellow]

I'm fitting a new bath. It has a Geberit bath filler, which fills through the 'andle for the waste. As my system is mains hot and cold, I am fitting check valves in both hot and cold supplies - Water Regs, I think. The pipe is 22mm.

Now the check valves that I have are quite restricted in diameter inside, looks about 12mm. Is this right? Seems to me that this will restrict the flow something rotten. How can I calculate flow rates for pipes of different bores, and what corrections are needed for short restrictions like this?

R.

[Dave Liquorice]

Doesn't the rising main already have a check valve? AFAIK the regs only worry about back siphonage into the mains.

[Invisible Man]

Can you not fit full flow check valves?

[TheOldFellow]

Can you suggest where I can find them?

[TheOldFellow]

Yes, but I am worried about cross feed between the hot and cold, and siphoning from the bath.

R.

[Tim Downie]

Um, but if both your H&C are mains pressure how is that going to happen? I'd check the regs. I suspect you don't need one.

Tim

[polly filler]

You won't need them, if it's this one you're using, Gerber113 Geberit bath filler it needs to be tank fed

[Dave Liquorice]

I think I need an expansion on "Geberit bath filler, which fills through the 'andle for the waste." Link?

Most "mixer" taps actually keep the H & C seperate right to the end of the spout but with a name like "Geberit" this may be an European device and they do things "differently"...

[TheOldFellow]

Nothing in the installation instructions about that, and it was sold to me as suitable for a fully mains fed system. Can you elucidate, or point to a definitive source? You have me worried that I've been sold something unsuitable.

R.

[polly filler]

ukbathrooms.com sell them, to comply with regs need to be tank fed

[TheOldFellow]

I'll check with my supplier. But thanks for the 'heads up' on this, if it turns out to need a tank, they can have it back.

R.

[TheOldFellow]

Checked with Geberit UK, and they say there is no problem.

R.

[polly filler]

Thats not what it says on their blurb, good look with it anyway

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