Replace outside tap

15 Oct 2023
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United Kingdom

I want to replace my outside tap and pipework as the old one doesn't have a Double check valve (inside or out).

I have purchased A DCV and isolator, but do I need a drain-cock on the inside?

also is it - isolation valve then DCV?
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Yes if you want to follow the water regulations
Thank you, the reason I'm altering the pipe is to meet the regs.

It's no bother fitting one, but all the piping goes upwards vertically so where should it go, just above the DCV?

Does the DCV go after the isolator valve?
Last edited:
The drain off would be the last fitting before the tap, so it can be drained down to prevent freezing. Yes, as per my previous reply, the dcv goes after the isolation valve.
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Thank you for your reply (y)

The pipe feeds the filling loop to the boiler and then the outside tap, would there be an issue if I put the DCV before the tap, filling loop and isolator?

Two DCVs would then protect the boiler, but it would give me more room to work!

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