On 14/04/2018 01:12, Roger Hayter wrote:
wrote:

On Friday, 13 April 2018 21:44:06 UTC+1, Jonno wrote: I want to install
a direct un-vented hot water cylinder in a flat. The install
instructions call for 22mm diameter water supply line, the main riser
supply to the building is 22m and then reduces to 15mm before the stop
valve. Do i need to isolate the main riser into the building in order to
replace the 15mm stop valve with 22mm or can I step up the pipe
diameter back to 22m after the 15mm stop valve without affecting the
performance of the cylinder.

15mm is likely to give unsatisfactory flow.

If the unvented cylinder is over 15 litres you must have an Unvented Hot
Water certificate to do this work.

Owain

I rather like the idea of an unvented certificate. Is that really it's
name?


Yes, it comes in a sealed container. g
--
Cheers,
Roger
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