On 03/03/2021 11:22, bert wrote:
In article , Robin
writes
On 02/03/2021 23:57, Fredxx wrote:

snip
Â*If you know the kW of your boiler you would be able to calculate the
size of pipe you actually need. In domestic situations with limited
pipeÂ* runs 22mm copper pipe is a safe bet, plus to save embarrassment
to GasÂ* Safe installer Gas Safe have made a blanket requirement to
combis whereÂ* they must be piped in 22mm. Though I would be happy to
have the lastÂ* sectionin 15mm.


I don't want to give false hope to the OP who may well need a new gas
pipe.

But I've seen before on some sites that "Gas Safe regulations now
state that gas supply pipes from the meter to a combi boiler must be
at least 22mm". Smelt to me like a way to get more work and avoid the
bother of calculating pressure drops.Â* Gas Safe have no power to make
regulations.Â* And while the Gas Safety (Installation and Use)
Regulations were amended in 2018 I can't see anything in them about a
minimum pipe size. Have I missed something?


Only that when combi boilers first appeared a lot of installers used the
existing 15mm which was then found to be inadequate.

Yet another reason why combis are ****.

My peak hot water requirements are easily met with a mains pressure
cylinder allowing me to use a mere 12kw boiler.
You need around 50kW to get a decent hot water supply.




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