size of tails for a wall mounted bath filler

[elmsoft]

I am fitting a shower bath for a friend who chose a wall mounted bath filler. The unit the showroom supplied came with 15mm flexi tails. I suggested that 22mm is the right diameter for bath supply but in fact finding a unit with 22mm inputs has proved difficult. Starting to wonder if 15mm supply to baths is the new standard. But surely the speed of filling is going to be restricted. Why run 22mm tubing to the bath and then reduce to 15mm inputs.

I am confused. Can anyone enlighten me?

Thanks

 

[Charnwood]

If the hot tap is fed from a combi boiler it will take roughly a fortnight to fill even if you use 42mm copper from the boiler.

Combis were heralded as the dogs *******s (OK Mr automatic language censor, try this: ********) when they first came out.
Many are finding they are a load of *******s (********) in practice.

 

[doitall]

What Charnwood is trying to say is, the type of fitting you have is designed for mains pressure, so 15mm should be ok.

He also correctly stated if the custard has a combi, someone is going to be disappointed with the end result.

 

[elmsoft]

Thanks for the replies.
But it isn't the cold feed that is likely to be the determining factor? The hot water is tank storage and there is only about 3 metres of head for the hot tank,at best.
And I am still curious as to why manufacturers would even make bath taps/fillers with 15mm rather than 22mm inputs.