DHW pipe sizing

[virgilns]

Unvented cylinder has 22mm inlet control group.

The outlet on my unvented cylinder is 3/4 bsp to 22mm copper or looks like 28mm copmpression fits straight on...the balanced cold is 22mm compression...

However, if i've got lots of bends and T's to get to the various outlets, is it worth me going straight up to 28mm on the balanced cold for the majority of T's and bends before the straighter runs in 22 to save on pressure drops....

I'm thinking 28mm on the hot, again to redue pressure losses...

 

[Mike2007]

Unvented cylinder has 22mm inlet control group.

The outlet on my unvented cylinder is 3/4 bsp to 22mm copper or looks like 28mm copmpression fits straight on...the balanced cold is 22mm compression...

However, if i've got lots of bends and T's to get to the various outlets, is it worth me going straight up to 28mm on the balanced cold for the majority of T's and bends before the straighter runs in 22 to save on pressure drops....

I'm thinking 28mm on the hot, again to redue pressure losses...

Why spend a fortune in 28mm copper use 22mm copper on the DHW and same on balanced cold (if possible, more likely 15mm)
If it turns out you cant balance the cold with the hot (ie supplied from the PR group), you should reduce at the mains entry.
For in my experience, the cold mains that might be 5 bar and DHW is 3 bar. Cold mains "bleeds" across mixing valves, into cylinders hot supply and cause cylinder to blow off precious hot water gradually!

 

[virgilns]

Why spend a fortune in 28mm copper use 22mm copper on the DHW and same on balanced cold (if possible, more likely 15mm)

To reduce preasure loss involving all the turns and Ts...the majority outside the 'boiler room' will be 22mm.

If it turns out you cant balance the cold with the hot (ie supplied from the PR group), you should reduce at the mains entry.
For in my experience, the cold mains that might be 5 bar and DHW is 3 bar. Cold mains "bleeds" across mixing valves, into cylinders hot supply and cause cylinder to blow off precious hot water gradually!

[/quote]

Can/will get ballanced feed to all locations, so no need to reduce at the mains.

Mains is 8 bar BTW

 

[mfarrow]

You shouldn't get loads of cold bleeding into the hot if there's a check valve on the cylinder inlet or combination valve, like there should be.