Planning to move cylinder, new pipe size?

[Greenbeast]

I'm planning to move my DHW cylinder from a first floor bedroom to a ground floor bathroom.
I intend to take the pipework from the exiting location up through the roof and down again.

It is currently a gravity hot water loop and pumped CH, but obviously i'll be moving to fully pumped (S-Plan).

Does the Hot water loop need to be 28mm all the way through the house?
The reason i ask is two-fold, obviously 28mm pipe and fittings are more expensive but also at some point i intend to replace the boiler and site the new one next to the cylinder, in this instance i'd like to re-use the pipework i'm installing now to plumb the boiler into the CH circuit.

The Current boiler is an ancient thing rated at 15kW (i believe)

Current System

Proposed new layout

Thanks for any help[/img]

 

[Deleted member 2053]

'Hot water loop' is ambiguous. If by that you mean the primary feed from the boiler to the cylinder then on gravity it used to be 28mm but it is more common the use 22mm on a pumped system. However the length of the pipework is a factor and you need to be sure that the resistance from the pipework does not exceed the pressure head avaiable from the cirulator. There are tables on the web that will give pipe size/length/water volume figures. Be sure to make provision to bleed air from the pipework. The amount you can push out with a domestic circulator is very limited.

 

[Greenbeast]

yeah sorry my terminology leaves a lot to be desired.

Thanks for your help

 

[heat24seven]

Is that new cylinder unvented , because i dont see a vent pipe on your diamgrams , if it unvented make sure your up to scratch on all the regs , if its vented make sure youve got your vent pipe or youve got bomb on your hands

 

[buffy27]

stainless steel cylinder.possible extream temps /pressures. u cannot use a copper cylinder or an open vented f & e set up. end of story the system will win the arguement if there are problems

 

[Greenbeast]

Its open-vented and not Unvented.

Yes sorry the diagrm is missing an expansion pipe from the cylinder

 

[buffy27]

i have not ever installed solar on an open vented dhw system.in ireland it is illegal.heard it beihg done with the addition of a heat dump.i would not condone this though.have i picked u up wrong?

 

[Greenbeast]

yeah i think you've mis-understood, as it is common practice over here (from the research i've done)

Think of a normal open-vented system with an extra coil in the cylinder for the solar loop. The solar loop itself is pressurised (panel is higher than tank in most cases)