plumbing immersion heater with 15mm

[jpadie]

hello all

i've got a 120L unvented cylinder with immersion elements that has 22mm feeds.  the instructions for plumbing it in are ambiguous but the preference is to have 22mm pipe work.  It does say that 15mm is satisfactory if the mains pressure is ok.  

 

what's the best way to do this?  is it to go from 15 to 22 where the cold comes in and then plumb the security group and cold feed in 22mm?  and idem the hot outlet: go from 22mm to a 22mmT and then to two reductions to 15mm?

 

thanks.

 

[JohnMo]

You do realise you need to be qualified/competent to plumb in an unvented cylinder?

 

Are you using the cold water feed from the inlet group? If not you need pressure control valve near the stop cock and a check valve at the cylinder hot water outlet to prevent back feed to the cylinder.

[jpadie]

This is for a garden room.  There are pressure limiting valves in the system before the cold leaves the main house.  

 

The immersion is mainly for the shower.  The shower cold water feed comes from the balanced cold on the inlet group.  The inlet group has an nrv and a 3bar pressure limiting valve as well as an outlet for the expansion vessel.

 

 

[JohnMo]

22 - 15 - 15 reducing tee for the hot, 15 - 22 reducer for the cold.

 

You still need to be qualified to certify the installation, many plumbers don't like to certify self installation, unless organised before hand.