UK Plumber Forum

[david1949]

Help needed please I have a 30i Combi gas boiler in my loft the 22mm flow and return coming from the boiler runs along the loft and down the outside wall of the bungalow and back into the house under the bedroom concrete floor. Could I cut this 22mm flow and return pipework about 6 feet from the boiler in the loft and reduce to 15mm run it down the inside kitchen wall and into the 15mm pipework going to the kitchen radiator and then fit 2 blanks on the 22mm pipework outside as i do not want to lift part of the concrete in the bedroom floor to get at this flow and return . I am hoping that doing this will make the heat up quicker at start up time.

[jonnyswamp]

Are these 22mm pipes insulated and boxed in ?

[REDSAW]

hi David and welcome.

quite frankly this sounds a right botch install to have the pipes running on the outside and not internally boxed in. or do you live in spain or somewhere warm?

in theory, yes you could do that however:
its not a good idea to have too long dead legs left on the 22mm cut off.
the heating out put depends on how well your system is set up to run 15mm from boiler.
15mm feeds restrict the ballance to each rad and you may have output ballancing problems to each room due to restricted bore.
in theory, yes the combi can push through any pipe diameter down to 8mm but again, its the hydraulic pressure differential that may cause problems.
you could link the 2-pipes feed and return into each other to make a circuit and add a drain-off point to it which is a good idea, then insulate and box it in.
is it a worcester bosch greenstar 30i or glowworm 30 cxi?

hope that helps.