Is microbore OK for combi

[pepper1]

Hi.

I need your expert advice. I am trying to get my old system boiler replaced with a combi. THe problem lies with the radiators. My current system is piped in microbore (8mm copper I think). One heating company has advised (stressed!) that i replace all the microbore pipe and radiators due to the increase in pressure from a combi. Another has said thats not true and the pipe and rads will be fine with just a flush, so that the system is clean for when the combi is installed.

Do i really need 15mm pipe and new radiators??

 

[Gasman1015]

No, unless you have a circulation problem with your existing pipe work.

 

[pepper1]

Thanks for your reply gasman1015. So how will they 'tap into' the microbore. Will they just reduce down from 22 to 15 to 8 or will they go 22 to 8mm straight away??

 

[namsag]

They will just connect onto the existing flow and returns before it reduces down.... If you have twin entry rad valves these will need changing to a valve on each side of the rad