15mm central heating

Hi , the preferred method is copper pipe however it’s easier to instal plastic pipework wether that’s Hep2O or speed fit pipework - all adequate. You may find some parts of system are 22mm and tee off in 15mm. Hope that helps.

It’s also worth noting that plastic pipe work on heating systems seems to sludge up more than copper. Also, your circuits will need to be 22mm ideally as the flow is a little restricted due to the thicker wall of the plastic pipe. Personally, I always prefer to use copper, especially on heating systems.

I would recommend 22m pipe work from boiler to most of the radiators then use 15m pipe work to the last 2 radiators on heating circuit this way the radiators will heat up faster hopefully this will help

I would use plastic wherever possible, heat up is quicker , heat loss is less and most plastic pipes and fittings come with a long warranty. Cheers Jack