I have decided to replace my radiators and pipe work. This is partly for cosmetic reasons as the old rads and pipes look very tatty. Also system performance is not great with a few rads not heating up too well. I have some plumbing knowledge / experience but am by no means a professional. I'd like to use 22mm copper with 15mm flow / return to each rad but know this is going to be the most disruptive way to proceed and a lengthy job. So I've been considering barrier pipe and JG speedfit fittings, to make the job quicker and less disruptive. My present system uses microbore and 10mm plastic would be easiest I guess? Also should the 10mm go to the 4 port manifolds that JG supply or can I just T off the 22mm flow /return pipes. It struck me that with 6 rads on both floors I'll need a total off 8 of these manifolds. Also will plastic be cheaper than copper? What are the pro's and cons in terms of system performance? The other thing that I'm wondering is, does it matter how many times my flow and return pipes branch off into a T. I already have flow / return 22mm pipes on both floors that go to the existing microbore manifolds. If I use plastic JG manifolds, I want to run 22mm copper to these plastic manifolds and locate them under surfaces that will be carpeted rather than laminate floored, so I can get to them easily in the future should I need. I'd be really grateful for any help / advice from professionals and those with experience of similar projects. Thanks
To be honest, the problem you already have is likely to be caused by the 10mm microbore pipe. Microbore systems have to be carefully balanced which can be quite difficult even for the experienced installer. If the small bore pipe runs are long and flow pressure is low, you will continually have problems.
Problems with microbore can be exacerbated by sludge build up often found in open vented systems.
Frankly, and this is a personal opinion, but I would avoid plastic 10mm for these reasons and especially because the 10mm pipe inserts reduce the bore to a ridiculously minuscule size!
Use 22mm for the main feeds and drop down to a 15mm feed for each radiator. 15mm can feed a pair of rads but no more.
Use copper where the pipes will be visible and either plastic or copper for to your choice elsewhere. Speedfit is fine, but to be honest, I prefer Polyplumb as the fittings are smaller.
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