Pipe Size

[adamjseed]

Hi,

I'll start off by saying I'm not a plumber but keen DIY'er. I am in need of replacing all the Rad's in my house as they are about to burst. They all have a corroded spot at the top. At the same time I think its best to replace the pipe work incase the whole system is rusted from the inside out.

While I am going to use a plumber for the main bits of work I am considering doing a lot of grunt work myself, mainly re piping all the rads and fitting new rads.

I want to install a multi zone system - ideally each room is connected to a manifold individually and would have their own room stats. So my first question is around that. I get lots of different opinion on this.

Q1, Given the opportunity and not considering cost/effort would it not be a good idea to plum each room on its own circuit, or would it be better to just do upstairs/downstairs.

Q2, If so what pipe size should be used? Presumably on a standard ring would have a larger standard pipe then each spur is smaller.

Q3, I plan on using speed fix for under the floors but use copper where visible. Is this sensible?

Thanks for any help.

 

[oldbuffer]

More information on the size of installation would be useful. How many rooms / radiators, how many floors etc. But assuming a three bedroom semi, I'd say:

Q1 Zoning by room doesn't give you much benefit that you can't get from a TRV on each radiator. If you really want it stick to a normal layout but get something like the Honeywell EVOHome system for zoning. Upstairs / downstairs is relatively simple to achieve and worthwhile if re-piping anyway.

Q2 Very dependent on size / length of runs. In many cases 22mm backbone with 15mm feeds to each radiator is ample. If bigger perhaps 28mm to start of each zone then 22mm zone backbone then 15mm radiator feeds. If using manifolds you can go down to microbore but I personally don't like it. However, it does give you the option of bring the radiator tails out behind the radiator.

Q3 JG Speedfit or Hep2O are fine but must be installed and TESTED in accordance with manufacturers instructions. This requires a test pump, which can be hired, I think. When testing make sure no radiator, boiler or other device working pressures are exceeded. If they would be then isolate / bypass them.

Don't forget that if you do the pipe work, the boiler installer won't accept responsibility for leaks or poor performance owing to radiator (mis)sizing or the like.