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Central Heating Pipe Alteration and Routing

Postby sjwomersley » Fri Jun 28, 2019 9:31 am


I'm not a professional but I like to think I'm a competent DIYer (nothing has blown up or flooded yet!) and in the process of slowly refurbishing my Victorian terrace house in Yorkshire. My main objective for this year is to deal with my plumbing as it's been done badly in the past and now we have a combination of redundant pipes all over the place and badly routed pipes almost everywhere!

I have a Vokera Easi-Heat Plus 25C combi-boiler in my cellar. It supplies:

1x radiator in the cellar (on it's own branch)
3x radiators on the ground floor (1x on it's own branch, 2x sharing the same branch)
3x radiators on the first floor (all sharing the same branch)

The flow and return pipes connected to the boiler are 22mm copper and run about 4m across the cellar ceiling before being reduced to 15mm copper everywhere else.

At the moment a lot of the pipes have been installed in inconvenient places so I intend to replace them with JG Speedfit plastic pipes and re-route them slightly. My questions are:

1) How much of my system needs to be in 22mm and how much 15mm plastic can I use?
2) Do the connections to my boiler need to be in copper or can they be replaced with plastic too?
3) As we plan on replacing most of the radiators over time (budget restrictions mean we can't do it all at once) is it a good idea to install isolator valves on the flow and return side of every radiator before the lockshield and TRV, so that I don't have to drain down the whole system when I get round to replacing each radiator?

I want to make my system as efficient as possible so will be insulating all the pipes where possible. I've been advised that plastic pipes are more energy efficient than copper.

Thanks in advance!

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Simply Build It

Postby htg engineer » Fri Jun 28, 2019 8:17 pm

Most manufacturers require at least the 1st metre off the boiler is copper.

You don't want to restrict the flow too much, it's best to run as far as you can in 22mm and branch off for each radiator with 15mm. A short 15mm run will be okay for 2 radiators.

Isolation valves are handy if hidden under floors etc, but a place for a potential leak.
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