Unused legs in a central heating system?

Apologies for the rather cryptic title...
I am in the middle of creating an open-plan kitchen/lounge/dining area and cannot with certainty decide where best to put the radiators. Indeed, I can envisage that the 'best' position might well change over time if/when the more mobile elements of the room move around.
I was wondering, therefore, if there would be any issue with me piping up a couple of areas to cater for the potential alternative siting of radiators at a later date? In keeping with the rest of the system I'll be using 10mm plastic piping run down from the ceiling behind the plasterboard so it'll be a straightforward job to do at this stage of the construction (the ceili ng is currently down). The exit points are are at socket height (behind whe re the radiator would be) so I would just cap off the pipes in a back box a nd cover them with a blanking plate.
Once my project is complete there will be limited access to the ceiling spa ce so I was planning on connecting all the radiator feeds up to the ma nifolds now hence the unused ones will likely be sitting there for a long t ime with either air or water in them. Does anyone anticipate any potential issue(s) with this?
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From my experience with microbore systems dropped from above is their tende ncy to develop airlocks particularly after a drain down. Most can be solved by having sufficient drain off points one on every radiator. If you plan t o leave pipes accessible behind blanking plates then providing drain offs s hould allow you to ensure all air is removed, once fully filled any air get ting into the system should tend to collect in the tops of radiators.
Richard
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On Friday, 13 September 2019 09:56:49 UTC+1, Tricky Dicky wrote:

dency to develop airlocks particularly after a drain down. Most can be solv ed by having sufficient drain off points one on every radiator. If you plan to leave pipes accessible behind blanking plates then providing drain offs should allow you to ensure all air is removed, once fully filled any air g etting into the system should tend to collect in the tops of radiators.

Thanks Richard, that's good to hear (the drain off mitigation, not the risk !). All the existing radiators do happen to be fitted with drain off valves so perhaps the risk was recognised at the original design/installation sta ge also.
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On Friday, 13 September 2019 09:45:22 UTC+1, Mathew Newton wrote:

d cannot with certainty decide where best to put the radiators. Indeed, I c an envisage that the 'best' position might well change over time if/when th e more mobile elements of the room move around.

a couple of areas to cater for the potential alternative siting of radiato rs at a later date? In keeping with the rest of the system I'll be using 10 mm plastic piping run down from the ceiling behind the plasterboard so it'l l be a straightforward job to do at this stage of the construction (the cei ling is currently down). The exit points are are at socket height (behind w here the radiator would be) so I would just cap off the pipes in a back box and cover them with a blanking plate.

pace so I was planning on connecting all the radiator feeds up to the manifolds now hence the unused ones will likely be sitting there for a long time with either air or water in them. Does anyone anticipate any potentia l issue(s) with this?
This is where underfloor heating comes in. No radiators.
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On Friday, 13 September 2019 18:24:29 UTC+1, harry wrote:

Indeed, but it's a bit late for that now! ;-)
Whilst part of the new space was a new extension (and hence easily UFHable) the remainder wasn't and there were various reasons I wasn't keen on retrofitting it.
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On Friday, 13 September 2019 18:24:29 UTC+1, harry wrote:

and cannot with certainty decide where best to put the radiators. Indeed, I can envisage that the 'best' position might well change over time if/when the more mobile elements of the room move around.

up a couple of areas to cater for the potential alternative siting of radia tors at a later date? In keeping with the rest of the system I'll be using 10mm plastic piping run down from the ceiling behind the plasterboard so it 'll be a straightforward job to do at this stage of the construction (the c eiling is currently down). The exit points are are at socket height (behind where the radiator would be) so I would just cap off the pipes in a back b ox and cover them with a blanking plate.

space so I was planning on connecting all the radiator feeds up to th e manifolds now hence the unused ones will likely be sitting there for a lo ng time with either air or water in them. Does anyone anticipate any potent ial issue(s) with this?

There are people who cannot tolerate underfloor heating. It isn't the answe r to everything.
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On Friday, 13 September 2019 09:45:22 UTC+1, Mathew Newton wrote:

d cannot with certainty decide where best to put the radiators. Indeed, I c an envisage that the 'best' position might well change over time if/when th e more mobile elements of the room move around.

a couple of areas to cater for the potential alternative siting of radiato rs at a later date? In keeping with the rest of the system I'll be using 10 mm plastic piping run down from the ceiling behind the plasterboard so it'l l be a straightforward job to do at this stage of the construction (the cei ling is currently down). The exit points are are at socket height (behind w here the radiator would be) so I would just cap off the pipes in a back box and cover them with a blanking plate.

pace so I was planning on connecting all the radiator feeds up to the manifolds now hence the unused ones will likely be sitting there for a long time with either air or water in them. Does anyone anticipate any potentia l issue(s) with this?
It can be an issue if you get an infection in the system, or other situatio n where it's necessary to empty the water in the legs. Put a drain down val ve on the end and all is good.
NT
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On Friday, 13 September 2019 19:24:28 UTC+1, snipped-for-privacy@gmail.com wrote:

Hmm... infection doesn't sound good. Is that something inhibitor is design to prevent? (Of course this needs water in the legs, not air)

The pushfit stopends should serve well for that, and being 10mm fittings they are tiny so will easily fit within the standard backbox.
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On Friday, 13 September 2019 21:09:02 UTC+1, Mathew Newton wrote:

it doesn't prevent it

?
sounds good
NT
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On Saturday, 14 September 2019 01:41:44 UTC+1, snipped-for-privacy@gmail.com wrote:

I meant if the inhibitor is to have any effect then the pipes will need to have it in them, not air.
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On Saturday, 14 September 2019 10:37:16 UTC+1, Mathew Newton wrote:

afaik there is no purpose in having inhibitor in plastic pipes - they don't rust!
NT
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On Saturday, 14 September 2019 12:05:20 UTC+1, snipped-for-privacy@gmail.com wrote:

It's to protect the radiators rather than the pipework.
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On Saturday, 14 September 2019 17:21:37 UTC+1, Mathew Newton wrote:

and any other parts that might rust, eg boiler & sometimes other parts. Doesn't do a thing for plastic.
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On 13/09/2019 09:45, Mathew Newton wrote:

The unused legs would be better filled with water rather than air. How about connecting each flow and return together through an isolator valve behind the blanking plate? You could then allow them to fill with water and then turn off the valves.
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On Friday, 13 September 2019 19:32:57 UTC+1, Roger Mills wrote:

I could always bleed the pipes by briefly removing the stop ends. That's on e of the beauties of push-fit for me; the ease with which joins can be made /unmade. I've done many a 'live' capping using push-fit stop ends and when the pressure's on (pun intended) you can't beat a toolless fitting.
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Yes when I saw the subject line I did wonder who would put wooden legs in an expansion tank!
I did consider it might be in preparation for Talk like a Pirate day on Thursday... Brian
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