Two new radiators off pair of existing 10mm plastic tails

[CoolhandPete]

Just had a new extension and had two (1kw) rads installed in new room.
The builder has connected the new rads to an existing rad's 10mm plastic pipe tails.

One of the new rads is 5m away from the other and this rad does not get warm let alone hot.

We have checked water is flowing through and vented the radiators.

My feeling is that 10mm plastic pipe is just not enough.

It would be extremely difficult to connect the two new rads back to the 22mm manifold.

So my question is:

If we swap out the 10mm plastic in the new extension to 15mm plastic will that make any difference or will the fact that it still has a couple of meters of 10mm between it and the 22m throttle it down?

Current set up is 4m (total) of 10mm (from 22mm) to existing rad then 10m (total) of 10mm to 2 new 1kw rads.

New set up would be 4m (total) of 10mm (from 22mm) to existing rad then 10m (total) of 15mm (or even 22mm) to 2 new 1kw rads.

Thanks.

 

[terryplumb]

3 rads ? what's the kw rating of original rad ?
10 mm plastic may not be sufficient. Try closing every other rads TRV ,except the 3 in question ,see what result is.

 

[gas112]

3 rads off ten mm no chance tell him to get it done right

 

[CoolhandPete]

3 rads ? what's the kw rating of original rad ?
10 mm plastic may not be sufficient. Try closing every other rads TRV ,except the 3 in question ,see what result is.

Original Rad is 0.8kw.

Try closing all rads but the furthest one of the new two never gets warm.

 

[CoolhandPete]

3 rads off ten mm no chance tell him to get it done right

As you may suspect unfortunately it's not that simple.

If we can't get to the main 22mm flow and return what would be "getting it done right"?

Thanks.

 

[ianmcd]

as @gas112 you will never run 3 rads from the origional 10mm pipes

 

[oldbutnotdead]

10mm placcie will deliver about 2kw max so no surprise your 2 new rads aren't working. If builder was aware of the 10mm tube at quote stage he's going to have to suck it up and take the hit to do it properly. If you can get 2 x 15 copper back to the 22mm they'll do 2 rads (or 3 that size) no problem. What's the extremely difficult- tiled concrete floor?

 

[CoolhandPete]

........
What's the extremely difficult- tiled concrete floor?

It's a relatively new build and it appears all the pipes are hidden in the walls.
I don't know how we could find them but even if we could the position of the new room would make it very difficult to get to the new rads wherever they.

I appreciate that may be what we have to do but thought it was worth exploring the option of increasing the pipe size from 10mm to 15mm first, hence my original question.

Thanks.

 

[oldbutnotdead]

Oh boo, new build so placcie threaded through noggins, joists etc. Can you access the 22mm where the 10mm tees off? If yes then you might get lucky by pulling 15mm through using the 10mm as a draw wire. High risk strategy (if the holes through timbers are only 12mm you'll be knackered) but mebbe worth a look- plan B is bang enough holes in the plasterboards to swap the pipes then reinstate with patches or full new boards, skim, done. Not a big or expensive job as part of a larger scheme- becomes an extra 2 hrs for dryliner and plasterer.

 

[FiremanT]

As you may suspect unfortunately it's not that simple.

If we can't get to the main 22mm flow and return what would be "getting it done right"?

Thanks.

 

[FiremanT]

It doesn’t really matter that it is “difficult “.

Tge job should never have been started - any competent would know it won’t work.
The only real solution is run the pipes back to the main circuit or manifold, or use an alternative heat source - electricity.

 

[CoolhandPete]

So the consensus is then that changing the 10mm to 15mm will not make any difference??

 

[ianmcd]

So the consensus is then that changing the 10mm to 15mm will not make any difference??

you can change it to anything you want it still wont work, you have to go back to the 22mm

 

[CoolhandPete]

you can change it to anything you want it still wont work, you have to go back to the 22mm

As we suspected then.

We are having a plumber round tomorrow to have a look and quote for a proper job.

Thanks to all for your constructive help.

 

[ianmcd]

To be honest, not a massive job for a good plumber/heating engineer, looks messy as plasterer or taper will usually be needed and redecoration, not as expensive as you might think, do it correct and do it once, dont faff about with work arounds