Added a new radiator to extension but its not getting any flow.

[Jimmy3645]

Recently had a small extension fitted to our house and I’ve fitted a new radiator in the room. Our central heating system is pretty modern with a distributor upstairs and one downside, each radiator is fed individually by 16mm underfloor heating pipes. There's a radiator in the room against the new extension so the new radiator is just the other side of the wall. What I have done is taken the feed from the old radiator and put it into the new radiator, with the return from the new radiator going into the old radiator then the return from that going back into the distributor. I figured the old radiator wouldn’t heat up very quickly but its a small room in the middle of the house and it really wouldn’t matter (more important to have the new radiator in the extension heating up well)
But turns out I’m getting almost no flow whatsoever… Ive tried turning down the flow to all of the other radiators at the distributors to force flow into the new radiator, this definitely helps and it will eventually heat up but its still extremely slow. Ive checked thermostats, valves air locks etc etc, there’s obviously something I’ve done wrong, or putting 2 rads together on this system simply doesn’t work?
Any help much appreciated.
Thanks

 

[MagicDoughnut]

Probably airlocked or you dropped rubbish in the pipe during install. Full drain down, close all radiators and fill the new one first. Open each valve at a time to ensure the radiator is filling from both valves. Is there water is the new radiators? If it heats up very slowly with the rest shut off that indicates an airlock. Heat can transfer without flow.

 

[Jimmy3645]

Thanks very much…. Yes the new radiator seems to be full of water. It appears to be all bled up ive had the bleed screws off completely etc The feed pipe is hot straight away and the TRV gets very hot but thats the end of it. ( I have removed the TRV and replaced it with a straight piece of pipe just to be sure…. But the problem is the same). When I’ve turned all the radiators off to force water through the new rad you can hear the water trying to get through the distributor anywhere it can but still doesn’t get to the new rad. It really does act as if one of the pipes is blocked. thanks again

 

[MagicDoughnut]

Is the lockshield open?

 

[terryplumb]

Distributer ?
16mm pipes ?
You appear to have altered the plumbing incorrectly.

 

[Jimmy3645]

Lockshields open yes

 

[cross thread]

Photos of what you have done include rad and the tee in position

 

[Jimmy3645]

 

[Jimmy3645]

This is how it was, and how it is now. I haven’t Tee’d into the old feed because I wanted to give the new radiator priority.

 

[oldbutnotdead]

Not going to work all that well. Because you have plumbed the 2 rads in series, each valve restricts the flow to BOTH rads. So if you switch the old rad off, no flow to new rad. If you wind down the lockshield on either rad it restricts the flow to both rads.
Do it again- tee off the flow and return for the old rad to give you flow and return for the new one.
If your 'distributor' is a UFH manifold with control for each leg you'll need to adjust that leg to give adequate flow for 2 rads.

 

[cross thread]

With that set up if one rad is off they are both off

 

[Jimmy3645]

I will absolutely do this thanks…. but cant see how it will fix my problem, Neither radiators are working even with both TRVs fully open and both lockshields open, even with all other radiators shut off at the manifold.

 

[oldbutnotdead]

When you fitted the new rad did you drain the whole system or just that circuit from the manifold? There's an airlock somewhere, rad bleed valves on their own are often inadequate to shift a pipe bubble (you need a bit more flow. On modern rads you can remove the blanking plug at the top and fit a temporary full bore bleed valve, with a pressurised system you'll need a friend at the boiler to keep the filling loop open). Obviously turn both rad valves off & vent from bleed valve BEFORE removing blank plug...

Edit UFH manifolds can be picky on the whole priming/bleeding/venting sequence...

 

[Jimmy3645]

Got it thanks very much….. I only drained this circuit… I will drain it and set up a hose from the top drain plug outside or something

 

[cross thread]

was the existing rad working before you added the new one ?
are you sure you have a flow and return off the manifold and not two feeds from the flow