Two radiators not getting hot

[battyman]

I have this problem:

I had a leak on a fitting in the roof of my bungalow (new build 3 years old) on the central heating manifold (after the two way valve). All radiators were working but I was loosing pressure so I found the leak, drained the system, fixed the leak, re-filled/pressured the system, and now two radiators not heating at all.

I have checked the TRVs, all OK. When I bleed the radiators I get a hot water flow through the TRV but when I shut the bleed they just cool down and go back to being cold. All other radiators are working fine.

Do I need to balance the system? If so how? As it is a bungalow the radiator nearest the boiler is in fact a longer distance away pipe wise (due to the manic way the pipe-work is layed out in the roof (manifold feeding all radiators fairly central in the loft space).

Any help much appreciated.

 

[bengasman]

Probably needs balancing. Turn hot rads off, and see if the cold ones get hot.

 

[battyman]

Did that last night. Turned all working radiators off (at both TRV and outlet) no change to the two cold radiators, I left it like this for some hours, no change. Good pressure in the system, no air in system.

Oh and I did a bucket test on one of the radiators, both sides fine, good flow and flushed through the radiator aswell. Still no heat getting to them.

Did a balance on working radiators still to no effect.

Is it time to bite the bullet and call someone in?

 

[WabbitPoo]

When you say you have chacked the TRVs, how did you do that?

Are the pipes to the bottom of the rads hot? As you know TRVs can stick.

To clarify, are you saying that the water bled from the rad is hot but when you close the bleed vent, the rad cools down? If I have understood that then a TRV must be knackered, surely...

 

[battyman]

OK here's what I have done......

24hrs ago both rads working.
Fixed leak at manifold.
Now two rads not working.

Have bled both. Hot water comes into both rads through TRV but once bleed closed rad goes cold.

Have now done a 'bucket check' disconnected after TRV with it closed. Then opened TRV and hot water comes out (both checks I think prove TRV, maybe i'm wrong?). Have blown through both rads, reconnected, filled up, still the same. Oh have done bucket check at other side and it works fine.

Any ideas?

Oh and the pipes at the bottom of the rad (going into TRV are cold) but hot water comes through when I open bleed valve.

 

[WabbitPoo]

well I am not a plumber, so until one comes along,.....its as if both sides are connected to the same flow pipe or the same return, which clearly they are not. Interested to see the real answer.....