CH install - New Rads not heating - Need your help please

Terry - Just the standard types.

Chris - That's very helpful, thank you. I'm hoping using the pictures you've attached, I'll now be able to compare and send a few photos to you guys to examine. Hopefully we'll get to the bottom of this problem.

Gasguru - Thanks - From looking at all my radiator TRVs, they have an arrow pointing downwards (towards the pipe). Does that tell you which one I have?

Thanks again guys.
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Can you confirm ,if you turn ALL other radiators TRV ' s FULLY OFF ,and turn boiler /central heating on , that the loft radiators show no signs of heating whatsoever ,left running for half an hour ?
Can you confirm ,if you turn ALL other radiators TRV ' s FULLY OFF ,and turn boiler /central heating on , that the loft radiators show no signs of heating whatsoever ,left running for half an hour ?

Just for the sake of diagnostics, I'll do this again following what you've said. But just to clarify, do I need to also close off the shield valves or do I leave them alone/open?
Just fully close TRV on every other rad. Don't touch the lockshields.
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Okay, thanks terry. One more question - The hallway radiator doesn't have any TRV i.e. both look like lockshield valves, so what do I do there?
Close one of the valves ,and count how many turns it takes ( so you can return it to its original position when finished test) to close turn clockwise till it won't turn any further.
Brilliant! Thanks ever so much. I won't be able to do this right now due to little one being asleep and I can't enter the room. I'll start on this first thing in morning.

Speak tomorrow. Bye!
Really sorry for replying again. I was about to call it a night, but curiosity got the better of me.

You said that I check whether the attic radiators get hot when I close the TRV valves. But what happens after that? what would I need to do depending on if they are cold, slightly hot or really hot?

It's just that your instructions would allow me to do multiple tasks in one go rather than having to wait for another reply.

If the attic rads start to heat up well ,you have a balancing issue.
If they do not heat at all ,plumbing issue as already advised ,no FLOW ,incorrect connections to flow and return pipework.
Have you checked that the system is filled up and pressurised to the correct level via the filling loop? 1.5bar when cold.
Reg.Gasman - Air lock would mean knocking noise or there would be air coming out from radiators instead of water. I've bled them starting from closest to boiler downstairs and working towards the furtherest upstairs - no air or noise - just water.

dilalio - Yes - On cold it's just slightly over 1.6bars.
Air lock will not cause knocking in CH and radiators will be full of water as normal. If you have a long run of horizontal pipe (eg accross a room) you get a bubble of air trapped at a slightly high point. The radiators etc still get filled via the other pipe but the air locked pipe prevents circulation as water cannot get past the air bubble. Usually if you turn all the other radiators off and force all the flow through the problem area, the air bubble gets forced out. Turning the CH pump to full speed also helps. In an extreme case other measures are required.

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