newly installed rads never heat up, trv on wrong side

[BMW750i]

I have had 2 new rads installed in my extension they do not heat up at all; I am following instructions to balance the system, have found that 2 of the old rads have TRV fitted to the return side pipework, which are cold whilst lockshield is hot, my question is does it matter, the radiators do heat up afterall? Will it affect balancing?

My boiler is a Baxi combi 105HE, when previuosly trying to push heat into the new radiators I turned TRV's off every where else, but boiler would not fire up (pump ran) untill flow increased by opening another working radiator then it fired up. Although it would seem unlikely could it be the case that the new part is undersized, blocked or not piped the best way Tee'd off?

Your suggestions, tips on what to do are much appreciated

 

[Agile]

Call back whoever installed the new rads! Probably wrongly connected to the existing system. Builders are very good at doing that because they have no experience of plumbing.

Most current TRVs are bi-directional but if older ones are not and still working then thats no problem.

Tony

 

[BMW750i]

Thanks Tony,

I am waiting for the plumber to return. The new rads have been tee'd off the existing system rather than being cut in and extending the 'circuit', is that a likely cause in your opinion