Syphoning problem with column radiator on single pipe system

[Canyondust]

Hi.
I have recently replaced a single panel radiator (without any fins) of size approximately 1200 x 600. This radiator is within the family bathroom and connected to a single pipe system. The pipe size is approximately 2 1/2" steel design. This radiator is the first on the loop and connected to an indirect gas boiler (so not a combi).

I have replaced this with a more modern, column radiator of similar size. The radiator from my understanding has a baffle in the base, approximately 6" away from the inlet. The fitting instructions were specific about which port was the inlet and outlet to which I have followed. The inlet has a thermostatic valve (a type which can be altered to allow fitting upon either an inlet or outlet) and the outlet has a flow valve.

The original radiator worked perfectly, with no issues. The new one however will not heat up at all.

My concerns are that the inlet port and outlet port (due to the large single pipe) are at very similar temperatures and thus not allowing any thermosyphoning - but that doesnt help me understand how the previous radiator worked.

Any ideas would be gladly welcomed.

Regards in advance.

James.

 

[lame plumber]

i would think the column rad needs the outlet lock shield opening more, plus the fact modern column rads are rubbish heat emitters compared to a standard finned rad, so wont work well at all on a single pipe system.

 

[Whyme]

Is the trv suitable for single pipe because standard ones are smaller bore and compatible ones are about 30 quid each..??