On 08/05/2015 20:39, Cursitor Doom wrote:
Hi all,

I'm putting in yet another radiator, but in this instance have been
unable to ascertain which pipes emerging from a wall are which. Given the
physical surroundings it's not possible to trace them back.
The rad I'm connecting up will have a plain valve at one side and a
thermostatic one on the other. I'm resigned to connecting it up both ways
in turn and seeing which works better. Is there a more scientific method,
though, and if not, how much difference in temp should I expect between
right way and wrong way?

Most TRVs allow for fitting on either of the flow or return.