Fitting TRV\\\'s

I have just bought some TRV's for fitting into bedroom radiators. These come with a union or tailpiece that needs to fit directly into the radiator i.e. fits between TRV and radiator. This has flats on it so you can get a wrench onto it. However the union already present on the radiators are round, no flats, and the gap between the body of the radiator and the nut it too small/narrow to get any tool I know of in there. How do I remove this union/tailpiece?

Ian

Do you need to remove it? If the threads are the same, valves can usually be screwed on, and you chuck away the unwanted new bits.

You need to get a rad spanner, fits inside the part you need to remove and unscrews, looks like a large allen key.

Thanks BDL - that was the answer . Never thought to look inside the tailpiece to see if there were flats - damn clever these engineers!

Oilman - unfortunately the diameter of the existing piece is larger than the ones on the TRV's I bought so they have to be replaced (or else I would have fitted them by now )

Thanks again for the replies,

Ian