replacing TRV - removing old adapter from radiator

[sm_jamieson]

I've removed the TRV from the radiator down-pipe and the adapter that connects the radiator itself to the TRV. I'm left with the radiator with adapter attached. The adapter has a captive nut that was used to connect to the TRV body. The adapter is the same finish as the old TRV and was obviously supplied with it. This adapter converts to 3/4 BSP which suited the old TRV. The new TRV is supplied with an adapter converting the radiator to 1/2 BSP which suits the new TRV. So I have to remove the old adapter. This is the tricky part. The old adaptor appears to have no cut-outs or shaping whatever to take a spanner. It is totally smooth with only about 3mm between the rediator casting and the captive nut. I cannot see how it can possibly be removed. Attach something else to it, and use that to unscrew it ? How can I get this adpater off ? Thanks, Simon.

[Stuart]

Did you look at the fitting internally .Does it not have a hexagonal (?) inner to take a VERY large Allen key type spanner .??

Stuart

[Cicero]

=============== Look inside - probably shaped for an allen key.

Cic.

[Roger Mills (aka Set Square)]

If you're talking about the "tail" (the bit which screws into the radiator) it will almost certainly have a hexagonal hole inside, and requires an appropriately sized Allen key to turn it.

[sm_jamieson]

I did wonder about that. I tried to look into the hole, but not very far. I will try some allen keys of various sizes and see if they engage. Cheers, Simon.

[Stuart]

It is a BIG one specially made for removing such fittings .

[Sponix]

Some have a couple of ridges on the inside I believe, instead of a hex shape.

You can buy a large hex key from most DIY shops for about £3 which will do all types of fitting.

sponix

[sm_jamieson]

Got a proper radiator key from the plumbing supplies. The square end did it, and there was loads of play when reversing direction (just to test it), so it's probably one with the ridges. Bonus, the new TRV fits perfectly, which surprised me. Success. Cheers, Simon.

[Dave Plowman (News)]

The sheds etc sell the correct one for pennies that also has a square drive for tightening bleed nipple units. They're a bit larger than usually comes in those sets.