Why won't nut 'catch' thread of rad valve?

[potato80]

Hi all.

Replacing old rad valves with TRVs.

Two of them I'm struggling to get the nut on the pipe to 'catch' the threads of the new valve. It seems to be 1 or 2mm away from the threads, so can't screw it on.

Anyone else know what to do in this scenario, please?

I thought maybe the inside of the old nut is a bit grimey, but having cleaned it out its still not catching. Feels more 'positional'; almost as if the olive is a mm or 2 too low

I thought you could just screw it on, but apparently not!

Thank you!

 

[denso13]

Pipe looks too long. Can you cut perhaps 5mm off the end, leaving the olive where it is?

 

[potato80]

Pipe looks too long. Can you cut perhaps 5mm off the end, leaving the olive where it is?

Ah, that would make sense as no matter how much I squeeze them together, I can't seem to get a decent grip on the nut.

Yeah I can cut the pipe a little bit at a time and see if that works.

I assume you'd just use a ratchet cutter or one of the circular ones?

 

[denso13]

Pipe slice might foul on the olive, hacksaw might be better. Whatever works though.

 

[Mottie]

Put a 15mm open ended spanner under the nut and tap the nut and olive upwards. Use perhaps another spanner to tap, rather than a hammer - you want something light to tap with.

 

[Madrab]

Old valve had a higher pipe stop inside so when fully home the olive sat lower on the pipe. If it has been tightened right up with the old valve before then it won't move, no matter how much tightening.

As suggested you need to cut about 3-5mm off the end of the pipe, then use a wrap of gas PTFE tape on the olive (or 3 if water tape) if using the old nut and olive. Dremel + cutting blade would be the ideal.

 

[Johntheo5]

Ah, that would make sense as no matter how much I squeeze them together, I can't seem to get a decent grip on the nut.

Yeah I can cut the pipe a little bit at a time and see if that works.

I assume you'd just use a ratchet cutter or one of the circular ones?

Post a photo of the pipe removed from the valve, you only need the pipe end to extend 4 or 5 mm or less beyond the olive as its now compressed.

 

[kidgreen61]

As said above, just tap the olive further up the pipe