I've just removed a radiator to tile the wall behind it. When I refitted it, before I opened the valves, I noticed a slight weep from the bottom of the valve where it fits on to the pipe coming up through the floor. I tightened it as much as I dared, but it is still weeping very very slightly. Is it ok to remove the bottom nut, while holding the joint together, and wrap some ptfe tape around the olive, and replace the nut without having to drain the system?? Also, is there anything I should use to help seal the connections from the rad to the valves as the joint is just metal to metal?
Try it - but the seal of the joint is between the rad valve and the olive not the olive and the nut.
Try tightening abit more, maybe you're being too cautious an extra turn may seal the joint, but you're right to be careful as you could squash the pipe if you overtighten.
It would be best to drop the system, remove the valve and examine the olive, maybe it has never tightened on properly. Sometimes you get abit movement on the olive - if there's any movement, remove the olive and replace. No movement - wrap PTFE tape around the olive and refit the valve.
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