In the process of replacing a radiator and there is a fair amount of corrosion around the connections.

enter image description here enter image description here

I plan on scrubbing as much off as I can with sandpaper or steel wool, but is there a recommended way to clear corrosion here? Or does it even matter that much if I can tighten the fittings up enough and use PTFE tape?

  • Are you sure that isn't limescale? – RedGrittyBrick Feb 4 '18 at 18:12
  • @RedGrittyBrick - it could be. I didn't grow up in an area with limescale so have not encountered it previously. – Rory Alsop Feb 5 '18 at 11:41

The easiest way: change the valve, it will cost between 8£ and 20£, so you can pick up the the chance to put on a thermostatic valve and save on heating.

  • That would require skill above my current level, and I don't need a thermostatic valve on this radiator, so it would be overkill. – Rory Alsop Feb 4 '18 at 15:41
  • Fitting a valve is quite easy: just get the proper size (if you have copper/HDPE pipes), You still can install 'manual' knob on a therostatic-ready valve (just if you want to put thermostatic controller on in the future), replacing wit manual only today is a quite stupid choice (as valve prices are the same). You only have to close the main valves on the collector before replacing. It's a matter of 10 minutes. – DDS Feb 4 '18 at 15:55
  • I'm not likely to be able to drain the system down myself, so that counts as too difficult for me. – Rory Alsop Feb 4 '18 at 15:56
  • you won't have to drain the system: just close the main valves on collector of the floor you're working (and the system will be isulated, leading to no more than 1L drought) Then the procedure is identical that one you do to fill the radiator. If is a single story home, just close the water to the boiler and no need to drain the whole system, just purging air from the radiator you're working on. – DDS Feb 4 '18 at 16:01
  • many thanks. This is actually what I had to do in the end, as the fittings I had are an old size and unavailable. So I changed the valves and popped the new radiator on, refilled and pressurised, and it's all working perfectly! – Rory Alsop Feb 10 '18 at 15:13

You can clean the threads with a soft wire brush without being too aggressive and clean the tapered area very carefully with a very fine steel wool (not sandpaper), so as not to score the taper and cause a leak that can't be stopped. Make sure to clean both pieces, the one on the radiator and the one in the picture. If the tapered area is rough or deteriorated in any way, you could coat the tapered area with a thin coating of RTV silicone and tighten the union nut.Do not use teflon tape on the tapered area, use silicone only.


does it even matter that much if I can tighten the fittings up enough

It matters, the olive is compressed against that taper and that is what makes the watertight seal.

and use PTFE tape?

There are plenty of people who do slather on PTFE or joint-compound but you shouldn't really need PTFE tape on a compression fitting. Cleaning it up (as per d.george's answer) is the right thing to do.

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