Options for flexible radiator plumbing?

Javelin · January 12

Hi Heating Pros,

I'm redoing my bathroom and in the past have had a hard time reconnecting the old iron pipe supply/returns to the radiator… As I re-do this bathroom, I would like to add some insulation in the old radiator alcove which means that the rad won't fall on the original positions… SO, I'm wondering what you would all do.

Obviously I plan on draining the system and them I'm wondering if I can keep some sort of rigid copper/metal piping from the radiator nipples DOWN through the floor, but once in the joist bay, I'm wondering if I can/should switch to PEX which will give me more flexibility and make the rad re-install easier when the time comes?

Is PEX A ok to use? or would I need the oxygen barrier kind? if oxygen, does it work/cut/crimp the same way as A which I'm familiar with?

What have/would you all do?

THANK YOU!

Jay

PS - existing iron pipe is 1" OUTSIDE diameter.. so 3/4" pex maybe?

Paul S_3 · January 12

Yes you would need to use oxygen barrier pex. Are those just standard cast iron tees in the picture? I see a patent date maybe like some older gravity system. I could be wrong

delcrossv · January 12

Looks like gravity scoop tees.

Jamie Hall · January 12

Me? I would figure out where the radiator was going to end up — I presume just a few inches, if that, further away from the wall? — and undo the existing pipe, cut the horizontals to the correct length, thread them up and put it all back together.

Steamhead · January 12

https://forum.heatinghelp.com/discussion/comment/1834142#Comment_1834142

https://forum.heatinghelp.com/discussion/comment/1834147#Comment_1834147

Those are probably "O.S." fittings, named for their inventor Oliver Slemmer.

Do not use PEX on this system. The fittings restrict the flow and the rad won't heat well. @Jamie Hall has the right idea.

hot_rod · January 12

Is that a plaster ceiling below?

If that is an outside wall, insulate the piping also.

Copper or pex may be easier for you to work with.

Figure out what those tees are, however. You want everything to work after you cover it up.

Javelin · January 13

Thank you all! Yes, a few things I forgot to include.. it's an old house (1911).. I took some better pictures of the fittings - looks like O/S on one side and "PATD FEB 1 98" (or maybe 95) on the other. 1898 :)

While the system (I think) has always been hot water (not steam), I do think it was gravity? based to begin with.. all the near boiler pipes in the basement slant a bit and are big fat cast iron.

Sounds like I SHOULD get my proper layout finalized, then re-do the correct horizontal lengths.. I was just looking to cheat a bit :) - and hopefully give a little more wiggle room through the eventual finished/tile floor.

HeatingHelp.com · January 13

Here are some resources:

https://heatinghelp.com/systems-help-center/the-o-s-fitting/

https://heatinghelp.com/systems-help-center/the-development-of-one-pipe-hot-water-heating-and-the-os-fitting/

https://youtu.be/7FKn_CFsrP8

EBEBRATT-Ed · January 13

Strip the old pipe back and replace it with copper pro press or sweat

DCContrarian · January 13

https://forum.heatinghelp.com/discussion/comment/1834464#Comment_1834464

Yep, I would have zero hesitation to take the iron pipe out back to a threaded fitting, as far as the closest O/S fitting (I wouldn't take that out). Then put in a threaded adapter and go from there with either copper or oxygen barrier PEX.

That iron pipe with the 1" outside diameter is 3/4" nominal size, 3/4" copper or PEX will have the same capacity.

Options for flexible radiator plumbing?

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