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How to cut & cap old unneeded radiator pipes

Our house is early 1900s and there is an old small radiator inside a kitchen cabinet that has been shut off for years, and I'd finally like to remove it. This is a hot water system. (The whole system is drained currently because I had to temporarily remove another rad.) This photo shows the supply & return pipes in the basement going directly up into the cabinet where the rad is:

I'm pessimistic about being able to unscrew the pipes, and was thinking it might be easier to cut the 2 verticals right below the floor, and cap them somehow. Does this make sense? Given the tight spot, what is the best way for an amateur to do this? Is there a better way?

BTW, I've looked at the rest of the heating pipes in the basement, and as best as I can tell, the pipes are not in "series", so I think no other rads would be affected by this operation.

Thanks in advance!

Re: How to cut & cap old unneeded radiator pipes

If they are not in series you might check down the line for a unionand start there.
Cutting the pipe is an option but to actually cap it you will need to thread the end of the cut pipe.


MLB Construction
Re: How to cut & cap old unneeded radiator pipes

whether or not it feeds other radiators, you have to cut both lines and connect them to each other to keep the loop going, if not, you'll have to remove the circulator pump that feeds just that radiator. in general, it can be very tricky unscrewing very old pipes, many times the threads are rusted through and can not be reused.

Re: How to cut & cap old unneeded radiator pipes


First refer to the High Performance piping diagrams at the site listed below to see how your supply/return piping lines are arranged & how the hot water flows thru the rad; on most boilers the MAIN SUPPLY PIPE is 1 1/2 to 3" & comes out of the top center of the boiler; the MAIN RETURN PIPE is approx the same size but returns the water from the rads to the lower side of the boiler to be heated again.

The large blue box in the piping diagrams below is the boiler; the red line is the hot water (supply line to the rad) coming from the boiler; the orange line is the cooled water return line going to the next rad (series loop) or back to the boiler, depending on the piping arrangement; most piping arrangements are series loop with piping going to & from each rad; monoflo/venturi piping should also be connected to each other if a rad is removed; if you have 2-pipe reverse return, or 2-pipe direct return, you don't have to connect the pipes together, just cap them.

Soak the union fittings at the rad in the cabinet and the other nearby unions with WD-40, Liquid Wrench, Rust Buster, PB Blaster, etc. & let it sit for several hours, or a day---then try to loosen the joints at the rad, & the several others, if no luck.

You should be able to loosen one of the supply line sprayed joints eventually and cap it off, or connect it to the return line.

If you have to cut the lines, there is large diameter hi temp PEX tubing at heating supply stores, or high temp Fernco fittings available at heating supply stores & plumbing supply stores to either cap the line, or connect the supply/return pipes to each other; if all else fails, you can use automotive radiator hose.

At the Google sites below, click onto "images for fernco fittings" and "images for pex tubing" to get a long list of pex & fernco products.


Re: How to cut & cap old unneeded radiator pipes

What you have is a two pipe system. You can cap the two lines the feed that radiator without affecting the rest of the system. As far as unscrewing the pipe, your best bet is to crack the fittings in the basement. They are cast iron fittings. Back up the fitting with something like a three pound hammer and hit the boss of the fitting on the opposite side of your backup hammer with a small hammer. It mat take a couple of good shots. The fitting will crack and at that point it will unscrew the fitting by hand.

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