hot water radiator construction

Mike T., Swampeast MO

If you don't have the rods, the sections are joined by threaded nipples. It's practically impossible to disassemble such rads.

If push nipples were used without the threaded rods to hold the rad together, the water pressure would simply pop them apart.

Pete Scozzare

cast iron radiator construction for section removal

Recently I read a Q&A by Dan Holohan on this subject. Specifically he said that you can differentiate a radiator which was put together by push nipples v. threaded nipples because of the threaded rod holding the sections together. For two years I have been on-and-off trying to repair leaks in 5 radiators in a hot water system in an old house I am renovating. I too discovered J-B Weld and have had much success. But there is one hold out radiator which won’t let me find all the tiny little leaks, and I mean tiny, so I was intrigued by the possibility of removing the suspect section in this radiator. Although I am an expert in leak detection of underground storage tanks and piping, radiators and their construction are not my specialties. My radiator has two inlets, one on top & one on bottom. There are no threaded rods and zero clearance between each section where they are joined together. My gut tells me that these are joined by push nipples but without the threaded rod and with little knowledge of radiators I need to be sure before I start trying to pry the sections apart. Thank you for taking the time to assist me in this endeavor. Pete Scozzare

Pete Scozzare

No Rods & No Evidence of Welding

I understand what your saying but they have to be unthreaded nipples because there is no rod and no space as would be apparent with a threaded nipple. There is no place to put a pipe wrench unless it is paper thin. Also no evidence of any welding either.

Mike T., Swampeast MO

The nipples have lands (raised strips) on their inside with the outside threaded. The lands engaged grooves in a special wrench (essentially a long spud wrench with a thin neck) that was inserted through the connection holes. It's this assembly method that makes them a practical impossibility to disassemble.

After being in service for decades the lands rust somewhat. Even if you could find (or have made) a proper wrench, it will almost certainly just shear off the lands before ever turning the nipple. They have to be cut and/or ground out without harming the female threads in the radiator sections. Time-consuming but still reasonably easy for an end plug, but truly AWFUL for the nipples--I know as I tried it once. NEVER again! Remotely possible if the only leak is in the section right against the end, but if further in you have to remove each and every section individually until you get to the leaker.

Mike T., Swampeast MO

See this document from Burnham

Same principle if somewhat different nipples and assembly tool. I'm not positive but I don't believe that gaskets were used in most of the originals. Am almost certain that at least one manufacturer (American Radiator?) bragged of a "perfect" assembly method without gaskets.