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Radiatior Valve Replacement (1920's Cast Iron)

Hi All,

I have previously drained and replaced several corroded parts of our hot water system, which uses 1920's cast iron radiators and 1-1.25" piping.

Several of the radiator valves are very old and are leaking from the stems - I am looking to replace them. I have seem similar jobs done before where the valve nut is cut with a hacksaw and released with a cold chisel, and the radiator spud is cut with a hacksaw and then folded for removal - new spud, union and valve etc.

However, the system we have does not appear to have any unions...

Any thoughts on how to replace the valves? I'm assuming I would have to replace the pipe coming out of the reducer on the radiator and add a union - then replace the valve.

Am I missing something obvious here?

(Note - this is the valve in the best condition with the least paint - the others are in bad shape)

Thanks all,


  • gerry gill
    gerry gill Member Posts: 3,078
    There is either a union or a left&right coupling and nipple below the floor someplace. You may or may not have the room for a standard valve with perhaps a male x female coupling holding the spud.
    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • Fred
    Fred Member Posts: 8,542
    Why replace the entire valve when you can put new packing around the stem (under that nut)?
  • Jamie Hall
    Jamie Hall Member Posts: 22,947
    Fred said:

    Why replace the entire valve when you can put new packing around the stem (under that nut)?

    Do try this before you go to the hassle of figuring out how to replace them.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • peterb01
    peterb01 Member Posts: 15
    Gerry - so the easiest approach to replacement would likely be to remove the pipe from the reducer on the radiator, replace with a shorter male-male section, then use a F-F coupler to attach to a threaded union on the replacement valve? The current threaded pipe length from the body of the radiator to the body of the valve is ~1.5" As you suggest, I'm not sure I have the space available to do this - and if I did this would need custom cut/threaded lengths?

    Fred - the picture I posted was of the best valve. Unfortunately some of the others have broken stems (knob just spins, or appears to work but doesn't actually shut off the water).

    Another option - would it be possible to remove and replace the stems? Not sure who makes the valves - here is a picture of the manufacturer logo:

    Thanks all!

  • neilc
    neilc Member Posts: 2,668
    is this hot water?
    looks like a steam trap in that second picture.
    known to beat dead horses
  • peterb01
    peterb01 Member Posts: 15
    Hot water (sorry - should have said that originally) :)
  • Steamhead
    Steamhead Member Posts: 16,734
    Try repacking them first, as @Fred and @Jamie Hall say. No reason to replace valves if repacking will work.

    If you do end up replacing valves, you'll find the nipple between the valve and the radiator is a "right-left" type with the standard right-hand threads at the radiator bur left-hand ones in the valve body. Modern valves have unions built into them, and you may need to extend the union tailpiece to make it long enough to reach the radiator.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • jsavage
    jsavage Member Posts: 42
    edited September 2019
    Some things I’ve learned recently from doing this in my own house:

    1) These were designed to work this way. You need some graphite or Teflon packing, which they sell at many hardware stores. Here’s a video: https://m.youtube.com/watch?v=daYfnVOvMWU. You have the same valves I have on my system... down to the wooden handles. Maybe everything will come apart easily, but i think it’s far easier and cheaper to repack the valves.

    2) When you put the packing nut back on, do NOT over-tighten it. I tore right through the top of the nut and have as of yet been unable to find a replacement.

    3) Some of the valves can be absolutely impossible to get off of the riser. At a minimum you want some PB B’Laster and a long wrench. I removed a radiator from my living room (added after initial system design). I have one 1 1/4” valve that will NOT come off. A 24” wrench was needed for some of them, but even that WITH a pipe over the end was not enough for the one I need to get off. Still stuck.

    4) This is probably not relevant for hot water, but I had some issues with the valves closing all the way on my steam system. I resolved this by removing the original cork gasket that sits on the underside of the bit attached to the handle and replacing it. Best method is to buy 4” x 4” red rubber gasket material at the hardware shop and cut it with an x-Acto knife to match the original gasket perfectly.
    Homeowner from Providence, RI
    Home b. 1897, one-pipe steam with a indirect gravity hot air system using Gold's pin radiators.
  • peterb01
    peterb01 Member Posts: 15
    Thanks all. A general question - is it an option to just replace the stems on the valves, rather than the entire valves? Several are broken (knob just spins, or looks like it's working but doesn't).
  • Fred
    Fred Member Posts: 8,542
    You won't find stems that match what is there. If you can get that large nut off you can pull the stem out and check to see if the disc may have come off of the end of the stem. If so, you can replace the disc. It may be a real challenge to get that nut to turn. The key is to repack around the stem. If the radiator heats, the valve is open and the valve actually serve no purpose, on a one pipe system, other than to shut the radiator off for service. On the very rare occasion that you need to service or replace a radiator, you can do that by simply shutting the system down.
  • peterb01
    peterb01 Member Posts: 15
    edited September 2019
    *Moved to new thread*