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Repair Packless Valves

nz Member Posts: 125
I have a lot of these Dunham packless valves around the house, and since they're ~81 years old, they leak. Not a ton, but you can hear the air/steam spit out of them - especially on a longer burn. Some of the valves have a handle (first pic), some have a mushroom style knob (second pic). I believe the mushroom knob-style are packless, but I'm not 100% certain.

While it isn't causing a major issue now, there are enough of them leaking (I have counted 7 so far) that I'm sure it doesn't help with keeping steam pressure up to around where it should be. Also, I can hear it in some of the bedrooms, so it's undesirable. I would also like to experiment eventually with making the system run in a vacuum in the future, so repairing/replacing these would be important prior to doing a vacuum conversion.

My questions are....

1) Are the mushroom knob-style packless valves? They are marked Dunham, see second pic.

2) Can you repair a packless valve?

3) If not repairable, should I buy new packed or packless valves? There are 6 non-original valves, they are all packed at this point. I'm not opposed to replacing them with packless if it's better in the long run, which is my understanding that they are.




  • Dave in QCA
    Dave in QCA Member Posts: 1,785
    Might be repairable

    I have had some success in repairing old valves of this type.  It was quite a few years ago and I actually used it on a hot water system, and it was completely tight.

    To repair, it is pretty much necessary to remove the valve and put a temporary cap on the line.  Put the valve in a good vise, and using proper wrenches, a little heat, and tapping with a hammer, disassemble the valve.  What I found was that by cleaning all of the interior mating surfaces with fine steel wool and then applying a little...(very little) high temperature plumbers grease, that everything went back together and worked like a charm.  Your valves with round knobs may be spring packed type, but still possibly repairable.  On the pack-less valves with levers, if the bellows has cracked and no longer has internal pressure, it can't be repaired.

    http://www.heatinghelp.com/files/articles/1821/dunham.pdf   Here is a link for some good information on Dunham parts and systems.  Valves are on page 6-10 or thereabouts.

    If you have to replace, any valve intended for steam is fine, but I would prefer to service the old valves if they were mine. 

    At any rate, the system must be totally tight if you are thinking about vacuum.
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
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