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Cast Iron Radiator Connector Fitting

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by Eric Johnson, May 27, 2012.

  1. Eric Johnson

    Eric Johnson Mod Emeritus

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    I just picked up a couple of old cast iron radiators from a neighbor's "remuddling" project, and I'm trying to figure out how to use the standard connectors that they're plumbed with. In the past, I've simply removed these old brass fittings and installed standard black iron or copper fittings into the standard-thread bushings already in the rad, but since these are in good shape and it would be a lot less work just screwing a fitting into what's already there, I'd like to give that a try.

    However, they don't accommodate a standard 3/4-inch fitting. The threads are somewhere between 3/4" and 1". I read somewhere (I think) that I what I need are "angle unions" which, judging by most of the other radiators in my house, are a kind of special street 90. No clue where to score such a piece.

    Any thoughts? I plan to put 3/4-inch ball valves on these rads instead of conventional radiator-specific gate valves, so I need to reduce the line to a standard 3/4-inch pipe thread at some point.

    I can post pics, but won't unless somebody needs to see precisely what I'm talking about.

    These rads would replace HW baseboards in my mom's farmhouse, BTW, which I find to be pretty worthless and ugly, to boot. Nothing like a solid mass of cast iron and hot water on a cold winter morning to warm body and soul, IMO.

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  2. woodsmaster

    woodsmaster Minister of Fire

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    If you cant find anything to fit maybe you culd have a machine shop make somthing ?
  3. Eric Johnson

    Eric Johnson Mod Emeritus

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    Easier and cheaper just to remove the odd fittings and screw something standard into the standard bushing.
  4. Eric Johnson

    Eric Johnson Mod Emeritus

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    Here's what it looks like:

    [​IMG]

    This is what I think I need.
    [​IMG]

    And here's how I typically do it.

    [​IMG]
  5. slim

    slim Member

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    Replace copper piped baseboard with cast iron radiators? Rust?
  6. Eric Johnson

    Eric Johnson Mod Emeritus

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    Rust? Rust from where?
  7. salecker

    salecker Feeling the Heat

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    Hi Eric
    I was told that a ball valve may erode if its used to regulate flow.Havn't seen one that has eroded.
    Just thought i'd mention it.
    Thomas
  8. Clarkbug

    Clarkbug Minister of Fire

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    I think you are right on the fitting that you are looking for. I was given a few old radiators, and they had that same angle union fitting. I cant find anything that will mate up to it, so Im going to have to try and just back the old thing out and put in new bushings/fittings.
  9. Eric Johnson

    Eric Johnson Mod Emeritus

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    I've backed a few out and cut a few out. You can do a lot if you have a big enough wrench.
  10. raybonz

    raybonz Minister of Fire

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    Not trying to hijack but WOW Eric I haven't seen you here in eons! Welcome back!

    Ray
  11. Eric Johnson

    Eric Johnson Mod Emeritus

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    Thanks, Ray. I've been distracted by health issues, unfortunately. Not dead yet (but we're working on it).

    Anyway, I'm still cutting firewood and heating with same. Still fooling around with hydronic heating systems. I like the woodshed in your avatar, BTW.
    raybonz likes this.
  12. raybonz

    raybonz Minister of Fire

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    Well I hope you're on the mend Eric.. Thanx for the wood shelter comment! I just posted on another member's shelter which came out better and had a few improvements over this one.. Thinking a wood shelter picture area would be helpful to forum members that are thinking of building one..

    Ray
  13. Eric Johnson

    Eric Johnson Mod Emeritus

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  14. heaterman

    heaterman Minister of Fire

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    They do. I have about 100 pounds worth in a box in my shop, (going to melt them down to make a cannon ==c) None of them will close off completely because the bottom of the valve plate is worn off.

    A globe valve is best for throttling flow. A circuit setter is the ultimate but pricey.
  15. Eric Johnson

    Eric Johnson Mod Emeritus

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    Any idea why that would be? What's different between a hydronic line leading into our out of a cast iron radiator and any other location on the system? I've put ball valves on rads before, but I never use them to modulate the flow. It's more of a shutoff/isolation arrangement than anything else, though (to my mind) it certainly could be used to control heat output--probably even if the ball leaks..
  16. maple1

    maple1 Minister of Fire

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    I think the point is no matter where used (on a cast rad or not), the erosion will occur when a ball valve is used for throttling. They're not exactly designed for partially-open throttling, more for on/off. As I see it.
  17. Eric Johnson

    Eric Johnson Mod Emeritus

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    I see. That's ironic, given that one of the big advantages of ball valves is that you can see what they're set at from halfway across the room, vs. gate valves, etc., which need to be turned to figure out how they're set--and even then you're not completely sure, especially with older installations and those piped into fresh water systems and other applications prone to corrosion.

    Of course, if the ball is eroded, then I guess the handle location doesn't tell you as much about the valve as you'd like to think.
  18. flameretardant

    flameretardant Member

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    I got 15mm TRV's on my cast rads. It was impossible to find metric fittings/adapters so I had a machinist ream the valves to 5/8 inch. They were compression fittings so there is some leeway on fit. No leaks. And mixing copper and iron is a BAD idea. You WILL get corrosion. Fortunately, the cast rads can take a fair bit of corrosion. Hope you have a good sediment trap on your return.
  19. Eric Johnson

    Eric Johnson Mod Emeritus

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    Interesting point about dissimilar metals. Every house I've owned for the past 25 years or more has had hydronic heating systems mixing copper and cast iron, including my current setup which has a 54 year-old cast iron gas boiler extensively piped with copper. But I'm sure it wasn't originally. The one place I did own with all black iron (except for the brass valves, which I assume don't count) had a fine, black powder deposit on the inside of the pipes and rads and kind of a fishy smell. I'm trying to think what the other places' interior piping looked like, but I don't think they'd be considered rusty, at least to a noticeable degree. But the deposits are different, and I suspect there is a degree of corrosion going on in the mixed systems, as you say.

    Pex seems to be replacing plenty of copper these days, which is probably just as well, considering the cost of metals.
  20. maple1

    maple1 Minister of Fire

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    Disagree on iron + copper = corrosion.

    In a sealed/pressure system, at least.
  21. Eric Johnson

    Eric Johnson Mod Emeritus

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    Here's how I've got it plumbed up (and pressure tested). I'm going through the floor with black iron for stability (small rad on an uneven floor), but will put isolation valves and drain down below and either connect it to pex or copper.

    [​IMG]
  22. flameretardant

    flameretardant Member

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    Got anything to back that up? Did a salvage on a copper/iron system. The steel panels failed en masse in 3 years. All iron parts showed extensive grooving that worsened as it approached copper. Closed system. Water tests were fine. No excessive make-up was reported. Also, chemistry: Copper + iron/steel + water = galvanic cell = transfer of electrons = corrosion.
  23. maple1

    maple1 Minister of Fire

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    Just doing maintenance on my own boiler. I've had to disassemble some copper/iron connections, everything looked A-OK inside after 15 years or so. Copper + galvanized fittings I would say to be a different story.
  24. woodsmaster

    woodsmaster Minister of Fire

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    I don't have any data but I was told that my steel panel rads shouldn't be plumbed with copper so I used pex.
  25. coaly

    coaly Fisher Moderator Staff Member

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    The part you have is on the left. The elbow that mates to it is on the right. Pictured above is the tool that goes inside the union to remove the nipple from radiator. You will notice two raised nubs inside the fitting that the tool comes up against to turn it out. They went by thread size, not the union straight thread. (non tapered) Before anything was standardized, the threads could be different from mfg. to mfg. I run into Imperial threads on steam stuff too. Mostly Canadian locomotives.
    These are new old stock. I bought up a garage full of plumbing parts from a retired plumber that did a lot of steam work.
    When using a new piece that wasn't an original mate, you put a dab of valve grinding compound on the ball joint (the mechanical joint) and work it back and forth to lap them together for a steam tight joint. When you find one of us steam collectors with traction engines, road rollers and what-not, you'll find we aquire house parts in buckets of stuff we hang onto just in case. I have many like this with an adjustible shutter valve inside too.

    The bushings used on radiators in old homes had fancy markings like twisted ropes, dots, hash marks.......... so back in the day, the entire building matched ! It was an art back then that has been lost.

    I collect these bushings when I find them, and have a bucket full of all different designs. Just one of each, but quite a collection. I've always said "look long enough, you'll find someone that collects anything".
    antique NOS Rad EL.JPG

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