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Installing cast iron radiatiors. Pipe direct or reverse return?

SuperTech
SuperTech Member Posts: 1,857
I haven't been here in a while since my mind has been on A/C the last few months but heating season is back in full swing and I'm thinking about modifying my boiler again.

I came across some really nice 75-100 year old radiators for free. I've been planning on using cast iron radiatiors for a finished room in my basement.
One problem is that the radiators were originally used in a single pipe steam system. Has anyone ever converted old rads before? How much struggling is involved in the process?
The rest of my house was piped in with a two pipe Venturi tee reverse return setup for cast iron baseboards. I'm planning on installing zone valves and making this room a zone with two good size radiators. Should I bother piping them reverse return or would it be better to pipe them direct?

Any thoughts or opinions would be great to hear!

Comments

  • JUGHNE
    JUGHNE Member Posts: 10,334
    Are the CI rads connected across the top?
  • hot_rod
    hot_rod Member Posts: 18,281
    Got a pic? Are the sections connected across the top? I have used rads with just a single tapping, as long as the sections are connected.

    These valves are available for one hole rads. A TRV can be added.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • SuperTech
    SuperTech Member Posts: 1,857
    They aren't connected at the top. I'll take pictures after work today. They have what appears to be plugs at the top that look like they can be used for hydronic applications. I bet they will be tough to get out!
    At the bottom they were taken apart at union that was connected to a valve. I don't have the other half of the union either, the connection at the bottom of the radiators are going to have to completely redone.

    I'm tempted to get a few more from the guy I got them from. If only they weren't so damn heavy!
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 13,175
    I wouldn't bother with reverse return for only two radiators.
    SuperTech
  • SuperTech
    SuperTech Member Posts: 1,857
    edited October 2018
    > @EBEBRATT-Ed said:
    > I wouldn't bother with reverse return for only two radiators.

    That's what I was thinking. I know it's usually best to use reverse return, but I wasn't sure if I'd see any benefit from it.

    Any recommendations for working on the radiators? I'm not sure if penetrating oil will help me get the plugs and old fittings out of rads. I'm guessing that applying heat and using leverage is my best bet.

    I just don't want to damage the radiators and end up with five hundred pounds of scrap metal.
  • hot_rod
    hot_rod Member Posts: 18,281
    warm the metal around the plug, sometimes an impact wrench will hammer them out

    Drill and saw blade is the last ditch method
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    SuperTech
  • SuperTech
    SuperTech Member Posts: 1,857
    I've made some progress. After breaking two breaker bars try to spin the plugs out of the radiators I decided to cut the hex nut off with an angle grinder.

    Afterwards I was able to bore out a hole large enough for a 3/4" nipple. I plan on tapping the hole and welding the nipple in if necessary.

    I'll attach some pictures of the indirect I'm installing as well.
  • JUGHNE
    JUGHNE Member Posts: 10,334
    It is looking good for your rad work.

    However, FWIW, I did an indirect exactly like that and the die-electric union leaked within one year.
    Today I would use a SS union. The only disadvantage I have encountered is that they have to tight as hell, no brass insert to compress.

    You can mention dielectric unions to 10 pipefitters and get 12 opinions.
    SuperTech
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 13,175
    @jughne
    I agree. Never had much luck with die-electric anything. They always leaked for me
  • hot_rod
    hot_rod Member Posts: 18,281
    SuperTech said:

    I've made some progress. After breaking two breaker bars try to spin the plugs out of the radiators I decided to cut the hex nut off with an angle grinder.



    Afterwards I was able to bore out a hole large enough for a 3/4" nipple. I plan on tapping the hole and welding the nipple in if necessary.



    I'll attach some pictures of the indirect I'm installing as well.

    Get the oil cleaned off with some contact cleaner or alcohol and Loctite the nipples in.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • SuperTech
    SuperTech Member Posts: 1,857
    > @EBEBRATT-Ed said:
    > @jughne
    > I agree. Never had much luck with die-electric anything. They always leaked for me

    I was thinking that the die-electric unions were a must have to protect the tank. I've used them on the electric water heater I have next to the indirect, luckily I haven't had any leaks.
    Most of the time at work the boss doesn't want to spend the extra money on die-electric unions so my experience with them is somewhat limited. I don't think I have ever seen a stainless steel union.
  • SuperTech
    SuperTech Member Posts: 1,857
    edited October 2018
    @hot rod Said:> Get the oil cleaned off with some contact cleaner or alcohol and Loctite the nipples in.


    I might try that before breaking out the welder. My only concern is that if you look at this picture you can see how thin the metal is where I will tap. Even if it doesn't leak with Loctite I might need to re-enforce the connection with the welder.
  • hot_rod
    hot_rod Member Posts: 18,281
    welding cost iron can be tricky, usually a wider will preheat the iron with a torch, the weld.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • steamedchicago
    steamedchicago Member Posts: 72
    SuperTech said:

    > @EBEBRATT-Ed said:

    > @jughne

    > I agree. Never had much luck with die-electric anything. They always leaked for me



    I was thinking that the die-electric unions were a must have to protect the tank. I've used them on the electric water heater I have next to the indirect, luckily I haven't had any leaks.

    Most of the time at work the boss doesn't want to spend the extra money on die-electric unions so my experience with them is somewhat limited. I don't think I have ever seen a stainless steel union.

    You shouldn't need dielectric couplings in a heating system. The water is pretty well de-oxygenated, so little corrosion occurs. In open systems (like potable water systems), they're necessary.

    I've been told one of the common reasons for their failure is they get over tightened, and the gaskets are distorted, so there is metal-to-metal contact that defeats the point of the dielectric.
  • SuperTech
    SuperTech Member Posts: 1,857
    > @steamedchicago said:
    > > @EBEBRATT-Ed said:
    >
    > > @jughne
    >
    > > I agree. Never had much luck with die-electric anything. They always leaked for me
    >
    >
    >
    > I was thinking that the die-electric unions were a must have to protect the tank. I've used them on the electric water heater I have next to the indirect, luckily I haven't had any leaks.
    >
    > Most of the time at work the boss doesn't want to spend the extra money on die-electric unions so my experience with them is somewhat limited. I don't think I have ever seen a stainless steel union.
    >
    > You shouldn't need dielectric couplings in a heating system. The water is pretty well de-oxygenated, so little corrosion occurs. In open systems (like potable water systems), they're necessary.
    >
    > I've been told one of the common reasons for their failure is they get over tightened, and the gaskets are distorted, so there is metal-to-metal contact that defeats the point of the dielectric.

    The dielectric unions are only on the cold inlet and hot water outlet of the tank, the unions on the boiler side of the indirect are just regular unions.