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Does it matter which side a bleeder valve on hot water cast iron radiator is placed?

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eclecticmn
eclecticmn Member Posts: 121
I have 3 old cast iron hot water radiators. Never used by me. The rest of the house has several in use. All 3 have water flow through the top and bottom. If my water supply valve comes in the bottom on one side does the bleeder valve have to be on the opposite side?
In the used radiators I picked up all 3 have the bleeder valve on the same side as the supply valve. The opposite side lower 1 1/2 opening is difficult to take off and was painted shut. I am still trying to remove these plugs. I scored the paint and tried liquid wrench.

All of the existing ones in the house have bleeder valve on opposite side from valve. A few have the supply and return on some side.
Home owner near Minneapolis with cast iron radiators, one non working slant fin now ripped out, and hot water heat.

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  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,166
    edited January 2023
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    NO. The air vent location on a hot water radiator has only one function. to let the air out when you fill the system. Once the air is removed then the valve is closed for the entire time the system is operating.

    On a steam radiator the vent has a different job. It must be automatic and operate on every heating cycle to let the air out so the steam can get in. It must be on the opposite side of the steam inlet, Is works better near the bottom. Not so on a water radiator. The vent can be manual or automatic, it must be at the top, and it is a one and done situation.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    eclecticmn
  • Danny Scully
    Danny Scully Member Posts: 1,429
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    Ideally it would be on the return side of the radiator. 
    eclecticmn
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,166
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    Ideally it would be on the return side of the radiator. 

    On a Water rad... What is the difference? In my experience whether the circulator pump is operating or not, the water will get to the top on either side. The air will leave the radiator on either side. "...for a difference to be a difference it has to make a difference". Left air or right air is still air? isn't it?

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • hot_rod
    hot_rod Member Posts: 22,467
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    A vent like this is a nice option, both a manual and auto. Or remove it and a check valve shuts off the opening.

    Radiators are great air purger devices, at least yearly if not always have a vent that can release any air that traps up high.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream