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Replace radiator with baseboard.

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Mike T., Swampeast MO
Mike T., Swampeast MO Member Posts: 6,928
in THE MAIN WALL
The more I think about the idea the worse it becomes...

The Baseray has about the same amount of head loss as ¾" pipe. Unlike a standing iron radiator it does not have natural convection of water inside the radiator itself to enhance its own flow.

So...the Baseray essentially acts like a horizontal pipe--true horizontal by the way and the dead men NEVER kept their pipes truly horizontal--the supplies ALWAYS pitched up slightly and the returns down slightly. I believe that 1" in 10' was common for "horizontals". So to have any chance you'd need to pitch the baseboard up about 1¼" higher at the return end. Even then, the dead men most likely wouldn't have used 12' of horizontal ¾" pipe (the rough equivalence of the baseboard). While ¾" moving 500#/hr is within the acceptable velocity range (about ideal), they would have bumped up to 1" to compensate for the nearly horizontal nature of the pipe.

If the math looks conceivably possible, you might try but I honestly believe you have little chance of success.

Comments

  • Mike C_4
    Mike C_4 Member Posts: 2
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    Replace radiator with baseboard.

    Need more advice please. If I replace a 1st floor radiator on a gravity hot water system with a 12 foot piece of Burnham 9A cast iron bsbd will it work if I increase the supply and return piping from the mains from 3/4" to 1" piping?
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
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    This system is STILL under gravity flow, correct?

    If so,

    Ready for some math?

    The 12' of 9A Baseray has 0.26" or 260 milinches of head loss. The old radiator effectively had zero as standing rads themselves were not used in the head loss calculations.

    Presuming you're using the 500#/hr rating AND that the existing radiator currently has about this amount of flow (maybe yes, maybe no) then to have any chance of success you need to remove at least 260 milinches of head loss from the piping.

    The only opportunity you have to remove head loss is via the branch piping. If the current branch piping is ¾" it has 25 milinches of head loss per foot of pipe. Equivalent length of 90° els is 25 x pipe diameter; 45° els count for 17½ x pipe diameter. Using those numbers calculate the head loss in the branch piping (both supply and return) UP TO the hand valve/rad el.

    Remember that you must remove AT LEAST 260 milinches of head loss from the piping to get at least the current amount of flow. If the existing branch piping has less than 260 milinches of head loss already, hang it up. 260 milinches = 10.4' of ¾" pipe or equivalent. You'll get less flow through the baseboard and possibly none.

    If the existing branch piping has at least 400 or so milinches of head loss then you might be able to do it... 400 milinches = 16' or ¾" pipe or equivalent.

    1" pipe at 500#/hr of flow has 10 milinches of head loss per foot. Equivalent length for fittings follows the same formula. If you can remove AT LEAST 260 milinches of head loss from the NEW piping, try it. A rather doubt this will be possible as your new piping for the baseboard is almost certain to be significantly longer. While you can move the supply/return takeoffs from the mains (with LOTS of work I might add), DO NOT move them past another connection. In other words there cannot be any other takeoffs from either the supply and return mains in between the takeoffs for a given radiator.

    Check the numbers and write back. If the current branch connections are short (likely), you don't even have to bother calculating...

    Here's some numbers to help with calculating equivalent length. For standard iron pipe:

    ¾" = .824" inside diameter

    1" = 1.049" inside diameter.

    Another BIG problem is that you'll most likely have a significant amount of horizontal piping to serve the baseboard. If over 10' or so of horizontal the dead men usually increased the pipe one additional size to compensate.
  • LaurenL
    LaurenL Member Posts: 3
    edited January 2012
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    Converting cast iron stand up radiators to Burnham 9A (Steam system)

    Hi,

    I have a steam cast iron stand up radiator in a bedroom and our plumber/contractor is separating the bedroom to add a bathroom. Now, the existing radiator will be too much for that soon to be smaller room and i need a new heating system for the new bath. someone suggested i get rid of the old bigger stand up radiator and get 2 new Burnham 9A baseboard radiators. I was told it is a one pipe system and the pipe coming in is 1" and 1/4 but the radiator is 3/4. My plumber said he can make this work but i just read somewhere online that this is not a good idea.

    Any advice?? Will this cause too much heat loss?



    And i am just a homeowner so can you answer me like the "for dummies" books!

    Thank you!!
  • kcopp
    kcopp Member Posts: 4,436
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    Not advised...

    you are going to never be happy w/ the baseboard on the steam. Get a smaller radiator or smaller vent to reduce the heat. You will get nothing but problems... water hammer & poor heat. You would be better off capping the line off and going w/ electric heat!
  • Steamhead
    Steamhead Member Posts: 16,881
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    Depending on the size of the bathroom

    a short length of Baseray might work. I've seen up to 6 feet work with a single 3/4" valve connection on one-pipe steam, though anything over 3 feet is pushing it.



    I would NEVER suggest putting an electric heater in a bathroom. Mixing water and electricity is a very bad idea.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • kcopp
    kcopp Member Posts: 4,436
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    electric mat radiant?

    see that a lot under tile.
  • Paul48
    Paul48 Member Posts: 4,469
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    Trust Me

    Keep  the radiator and add a thermostat radiator valve. You won't be happy with the output of baseboard.
  • LaurenL
    LaurenL Member Posts: 3
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    It is only 2ft long

    Thank you for the comments so far. The Burnham 9A we would be using is only 2ft long and will only be heating a bathroom thats roughly 7ft by 6ft. Does that change your opinion?

    We are having a hard time finding used steam radiators that we can get and from a source we trust.



    thoughts?
  • LaurenL
    LaurenL Member Posts: 3
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    Thermostat Radiator Valve

    I just saw your response about a radiator valve; I had no idea that was an option!  Is that the same thing as a "Thermostatic Radiator Valve" (googled, and the wiki for TRV's came up)? 

    Do TRV's work for steam systems, and if so, any advice on where to buy and how much they cost?  Is there any downside to using them? 

    Thanks!
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