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  1. #1
    Join Date
    Apr 2013
    Location
    Massachusetts
    Posts
    28

    Default Radiator - can I used for FHW?

    My house currently has steam radiators pictured below. Can these be converted to work with a forced hot water system? How can you tell?






  2. #2
    Join Date
    Nov 2012
    Location
    central pa
    Posts
    98

    Default Re: Radiator - can I used for FHW?

    yes but you will need to have 2 lines on in and one out. And those old fittings can be next to impossible to get out I have converted some and have had to drill and tap the holes because I couldn't get the fittings out. also make sure you flush out all the rust or you will clog your circulators.

  3. #3
    Join Date
    Feb 2008
    Posts
    200

    Default Re: Radiator - can I used for FHW?

    Rekonn:


    The steam rads you show in the photos look like they're in very good shape, but there are a number of problems involved if you want to convert them from steam to forced hot water.

    I would recommend you have a pro come over the house that has done this before (consult the Yellow Pages under "Heating Contractors", or call your regular boiler man); as I noted in a previous post, cast iron rads have a lot of MASS---meaning that the hot water can easily transfer all of its heating BTUs into the metal structure of the cast iron to provide heat for the house for a very long time between boiler heating cycles.

    Some of the problems with a conversion is that:

    1) steam rads operate at 1 to 2 psi pressure, but FHW rads operate at 15 to 30 psi, so the likelihood of leaks if you try to use them as FHW rads is a real possibility, especially if the rads are internally corroded after years of use in a steam system.

    2) The steam rads often have a single opening on one side at the bottom, but FHW rads need a SUPPLY opening on one side, and a RETURN opening on the other side; thus a DRILL & TAP hole often has to be put in the other bottom side---the rad in your photo seems to have a removable cap on the other side.

    3) the STEAM VENT (being in the middle of the steam rad) is in the wrong position for FHW, which requires a vent at the TOP of the rad, otherwise air will collect at the top half of each of the rads, making them lose a lot of heating efficiency; thus, the current steam vent has to be plugged & a new vent hole must be DRILL & TAPPED at the top of each rad.

    4) the rads as they are now have to be PRESSURE TESTED by the heating contractor using at least 40 psi air pressure, with a pressure dialed air compressor, for a length of time such as 15 minutes, to see if any leaks show up; even if they pass the air pressure test, there's no guarantee that they won't start to leak some time down the line when you have them in operation during the heating season.

    5) cast iron rads are more difficult to calculate as to heat output/heat loss calculations (see below) to determine how many you have to put in each room to obtain adequate heat; they are best placed a) DIRECTLY UNDER A WINDOW in each of the rooms so they will offset the cold blast from the window glass, and b) so they will create a convective air current to circulate the hot air around the room.

    On the other hand, cast iron rads are excellent convectors of heat, and are far superior to baseboard in this regard; they put out a lot of heat, and stay warm a long time on a cold winter day; so they provide better comfort, are more efficient than baseboard, and may even save $$$ on fuel expenses.

    On the other hand, the market for scrap metal has gone thru the roof, & junk yards are paying lots of money these days for cast iron rads--------consult the Yellow Pages under "Scrap Metal" & call to see how much $$$ you can get for the rads--see if the scrap metal co. can pick up the rads---you're asking for a hernia if you try to move them yourself!


    http://www.colonialsupply.com/resources/radiator.htm
    http://www.antiqueplumbingandradiators.com
    Last edited by Dobbs; 05-29-2013 at 04:52 PM.

  4. #4
    Join Date
    Apr 2013
    Location
    Massachusetts
    Posts
    28

    Default Re: Radiator - can I used for FHW?

    Thanks a ton for all that info! Ok, radiator conversion sounds like quite the labor intensive process. And that's with everything going as planned. The risk of developing leaks seems high and will add even more time/expense.

    How do you think the cost of conversion would compare with buying new radiators meant for hot water? Such as Burnham Slenderized radiators, or Runtal wall panels?

  5. #5
    Join Date
    Feb 2010
    Location
    South*East
    Posts
    1,217

    Default Re: Radiator - can I used for FHW?

    Quote Originally Posted by Rekonn View Post
    Thanks a ton for all that info! Ok, radiator conversion sounds like quite the labor intensive process. And that's with everything going as planned. The risk of developing leaks seems high and will add even more time/expense.

    How do you think the cost of conversion would compare with buying new radiators meant for hot water? Such as Burnham Slenderized radiators, or Runtal wall panels?
    The cost for cast iron radiators is through the roof. The cheapest way would be to use copper fin baseboard. If it was mine I would try to convert the radiators. There will be no need to drill and tap holes for the vents. If you look at the end of the radiator near the top you will see a 1/8" plug. I don't think you will have any problems with them leaking as long as you don't miss handle them. They are the type that is assembled using steel push nipples. The rods that pass through the radiator hold the sections together. The plug as well as the fitting on the opposite side can be removed by laying the radiator flat on the floor and using a 2' pipe wrench.
    John

  6. #6
    Join Date
    Jul 2009
    Posts
    163

    Default Re: Radiator - can I used for FHW?

    I tend to agree with John; the rads look to be in good enough shape with the required removable plugs positioned in the right places, to make the conversion (I would recommend a pro do it); the benefits of cast iron rads' ability to produce outstanding "fat" convective and radiant heat, as opposed to the relatively "thin" heat you'll get with copper-finned baseboard has to be experienced to be enjoyed.

    If a leak problem does arise with one or two of the rads somewhere down the line, they can easily be changed out with a new cast iron rad, or the units you mentioned, such as the newer stainless steel rads that are so popular in Europe http://www.Runtal.com & now catching on here.http://www.hydronicalternatives.com

    You'll save lots of $$$ if you can use most or all of the rads you have now.
    Last edited by Pelton; 05-30-2013 at 10:19 AM.

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