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  1. #1
    Join Date
    Nov 2014

    Default Cast iron radiators

    Last year I had 2 cast iron radiators crack from a freeze up in the crawl space just under the part of the house where these radiators are located. It is not a large area about 100sq feet in total and not an area where a lot of time is spent. My plumber bypassed these two radiators and the rest of the house was fine through the rest of the season. Is it possible to put in some kind of baseboard heat like a slant fin in this area of the house without adding a second zone and without replacing all the other cast iron radiators? Would I be better off just putting in some electric baseboard to supplement and take the chill out of this small area when needed?

  2. #2
    Join Date
    Sep 2012

    Default Re: Cast iron radiators

    you can add some slant fin if you have a forced hot water system. you can not do it if you have a gravity fed system or a steam system. for such a small space, electric might be your cheapest option.

  3. #3
    Join Date
    Feb 2008

    Default Re: Cast iron radiators

    I agree.

    The question is---why did the rads freeze & crack---some common causes are there is a "draft" in the crawl space due to an opening in the foundation or foundation framing that is letting cold air in---a few hours spent installing pink fiberglass batts all around the crawl space often works wonders in preventing this from happening again---always use a dust mask when working with insulation to prevent lung damage in future years.

    If you use either hot water baseboard or cast iron rads you'll have to include an additive to the boiler system water called propylene glycol in order to avoid another freezeup & loss of the baseboard (or rads, if you use rads).

    Someone (yourself or your heating tech) would have to reconnect the boiler piping to the new Slant/Fin (or small rads if you use rads) & add about a gallon of the propylene glycol to the boiler system water as probably the least expensive way to make this fix; hw heat is usually much less expensive than electric baseboard.

    Propylene glycol is a non-toxic antifreeze liquid sold at the home improvement stores; if you know how to solder copper tubing (unless you have PEX plastic) you might be able to do it as a diy project.

    Sometimes you can pick up 2 used small rads at a junk yard, since many people these days turn them in for the cost of the metal & can be less expensive than new baseboard; make sure there's no cracks & do an air pressure test before buying.

    Since this is an out-of-sight crawlspace soldering together a few 10' sections of type "M" 3/4" (thin walled) copper tubing would probably suffice over the cost of radiators or two 4' sections of baseboard; at least one bleed valve would have to be included near the top in any of the mentioned setups to bleed the air out.

    Use the search box at the top of the site at "supply house" to view an item & get a ballpark figure as to the cost of the components mentioned---for example, enter "Slant/fin baseboard" in the search box to get the price quote for all S/F baseboard; some states don't charge taxes on mail order items, some do----but also check local prices at the home improvement stores for the best deal; many local heating supply shops will now sell items to the DIYr at wholesale, so check those as well.

    Figure 100 sq.ft. of crawl space X 35 btu/sq.ft for amount of heat needed for the crawl space= 3500 btu/hr; baseboard heat output= approx 530 btu/hr per ft. divided into 3500= approx 7 to 8 feet of baseboard, or 2 sections of 4' baseboard.

    Even a small rad will put out a lot more btu/hr than baseboard & the cast iron composition extends the heat output greatly.

    There's even an 8' section of Burnham cast iron radiant baseboard that you might find 2nd hand at a junk yard that puts out 580 btu/ft., which would be ideal for a rugged environment & involve less assembly time.
    Last edited by NashuaTech; 12-01-2014 at 12:49 PM.

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