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Adding cast iron radiators to hot water system?

anthonya89
anthonya89 Member Posts: 5
in THE MAIN WALL

Tried to find info on this, but couldn't find too much. I've got a oil fired hot water system (circa 1980s copper pipes with new within the last 10 years boiler) with a mix of baseboard heaters and these awful loud radiant blower heaters (they have fins like baseboard, but an electric fan that blows across them). I was wondering if its possible to take out the blower units and plumb in cast iron radiators instead? I think they'd throw off way more heat, but they'd be on the same loop as some of the baseboard and I'm not sure if that'd cause an issue for some reason? I've installed rads on a steam system, but not hot water (yet). Any advice or issues I should look out for or any help would be appreciated!

For reference, I'm in NH so it does get cold, but I also have a woodstove as back up, but also looking to rely less on that.

Comments

  • DCContrarian
    DCContrarian Member Posts: 677

    The blowers are called "convectors."

    They're usually used where space is tight, because they can put out a lot more heat in a small space than other options. Just to put things in perspective, a toekick heater that is 19-1/2 inches wide and 4 inches high is rated for up to 12,000 BTU/hr. Cast iron baseboard is rated at 550 BTU/hr per foot, so that's equivalent to 22 feet of baseboard.

    EdTheHeaterMananthonya89
  • hot_rod
    hot_rod Member Posts: 23,349

    perform a room by room heat load to see what your options are

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    EdTheHeaterManDCContrarian
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 9,360
    edited July 28

    This book is like a crash course on all things for hydronic heating. Gives you the basics in an easy to understand format. https://s3.amazonaws.com/s3.supplyhouse.com/product_files/108119-Reference%20Guide.pdf You can find easy to do heat loss calculations online. Here is one that will do one room at a time. https://www.omnicalculator.com/construction/heat-loss

    Finally, putting different type heat emitters on a single zone never works out. Baseboard should not be on the same thermostat zone as convectors, Standing cast iron radiators should never be places on the same thermostat zone as fin tube elements like copper/aluminum baseboards radiators, etc…

    Try to batch each different type of heat emitter on one zone operated by one thermostat, then batch cast iron on a separate zone operated by a different thermostat.

    Edward Young Retired

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

  • DCContrarian
    DCContrarian Member Posts: 677
    https://forum.heatinghelp.com/discussion/comment/1806916#Comment_1806916

    Right. Start at step one.

    It would also help to take the cover off the convectors and see the make and model, get an idea of what's in there now.

  • anthonya89
    anthonya89 Member Posts: 5

    Thank you for the advice and links. Yea it's funny the convectors are on the same loop as the baseboard and a toe kick in the kitchen. It's a big open room too with lots of windows. I'll try to do a heat loss calculation and see what that says. I'll also double check the convectors to see what their output is.

  • anthonya89
    anthonya89 Member Posts: 5

    Also because im curious, whats the reason why different types of heat emmiters shouldn't be on the same zone? I assume there's a good one and I just don't know it lol

  • DCContrarian
    DCContrarian Member Posts: 677
    https://forum.heatinghelp.com/discussion/comment/1807195#Comment_1807195

    All of the emitters in one zone are controlled by one thermostat. Different types of emitters respond to the thermostat at different speeds. So a convector will be at maximum output within about a minute of the thermostat turning one, while a cast iron radiator might take 20 minutes to get up to operating temperature. One thermostat is going to have trouble keeping rooms with both kinds comfortable.

    anthonya89
  • anthonya89
    anthonya89 Member Posts: 5

    That makes sense.

    So what I've got is a large Living room/kitchen that's open concept, with lots of big picture windows. Using that linked calculator I came up with a heat load of just under 30k btus, though it may be more with the big windows.

    Right now I've got 2 upright 3 beacon morris k84 twin flow iii convectors, one 6ft stretch of copper fin baseboard and one 12ft stretch of the same baseboard.

    I think they put the convectors in because there's not much wallspace for more baseboard, but as I said they are loud and what we've got now isn't putting out enough heat anyway. Guess I'm trying to figure out the best way to add more heat the easiest, so any suggestions are welcome.

  • DCContrarian
    DCContrarian Member Posts: 677

    I need help parsing this sentence: "Right now I've got 2 upright 3 beacon morris k84 twin flow iii convectors."

    The Beacon Morris K81 Twin Flow III is a kind of convector. Do you have three of them? What does "2 upright" mean in that sentence.

    The K81 is rated about 10K BTU/hr, 18 feet of baseboard would be another 9K, so that's 39K total if there's three of them. What's your boiler rated for?

  • anthonya89
    anthonya89 Member Posts: 5
    https://forum.heatinghelp.com/discussion/comment/1807246#Comment_1807246

    Sorry for the confusion, I have two of those convectors they are upright convectors with a metal cover. I have one other that is a kickspace Hester in the kitchen. I couldn't access it to find a sticker or data plate so I assumed it was the same type of heater, but I might be wrong. Thank you for your patience as I'm trying to learn about it all as I go.

    I will have to double check the boiler rating and get back to you on that.

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