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radiator water rise question

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Brian K
Brian K Member Posts: 7
in THE MAIN WALL
Hi everyone,

I've got a real quick question (sorry to bother you guys)... I'm building a "green" cabin and I'm trying to absorb some heat from my fireplace to heat some old water radiators (actually just one) upstairs. How do I calculate if there is enough heat absorbed in a pipe going into my fireplace (18gph at 80degree temperature rise) with a product called a "hot rod" to lift water in a pipe to the upstairs bedroom (up 12feet or so), through a water radiator, and then back down again to circulate in a gravity-based system. What size pipe should I use? I think I would need an expansion tank in the system, correct? Does it always have to be at the highest point?

If anyone could point me in the right direction... I'd certainly appreciate it.
I'm really stuck on this one.

Thanks,
Brian
brian04@NOSPAMaudionce.com

Comments

  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928


    Can you post a web link to the "hot rod" device?

    Watch out or you'll build a bomb!
  • Brian K
    Brian K Member Posts: 7
    Yukon \"Hot Rod\" Link

    Here's a link to that "hot rod" device:

    http://www.yukon-eagle.com/hotrod.htm

    It's intention is for hot water pre-heating, but if I had several in a fireplace I wanted to use one per hot water radiator located about 15 feet above the fireplace.

    How would I also calculate the BTUs of this rod?

    Thanks guys...
    Brian
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
    Scary

    "All system components must be rated for at least 150 psi @ 210°F???

    That's the rating of the supplied relief valve.

    Do you have any idea what would happen if a cast iron rad gave way under those conditions?

    BTU/hr calculation is simple. 8.33 (pounds per gallon of water) * 18 gallons per hour * 80° temperature rise = 11,995.2 btu/hr. That's quite a lot of output potential.

    What happens when you don't need anywhere near that amount of heat and the fire is still burning? Frequently blow off extremely hot, HIGHLY pressurized water?

    SCARY STUFF!!!!

    I hope you don't have a family. If you do, you might not have them for too long...
  • Brian K
    Brian K Member Posts: 7
    being safe...


    I agree, I want to keep this safe, but that's a good thing that I can collect that much heat. I'd like to consider how to do this right... putting in an expansion tank, for instance, or enabling the hot water to route to an outside "hot spring." Any ideas? I take it that getting the hot water to rise to an upstairs radiator will not be a problem in a gravity fed configuration with an expansion take in the attic.

    Other ideas?

    Thanks,
    Brian
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928


    Arms flailing wildly. "Danger Will Robinson. Danger."

    I'm afraid to even speculate about how to safely use such a device to heat standing iron radiators via gravity flow. 150 psi @ 210F is WAY beyond ANYTHING I've ever read about considered safe for such. Sounds similar to the very old British systems that suffered "spectacular" failures.

    You have to expect "dumps". Then you have to make certain that the radiators stay filled after such dumps. Let the water level in the radiator drop and the output ability of the radiator will drop nearly as fast as much of the iron won't be in contact with the water. That only adds to the potential for overheating.

    "Gangs" of those devices would be even worse. You couldn't even consider series connection and parallel connections are very difficult to engineer for consistent flow through each element.
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