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sizing and adding additional radiators

cmeyers011
cmeyers011 Member Posts: 2
so. What is needed to size a boiler? and how will that information help me in the decision to add 2 radiators in the basement. (probably on the ceiling above the main).?

Comments

  • delta T
    delta T Member Posts: 844
    Assuming this is steam (not my personal area of expertise, others on here know much more than I do) you need to know the EDR (equivalent direct radiation) of all attached radiation, add a 'pickup factor depending on your piping, and you have it. Search the wall, there are numerous threads about how to do this. If you are planning on adding the radiators at a later date, make sure that sizing the boiler for all the radiation (future rads included) will not cause the current radiation to be undersized in relation to the boiler. This will cause short cycling and all the associated problems that go with it (loss of efficiency, higher wear and tear on the boiler and associated controls etc.) At the same time, if you size to only the existing radiation and then add radiators, the boiler may not be able to satisfy the demand, causing a host of other problems not least of which being cold radiators. All depends on how big those two rads will be and how much fudge you have in the ratio of boiler to rads.

    Hot water is different. Let us know which and give us some more details about your system and we can probably help you out.
  • If this is steam, you could always add a hot-water loop to the existing system, controlled by its own thermostat.
    This would be especially useful for basement radiation, where the height of the ceiling position could be lower than needed for the "a" dimension.--NBC
  • ChrisJ
    ChrisJ Member Posts: 11,565
    edited September 2015
    On a steam system my current opinion is for most anything between a 15-33% pickup factor is fine but I'd never go above 33%. If going below 33% make sure your piping is all proper and insulated well.

    So, if you can find a boiler that falls into that range on your system including the extra radiators that's perfect. If you're not sure about adding the extra radiation, but may, stay closer to the 33% side of it.

    33% meaning take your total radiation in EDR, multiply it x 240 and then multiply that times 1.33. This is the maximum DOE output you want on a boiler.

    For example, for 300 sqft of radiation you'd want a DOE output of no more than 95,760 btu/h which is 33% more than the radiation can condense.


    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • SWEI
    SWEI Member Posts: 7,356
    Don't forget that the square foot ratings on boilers already include both pick-up and piping factors.
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 11,565
    SWEI said:

    Don't forget that the square foot ratings on boilers already include both pick-up and piping factors.

    And that many if not most steam radiation is already oversized so there's no need for a pickup factor, only piping.

    Sorry, I can't help it. :(
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • JUGHNE
    JUGHNE Member Posts: 8,315
    PGG (pretty good guess) and close to WAG:

    First, you have existing boiler? and want to add radiation to the basement?
    The basement is already getting some heat from boiler and piping.
    If you just finished/insulated part of it, less heat is needed for that area.
    Most boilers, even steam, are somewhat oversized and the additional heat needed for the basement may be a small fraction of the capacity of existing boiler.

    The hot water loop NBC mentioned may be the simplest installation and give you T-stat/zoning for that area.
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