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  1. #1

    Default Indirect Water heater - use with baseboard & HVAC heat

    I have an oil boiler runs around 85% efficiency. Right now it has a direct coil in it.
    I've been thinking of getting an indirect water tank to increase the efficiency of the house hot water, plus I've got 3 kids it makes sense.
    So looking around I was thinking I get through the whole summer/spring using less then 1 tank of oil. During the winter I end up getting 1 or 2 tanks, depending on how cold. Mainly because we have baseboard heating in the basement (which my wife leaves on set to 68 during the cold winter days since it heats up the 1st floor, (and with the kids on the floor it makes sense) The HVAC keeps the rooms themselves warm enough, but the basement heat really helps. In any case I was thinking it'd be nice, if the baseboard heat could be heated when needed via a 2nd coil in an indirect water tank?

    Basically as follows:
    Bottom coil of tank is heated via the boiler.
    Top coil when there's call for it would run a pump that would run water between the indirect tank and the baseboards.
    There would need to be something to add more water to that circuit when needed.

    Any thoughts?

  2. #2
    Join Date
    Jul 2009
    Posts
    159

    Default Re: Indirect Water heater - use with baseboard & HVAC heat

    JWK117,

    Have you consulted with a heating contractor on this???

    You submitted this topic back in January of 2012, and numerous members submitted extensive, informative input on the suggested way to resolve this issue; why are you posting back now with exactly the same question???



    https://advice.thisoldhouse.com/show...854#post257854
    Last edited by Pelton; 08-06-2013 at 05:04 PM.

  3. #3

    Default Re: Indirect Water heater - use with baseboard & HVAC heat

    I have gotten a quote for an indirect tank with a single coil, for the normal hotwater use in the house. But my question is whether It would make sense and/or if it would work. To have a second coil in the indirect tank that would be used to run the baseboard and possibly the hot water to the HVAC? I've seen 2 and 3 coil tanks, which are primarily branded for have secondary heat sources, ie solar and geothermal to heat the water.

    I would think that if the bottom coil from the oil boiler heated the water to around 120, Having a second coil that would be thus heated up from the water in the indirect tank. Could then be run to the baseboard and could heat that, granted it would probably not be as responsive as running through the boiler directly.
    I know that usually the baseboard runs around 180 degree water, but running at a lower temperature for a longer time, via a pump. Would probably cost less then burning the oil.

    The vendor I got a quote from said he didn't know how/if it would work, and or how efficient it would be. I'm more curious to see if it's possible and/or if anyone has done it.

    The vendor I spoke with basically would set it up so the baseboard and HVAC would still go directly through the boiler not through the indirect tank.

  4. #4
    Join Date
    Aug 2008
    Posts
    83

    Default Re: Indirect Water heater - use with baseboard & HVAC heat

    I agree with the others that you should consult the Yellow Pages under "Heating Contractors" and get at least one or two other contractors over the house to give you an estimate of for how much, & what & how an indirect can be installed.

    There are plumbing codes that would prevent an installer from putting in some of the piping arrangements you list in your post---remember the indirect wh stores POTABLE (drinkable) hw for domestic consumption & use, and MUST NEVER be mixed with the boiler water, which is dirty & will make you sick if ingested, and slime up your skin if you take a shower.

    The most economical way of saving oil & getting adequate heat for baseboards and the indirect hwh, and which I agree with, was well noted & specified by Dobbs over a year ago---you're burning much more oil now by not replacing your current aquastat & having a "cold start" aquastat installed; your present aquastat must CONSTANTLY turn on & off 24/7 in order to keep an inadequade paltry gallon of water hot, which is insufficient for domestic hw needs----the new aquastat will burn much less oil.

    In regards to accepted piping schemes, standard practice is to pipe any baseboard loops by using zone valves (less frequently zone circulators) directly off the boiler, using the same pump on there now, & installing a t-stat in the zoned room containing the baseboard loop (known as a zone loop); consult the Caleffi piping circuits & site to study variations on various hydronic (hot water) piping loops, especially Fig. 3-5, 3-6, 3-7, 3-8, 3-16, 4-7 (TRV/thermostatic radiator valves), & 5-1.


    http://www.caleffi.us/en_US/caleffi/...onics_5_US.pdf
    Last edited by dodsworth; 08-09-2013 at 04:12 PM.

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