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  1. #1

    Properly sizing indirect water tank

    I'm thinking about replacing my existing gas-fired water tanks (30 gal & 40 gal) with aa single indirect tank on a priority zone off of my burnham series 2 boiler (164k btu input). I'm in the process of converting to central air / forced air heat, so heating the indirect tank would really be the only thing the boiler is doing, no other heating zones. (though I'm planning on putting a couple of smaller radiant floor zones in, mostly just to warm up tile in a bathroom.)

    The question is, with this size boiler, and not worrying about any hydronic heating zones, how large a tank can I put in before I run into problems with the boiler not being able to heat the tank quickly / efficiently? I'd love to put in an 80 gal tank, but I'm concerned the boiler just doesn't put out enough btu's to heat it effectively.

    Thanks in advance for any help!

  2. #2
    Join Date
    Mar 2005
    Location
    burlington county n.j.
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    9,763
    with that tank being the only thing on the boiler you could probably put in a 30 gallon tank and never run out of hot water.

  3. #3

    Thanks!

    Quote Originally Posted by t527ed View Post
    with that tank being the only thing on the boiler you could probably put in a 30 gallon tank and never run out of hot water.
    One concern I have is that we're probably building a new master bath, which will have a jacuzzi & shower with multiple heads / body sprays / etc.

  4. #4
    Join Date
    Jan 2004
    Location
    PA
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    68,759
    That boiler will give you a recovery rate of roughly 175 gallons an hour at 90°F rise.
    And 157 at 100°F rise.

    Its more then enough for an 80 gallon indirect.
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  5. #5
    Join Date
    Jan 2004
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    PA
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    68,759
    That boiler will give you a recovery rate of roughly 175 gallons an hour at 90F rise.
    And 157 at 100F rise.

    Its more then enough for an 80 gallon indirect.
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  6. #6

    Thanks!

    Many thanks, beenthere, I appreciate the feedback. What's your thoughts on adding a tempering tank before the indirect to bring the water closer to basement room temperature? I was toying with the idea of re-using the 40 gal direct-fired gas tank for this purpose, just pulling the jacket & insulation off.

  7. #7
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,759
    If your exisiting water heater tank is in good shape. Use it.
    It will help. You won't save a big savings in any one month. But over the course of a year it adds up.

    You might want to have a pan installed under it though. They tend to sweat a lot.



    PS: Make sure you have a bypass installed, in case it starts to leak down the road.
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