3 ton vs 4 ton delima

Discussion in 'Quotes and Proposals' started by gbuck, Feb 6, 2011.

  1. gbuck

    gbuck New Member

    i just caught something on the load calc, he based my heatload with a propape hot water tank, when actually its electric. if i remove the btu's that he had designated for it it brings me down to about 48k btu. does that sound more in line with what it should be?
     
  2. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    How does a propane water heater add 10k to house load? Do those things consume / leak that much conditioned air??? Holy cow!

    Conventional open center flue gas fired storage water heaters are efficiency dinosaurs.

    I hope one of the northerners can chime in with some hard numbers on that question.
     
  3. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    I am not way north but,

    I try very hard to eliminate standby DHW losses as the budgett allows.

    There could be an issue if the dealer based his sizing on total propane use. I am working on a design for a home near Columbus, OH and at 1300 gallons of propane last winter he used 28 million BTUs. There are other issues with this home besides DHW.

    I should be working on the project now, but am taking a break from training a new laptop.
     
  4. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Heat load.....water heater? Could the loss be same as a brick fireplace with no doors?
    What software was the calc prepared by?
    j
     
  5. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    How much propane did you use in the past? How efficient is your propane furnace? You can get pretty precise numbers from previous usage data.
     
  6. gbuck

    gbuck New Member

    Real close to 900 gallons every year. The furnace is 90% eff.
     
  7. gbuck

    gbuck New Member

    Real close to 900 gallons every year. The furnace is 90% eff.
     
  8. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Propane

    contains 91,800 BTUs per gal. Run the math.
     
  9. gbuck

    gbuck New Member

    OK that gives me 81million btuhs. What now?
     
  10. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Take away DHW usage and....

    .....that is the amount of BTUH IN that you need to heat your home to be comfortable. Divide that by heating degree days and that is your number.

    You could just run a heat loss and skip a few steps.

    I live in Ohio and have been doing goe, since Jimmy Carter, the worlds best, ______ or _____, and a very nice guy, was president.
     
    Last edited: Feb 16, 2011
  11. gbuck

    gbuck New Member

    ok, thanks everybody for all your input. its been very helpful.
     
  12. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    With 900 gallons and 90% efficiency, and your columbus ohio weather data, you are looking at less than 30,000 btu/h heatloss, which is more inline with a 10 year old 2100 sqf 2 floor building. Unless your usage numbers are incorrect, or you run your thermostat at less than 62 F right now but want to go up to 72 F with geo, a 3 ton system is more than adequate. It shows no aux heat, even with DSH factored in. Your heatloss was way off, again,assuming your usage numbers are correct.
     

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