any difference between gas and propane tankless water heater?

Discussion in 'Tankless Water Heater Forum' started by nothingeverworks, Mar 18, 2011.

  1. nothingeverworks

    nothingeverworks New Member

    Messages:
    38
    Location:
    Florida
    I'm making the change to a tankless water heater. Just wondering if there are any differences between gas and propane outside of the obvious storage and supply issue.
    thanks
  2. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,826
    Location:
    NW Ontario, Canada
    I would think the cost of propane would be the largest factor. As for other comparisons, propane is denser and generally provides a bit more BTU, all other things being equal. If the natural gas supply line is adequate, you can just up-size to get the needed BTU.
  3. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    The difference is "neithereverworks" Many studies show their life cost to be way over a tank type.
  4. Dana

    Dana In the trades

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    2,783
    Location:
    01609
    Show me the studies. (And not the crummy hatchet job from Consumer Reports, which was flawed beyond ball reason.)

    Be sure to inclued the underlying assumptions about fuel pricing, the cost of money, volume of use, incoming water temps, etc. This is not a no-brainer, at least in the gas-fired case.

    In the gas-fired case lifecycle cost can be break-even or slightly better for moderate use profiles in cool-water regions, but not necessarily for low-volume users in warmer areas such as FL. PG & E has done quite a bit of work vetting the lifecycle economics of gas fired tankless for their "typical" customers for the CA market, in part to determine the level of subsidy that the utility ought to cough up.

    But the financial argument is much easier to make when propane is the fuel, at something like 3-4x the cost per BTU.

    But lifecycle cost is usually way down the list the reasons why people go tankless. Item 1 is "endless hot water" (whether the reality lives up to the marketing fiction or not) and after that comes space-savings, etc.

    I'm not a big fan of tankless HW heaters either, but I'm not against them.

    There are very real differences between an LP and NG versions of the same model though- you need to buy the right version for the fuel used and set them up correctly, even if MOST of the components and sub-asseblies are identical. There are safety, efficiency, and heater-longevity issues that can be incurred from running it on the "wrong" fuel.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,802
    Location:
    New England
    At the minimum, there will be differences in the gas pressure regulator and the orifice or gas jet. Performance wise, once set up, may not differ much.
  6. Dana

    Dana In the trades

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    2,783
    Location:
    01609
    In some instances parameters in the control algorithms use by electronic controls will be different. In some models the fuel type is switch or jumper settable on the control board, leading to the erroneous impression by those who skipped the certifation training that it's the only adjustment to be made...
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