Outdoors on demand propane water heater 199,000 btu advice

Discussion in 'Tankless Water Heater Forum' started by hydrocynus, Dec 30, 2019.

  1. hydrocynus

    hydrocynus New Member

    Dec 30, 2019
    Fort Myers, FL USA
    Hello all,
    I live in southwest Florida and we are finishing our home. We are going to be using liquid propane for the water heater. The the guy installing the buried tank and setting up the gas lines advises us to get a Navien NPE240A.

    However, I also have seen that Takagi and other brands are also available. They also are cheaper. What would you guys advise me to buy and why? I know nothing about water heaters but I am willing to learn.

    Thank you very much for your help!

    PS> I wished I could convince my second half on a solar water heater (the one with coils) but I have been unsuccessful.
  2. Dana

    Dana In the trades

    Jan 14, 2009

    In SW Florida a heat pump/hybrid electric water heater and a couple of PV solar panels on a grid-tied inverter beats any solar-thermal water heating system on cost & performance, if your utility does net-metering of the solar power.

    In your area heat pump water heater in a carport or shed (without the roof top solar) would likely have a lower operating cost and definitely better flow than propane tankless too.

    What is your local average price for propane (not the cheap introductory new-customer price) ? Is it too late to pass on the buried tank?

    What are your all-in fully delivered electric rates? (<<is the 10.4 cents accurate?)

    Even at $2/gallon for the propane, at 97% efficiency you're getting 0.97 x 91600 BTU/gallon= 88,852 BTU/gallon. Normalized to million BTU(MMBTU) that would be 1M/88,852= 11.25 gallons/MMBTU

    At $2/gallon that costs $22.50/MMBTU.

    At the current FL average $4/gallon that's $45/MMBTU

    At 10.4 cents/kwh and an UEF of 3.5 in a heat pump water heater (you can probably do better than that in your location if mounted outdoors or in a semi-open space) it would deliver 3.5 x 3412 BTU/kwh= 11,942 BTU/kwh. Normalizing to MMBTU, that would be 1M/11,942= 84 kwh/MMBTU.

    At 10.4cents/kwh that costs $8.74/MMBTU

    That is well under half the cost of hot water with $2 propane in a condensing water heater, and about 1/5 the cost at the state wide average of $4/gallon.

    Even if electricity hits 20 cents (not likely) you'd still be getting cheaper hot water with the heat pump water heater.
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  4. Dana

    Dana In the trades

    Jan 14, 2009
    See my response to your mini-split recommendation thread. In your house you definitely want to use a heat pump water heater (not an outdoor propane unit), but installed indoors in fully conditioned space.

    That house going to have a 12 month cooling season. With a heat pump water heater in a 75F room about 3/4 of the heat going into the water is coming directly out of the conditioned space, lowering the indoor humidity (by significant amount) and the room temperature (by a small but measurable amount), which is effectively equivalent to "free" hot water, since it directly lowers the cooling load, but more importantly, it's mostly removing latent cooling loads, which are hard for the air conditioning to keep up with when the sensible cooling loads are so small compared to a "normal" house that size.

    A 50 gallon Rheem Performance Platinum heat pump water heater is enough water heater for most families. If you have a large soaker tub to fill it might need something bigger. There are others. A nice feature of the Performance Platinum series is it's already set up to have the ability to duct the cold-air output and room-air input to/from locations where it does the most good when it's running from a cooling load balancing point of view. They are also quieter than some of the competition, even quieter than some refrigerators.
  5. DavidHun

    DavidHun New Member

    Nov 10, 2019
    New York
    If you want an on-demand I'd recommend taking a look at Rinnai v65 from this propane tankless water heater guide. It's not the best model if you're looking for cheaper options, but still a good one.

    Otherwise, just go with the advice posted above ^_^
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