Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Recommendation for reliable, exterior, gas tankless water heater

ak540235
ak540235 Member Posts: 3
in Domestic Hot Water
Hello!

I am retrofitting a 500 sq. ft. studio (ADU) in the San Francisco Bay Area. I'd like to replace the existing water heater tank and reclaim the utility room that it's in by installing an external tankless water heater. The studio has 1 kitchen sink, 1 bathroom sink and 1 shower.

Any suggestions for which models are most reliable and suitable for exterior use for a small space?

Thank you!

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 25,157
    Step 1-- make sure you actually can install a new gas fired unit...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    kcoppIntplm.
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,628
    Hi, I agree with Jamie. California is aiming to get off of gas by 2035. If you used low flow fixtures and a shower drain heat exchanger, you could probably get by nicely with a 20 gallon electric tank, which could fit under a sink or other snug places. Of course, this depends on how many people the system would serve. Just for doing some of the math, the average shower is eight minutes and low flow showerheads can be adjusted to deliver 1.5, 1 and .5 gallons per minute. This suggests a 20 gallon tank could give you about two showers. With a shower heat exchanger, easily three showers o:)

    Yours, Larry
  • ak540235
    ak540235 Member Posts: 3
    Unfortunately the space is on a single 20A circuit, so I'd have to spend quite a bit to upgrade electrical for a non-gas solution.

    Right now I'm looking at EnergyStar UEF >= 0.95 rated, outdoor gas tankless water heaters.

    Currently narrowed down to:

    Takagi T-H3J-OS-N $979
    Rinnai RU160eN $1,395
    Bosch T9800 SEO 160 Outdoor $1,496
    Navien NPE-180S2 $1,275

    These are all overkill for my small space, but only the larger models seem to meet the EnergyStar rebate criteria. Any opinions on these models?
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,628
    Hi, I looked up rebates here: https://programs.dsireusa.org/system/program/detail/1274/residential-energy-efficiency-tax-credit You might double check, but all I see is a $300 tax credit. Might be tail wagging the dog... Another thought about the electric approach is to run the water heater at 120 volts. This way it draws 1/4 the power it needs at 240 volts.

    Yours, Larry
  • ak540235
    ak540235 Member Posts: 3
    Thanks, Larry. Here is the rebate I'm thinking of:
    https://www.energystar.gov/about/federal_tax_credits/tax_credits_homeowners/water_heaters_natural_gas_oil_propane

    30% or $600 for tankless gas water heaters; ENERGY STAR models with > 0.95 UEF are eligible.

    I'll get a quote for the electrical upgrade, but I think it would require a new panel and possibly even a service upgrade from PG&E.

Categories