A tankless job

One item I would never have expected in a Woot-Off is a water heater, fercryingoutloud, but there it was, a little twenty-pound box that hangs on the wall and promises to keep you warm in the shower.

I wasn’t in the market — I’d replaced the water heater here last year — but I did pay attention to this little blurb in larger-than-fine print:

Not recommended in climates where average ground water temperature is less than 60°F. This unit draws 80 amps, please check your service panel for compatibility.

My gas water tank, of course, draws no amps. I concluded that this thing could melt down my 100-amp wiring in no time if I persist in such antisocial activities as turning on the lights. And what about that ground-water temperature? This document [link goes to PDF file] from the Office of Scientific & Technical Information had a tidy little map of such things, used for heat-pump analysis, and it appears the southern half of Oklahoma has a ground-water temperature averaging 62°F; the 57°F line more or less bisects Kansas. Florida and south Texas get into the 70s, while much of the Rust Belt is in the upper 40s and low 50s. Obviously this gizmo isn’t for everyone, though they did sell fifty of them in about twelve minutes. Inexplicably, there were buyers in Nebraska and South Dakota, way out of the 60-degree range; perhaps they’re buying them as backup systems.


  1. unimpressed »

    21 November 2008 · 8:34 pm

    It wouldn’t melt down your house wiring, though it would be advisable to run it on its own circuit. Had you not just replaced your water heater, this unit could possibly cost you less in the long run since it only runs on demand.

    I know people that have one and they figured that, even though the initial outlay is considerably higher than a water heater, the energy savings have recouped that outlay in less than three years.

  2. CGHill »

    21 November 2008 · 9:20 pm

    I use so little water around here — 2000 gallons a month is typical — that the tank I have pretty much runs only on demand; it uses maybe six, seven bucks’ worth of gas in a month. Still, these things are always pricey, and this one was made more so by the need to meet contemporary codes, which the old 1985 heater installation didn’t. Whether this cost more than setting up another 220 outlet (I have two), I couldn’t say.

  3. Francis W. Porretto »

    22 November 2008 · 6:54 am

    The principal application for such devices is in restrooms for small businesses in combo office buildings. Quite a number of commercial landlords are unwilling to provide pre-heated water to their lessors. Not being the direct employer, the landlord is not bound by OSHA regulations; thus, the burden falls on the lessor. These mini-water-heaters allow a small office with one or two small restrooms to heat the water for their sinks without the footprint or expense of a “traditional” water heater.

    I can’t provide specific figures, but I’d guess that the requirements for use on the better models are probably less stringent than the one you cited. At least, here on Long Island there’d be little market for a water heater that requires 60-degree incoming water — and I see them around here quite frequently.

  4. CGHill »

    22 November 2008 · 9:44 am

    Given the price point — Woot was selling these for $250 — this makes a certain amount of sense.

  5. Tatyana »

    22 November 2008 · 12:23 pm

    Chaz, does your water heater uses pilot with a small flame always on? Than it can’t be “on demand”; I doubt its gas usage is only $7 a month

  6. CGHill »

    22 November 2008 · 12:36 pm

    During the summer, it’s the only gas appliance in use around here, and per the meter, it uses about 0.8 to 1.2 dekatherms per month — which, at current prices, runs around $7. (The gas company, which has all manner of additional charges and fees and whatnot, manages to boost the monthly bill to around $20, but it’s still $7 worth of gas.)

    No, it’s technically not an on-demand device, but its gas usage is downright abstemious compared to its predecessor, which burned up half again as much of the stuff, and it helps that I don’t use all that much water, heated or otherwise. What’s more, I keep the thermostat down around 120°, which is plenty hot for my needs. (I don’t have a dishwasher and I am not fond of scalds.)

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