Short gas water heater, lowboy?

Discussion in 'Water Heater Forum, Tanks' started by Edward Jockers, Nov 15, 2012.

  1. Edward Jockers

    Edward Jockers New Member

    Messages:
    1
    Location:
    new york
    I'm looking for a gas hot water heater to fit into a four foot high crawl space, the height being an issue, for venting purposes, i'm looking possibly for a low boy, forty or fifty gallons.any ideas? Thanx
    Last edited by a moderator: Nov 15, 2012
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,917
    Location:
    New England
    Lowboys are getting harder to find. As an aside, if your water was hot, why would you need a heater? Now, maybe calling it a cold water heater might be more appropriate, since cold water getting heated is a nice idea, but it's really just a water heater. It's one of those English teacher things that just throws up a red flag and almost hurts...

    The codes now require (nearly?) all residential water heaters to protect against vapor combustion - i.e., it will prevent flamable vapors that might be around the WH from igniting, or if it does, restricts it so the flame doesn't get outside of the WH. This is to prevent you from blowing up the house if you happen to store some flamable liquids near the WH. This means that for the same volume WH tank, it will be taller since the new stuff has to enclose the burner assembly. Electric low-boys are likely more readily available, but your cost to heat will often be 3-4x what gas costs. So, your choices are likely to be really restricted, if they exist at all. Big diameter, low height is less efficient when heating the water, too, and recovery times would likely be slow. On a gas WH, the length of the heat exchanger (and flue in the thing) determines how efficient it can be...make that short, and it may not be able to meet the minimum federal efficiency standards or it becomes MUCH more complicated to manufacture and design.
  3. Terry

    Terry Administrator Staff Member

    Messages:
    14,904
    Location:
    Bothell, Washington
    You could also go with a tankless water heater if space is an issue.
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,917
    Location:
    New England
    What kind of space heating do you have? If you have a boiler, verses a furnace and hot air, there are LOTS of indirect WH that would fit.

    Tankless can work, but depending on where in NY you live, your incoming cold winter water temperatures may approach freezing (mine does in Southern NH). This means you have a choice of low volume hot water in the winter, or a fairly big unit(s)...you can only raise the temperature of water flowing by so much with a fixed amount of heat - think hand through the flame of a candle...it only hurts if you go slow, same with the water passing by the heater. You either need a blowtorch (big unit(s)) or settle for a lower max volume. You may also need to upgrade your gas line, or at least the line feeding the thing. Then, they have an annual maintenance that generally must be done, or their performance drops as they accumulate mineral deposits (think teapot or coffee pot - mineral deposits happen when you have high temps and hard water). It can get much worse on the insides of a WH. They do work, are generally much smaller, but to set one up right with few or minimal inconveniences, does cost more than a tank, sometimes, lots more.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,508
    Location:
    Cave Creek, Arizona
    quote; Now, maybe calling it a cold water heater might be more appropriate, since cold water getting heated is a nice idea, but it's really just a water heater. I

    it is ONLY a "cold water heater" for a few minutes, then it becomes a "tepid water heater", then a "warm water heater", then a "warmer water heater", then a "hot water heater", and depending on the thermostat setting it then become a "very hot water heater". IF the thermostat fails then it becomes a "steam heater" and finally a "house demolition/improvised explosive device". The heaters are not always taller, because some companies have eliminated the legs to reduce the height. Because the flue ALWAYS comes off the top of the heater, it would have to be about 36" high in order for the draft diverter and an elbow to fit on top of it. Take away about 12" for the burner chamber an you wind up with a tank about 24" tall. Doing the math, you would have a tank about 40" wide, allowing for insulation by 36" high. If you had a single flue passage, it would be very inefficient, considering the short heat transfer time and the small percentage of the water in contact with the flue. The shortest 40 gallon heater I know of is 50" high by 20" in diameter.
    Last edited: Nov 15, 2012
  6. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,918
    Location:
    NW Ontario, Canada
    Why not just call it a water heater without all the superfluous stuff?
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,917
    Location:
    New England
    Well, is it a 'hot' water heater if it's off? Tongue in cheek...it's a water heater if it's doing its job - making water hot. It's all about where the adjective is and what it is describing.
  8. Terry

    Terry Administrator Staff Member

    Messages:
    14,904
    Location:
    Bothell, Washington
    The plumbers call the "water heaters"

    So like.........what was the question?
    Last edited: Nov 15, 2012
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