Hot Water heater sizing question

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by ron in sc, Feb 28, 2008.

  1. ron in sc

    ron in sc New Member

    South Carolina
    I need to install water heater for detached garage, it will have to be electric.

    How big a tank to I need? It will need to supply hot water to following:
    -front loader washing machine, used only to wash items used in connection with use of garage
    -shower; which will be used infrequently
    -outside spigot; also used infrequently
  2. jimbo

    jimbo Plumber

    San Diego
    A 30 gallon would be fine for the WM and shower, although a 40 doesn't cost much more.

    A hose bibb will suck an 80 gallon dry in about 4 minutes!
  3. ron in sc

    ron in sc New Member

    South Carolina
    I do have a spigot next to it that is regular water, if I do use the hot water to wash really dirty stuff like boat it sounds like I should make a connnection between the two so I can mix the hot water with the cold.

    Also what do you think about those hot water heaters that have can be set for a few different modes. One of the house hot water heaters has that it's a Whirlpool and has this thing on top that say energy smart. Are they just a gimmick? Maybe one of those would be good in the garage too.
  4. Squ1rrel

    Squ1rrel New Member

    Those energy smart panels are supposed to track usage and only keep water hot during the times you most use it...not sure how well it would work if you use different amounts at changing times. Plus it's a Whirlpool..with all the problems with their gas WH's, I'd be leery of their electrics too.
  5. Bob NH

    Bob NH In the Trades

    New Hampshire
    "Energy smart" on an electric water heater is a gimmick. They have such good insulation, and such poor recovery rate, that controlling the heating on a 24 hour cycle would be a hopeless exercise.

    The only "energy smart" that would mean anything would be if you were getting a special rate from the power company for off-peak power. If that is the case there should be a power company clock system that would allow them to shut off the lower element during peak (high rate) times.
  6. Herk

    Herk Plumber

    S.E. Idaho
    50 gallon may be as cheap or very nearly the same price as a smaller heater. Paying more for efficiency is a very good idea - better insulation saves money. Paying for silly electronic gadgets and hype is not a good idea. (Not yet, anyway. Maybe someday they'll actually implement such things effectively.)
  7. ron in sc

    ron in sc New Member

    South Carolina
    Is it cheaper as far as electricity goes to use a smaller tank, since it should take less electricity to keep less water hot?
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    New England
    Not necessarily. The exterior surface area difference between different size water heaters isn't quite linear, so a bigger WH has less exterior surface area to radiate out heat from than a smaller one. The quantity and quality of insulation makes a big difference. WIth an electric WH, you have nearly 100% efficiency in heating, but your standby loss is determined by the quality of the insulation and the area that acts like a radiator.
  9. chawk

    chawk New Member

    Charlottesville VA
    I'd go with the 50 gallon, you must have a nice setup, and or income to have a detatched garage with a washer and dryer just for the garage. :) but hey more power to you.
  10. get the 50 and install a breaker switch.

    Get the 50 gallon and put the blanket on it...

    Stay AWAY from that Energy smart heater...,,
    it is a piece of junk and will eventually give you troubles

    Get a GE from HD

    Now if you really want to save energy in the garage,

    install a breaker or a breaker junction box with a lever
    right next to the water heater....
    and just turn the water heater on only when you need to
    on the weekends or an hour before the action begins....
    instead of heating the water 24 hours a day.....

    it will literally heat up in about a half hour ..
    Last edited: Apr 12, 2008
  11. Redwood

    Redwood Master Plumber

    Sounds like the perfect environment for legionella!
    The water should be in the prime growth zone for about all week!

    On a lighter note I would suggest this sillcock for hot/cold water mixing. Just using a wye hose cold be a cross connection that among other things could crack a toilet.

  12. you think it would ???

    I never considered some funkey bacteria
    growing in the tank......even on city water

    I suppose that is a possibility, however so slight...
  13. Redwood

    Redwood Master Plumber

    I do not advocate turning off the heat on a water heater. This will increase the danger if Legionaires desease.

    The biggest single threat from tepid water is probably legionella.

    70 to 80 °C (158 to 176 °F) - Disinfection range
    At 66 °C (151 °F) - Legionellae die within 2 minutes
    At 60 °C (140 °F) - Legionellae die within 32 minutes
    At 55 °C (131 °F) - Legionellae die within 5 to 6 hours
    50 to 55 °C (122 to 131 °F) - They can survive but do not multiply
    20 to 50 °C (68 to 122 °F)- Legionellae growth range
    35 to 46 °C (95 to 115 °F) - Ideal growth range
    Below 20 °C (68 °F) - Legionellae can survive but are dormant

    Many of the states and at least some of Canada are now requiring water heaters set at 140 Degrees F and a tempering valve on the outlet to lower the water temp to 120 Degrees F. I would expect that this will be a code requirement everywhere before long.

    Have a look see at this link...

    Last edited by a moderator: Jan 28, 2011
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