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Powering Electric Water Heater w/Generator

Post in 'DIY and General non-hearth advice' started by thinkxingu, Oct 4, 2010.

  1. thinkxingu

    thinkxingu Minister of Fire

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    The 4500 was quoted somewhere online as the power required for a hot water heater, but my actual heater says 3800 top and bottom. Looks like there was an option to have 3800 bottom and 4500 top.

    S

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  2. Cowboy Billy

    Cowboy Billy Minister of Fire

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    We are going to hook up to either a 2lb or 100lb propane tank. No need to hook up to city gas or listen to a generator run long enough to heat a tank of water.

    Billy
  3. vvvv

    vvvv New Member

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  4. Tarmsolo60

    Tarmsolo60 Feeling the Heat

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    2 element tanks have only one element at a time operating, the top element always priority over the bottom element. This gives the user faster recovery for useable hot water when the tank is depleted of hot water.

    3800 watt elements are for a 20 amp 240 volt circuit

    4500 watt elements are for a 30 amp 240 volt circuit

    If it were me, I would start the water heater an hour before I need it for showers, then let it run until the load is off the generator after the showers(you should be able to hear that on your generator). That would probably provide you with enough hot water until you start it again an hour before showers the next day.
  5. vvvv

    vvvv New Member

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    so whats the swithing mechanism which tells top element to burn & not the bottom?
  6. Tarmsolo60

    Tarmsolo60 Feeling the Heat

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    The top thermostat must be satisfied temprature wise before it will transfer power to the bottom thermostat.
  7. vvvv

    vvvv New Member

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    & so a "quick recovery" is better acheived by fewer watts from 1 element?
  8. Tarmsolo60

    Tarmsolo60 Feeling the Heat

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    a 2 element (quick recovery) tank will heat the top third of the water heater first to give the user access to hot water faster, then transfer the power to the lower element to heat the remainder of the tank.

    If you have a 2 element or a single element tank and the thermostats settings are equal then when both are done heating they will have used the same amount of energy. given the starting water temp, insulation are equal.

    The only benefits to a two element tank is giving the user faster access to hot water when the tank is depleted of hot water. Or maybe some access to hot water when the lower elenet burns out.
  9. vvvv

    vvvv New Member

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    ignored this?& so a “quick recovery” is better acheived by fewer watts from 1 element? say so dont make it so! water heater will recover quicker from 2x the wattage, duh, u can reset the thermostats to whatever temp & they"ll react accordingly & INDEPENDENTLY...........your mechanical switching mechanism is yet to be revealed too
  10. Tarmsolo60

    Tarmsolo60 Feeling the Heat

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    Top thermostat only allows one element to heat at a time.
    Qick recovery is better achieved by heating 1/3 of the water to usable temp first.Duh

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  11. vvvv

    vvvv New Member

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    thanx, new 2me. still, if both elements came on it would heat faster even with this setup, though it might trip the circuit breaker.
  12. Highbeam

    Highbeam Minister of Fire

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    Sure, if both elements fired simultaneously you would be providing more btus per hour and tank tamp would rise faster. However, you would overload the circuit. You could put ten elements in and really get hot water fast, instantly even. Heck, get rid of the tank and use an instant electric tankless water heater if you have that much power to spare.

    If you know that only one element fires at a time, then your 5500 genset can heat the water. It doesn't matter when you run the genset but nobody likes to hear one all night. I would tend to heat the water right before use but would rather allow two hours for heat up if the tank is full of cold water. You'll hear a 3800 watt load turn on and off.
  13. thinkxingu

    thinkxingu Minister of Fire

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    I actually hadn't thought about shutting the generator off at night, but I suppose there's no real reason to run it other than the fridge and lights if we need to get up. Anything I'm missing?

    S
  14. Highbeam

    Highbeam Minister of Fire

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    We always shut down at night. Nothing quite like the silence of a house with no power. Your gas 5500 watt genset will be consuming a LOT of gasoline when running whether it is loaded or not. No sense in running the genset and wasting that gas all night. Keep the fridge closed and do all your business before shutting off the genset and enjoying the evening watching the fire or sleeping soundly. Start it up in the morning to cool the fridge and to run the lights for your morning chores. You will have saved 8-10 hours of run time which is at least 5 gallons of gas, no ill effects. Honestly, I'll even shut down the genset in the middle of the day if there is no need for it. Conserving fuel can be extremely important if the outage might last more than a day. What if it was for a week and you only had 20 gallons of gasoline (not many have more than 5)? You'll want to ration your usage.

    These things suck lots of fuel. Really, lots of fuel so don't just run the genset for fun.

    Oh, and you'll need to look outside at your neighbors or check your own panel to see if the grid is back up.
  15. thinkxingu

    thinkxingu Minister of Fire

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    Highbeam,
    Makes sense, thanks. I think I'm gonna look into that device that indicates power has come back--there's a wire that wraps around the main in or something?

    S
  16. daveswoodhauler

    daveswoodhauler Minister of Fire

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    Same thing Highbeam said.
    Run it during the day when needed, and shut down at night...don't wanna hear that thing purring at 3:00am :)
    During the Icestorm of Dec 2008 we lost power for 8 days....up here in NEw England thats tough....especially when you are on well water.
  17. fbelec

    fbelec Minister of Fire

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    they do make fast recovery electric water heaters for commercial use. they are usually 120 gallon tanks with 3 upper elements and 3 lower. they are setup on a 70 amp circuit for single phase (residential) power or 30 amp 3 phase. they recover quick with 3 elements. stone cold 3800 watt elements heaters take a month of sundays to heat. 4500 watt which is standard wattage take 45 minutes to come up. commercial 3 element heaters take 15 to 20 to heat. and that's 120 gallons.
  18. thinkxingu

    thinkxingu Minister of Fire

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    Interlock installed, outside outlet installed, water heater changed from second-meter-disconnect to main panel, inspection tomorrow. Inspector said to just leave the H20 heater on when genny running--will not draw like a motor and the rest of the stuff I'll be running (fridge, couple lights, etc.) won't pull enough to tax the generator. Finally, 'it takes more power to heat up a cool tank than it does to maintain a hot one.'

    S
  19. vvvv

    vvvv New Member

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    no way it takes more power to heat a cool tank than to maintain!.........whered u get that?
  20. thinkxingu

    thinkxingu Minister of Fire

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    Maybe that was worded wrongly: 'Heating up a cold tank will draw the same power, 3,800 watts, but for a longer time than if the tank heat was maintained.' Do you disagree with that? I know it takes more overall power to heat up a cold house than to keep one warm.

    S

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