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Is this normal for a 30 gal lowboy?

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  • Is this normal for a 30 gal lowboy?

    I received a call from one of my customers yesterday, saying that his wife ran out of hot water after being in the shower for only 5 minutes. When I went there today the first thing I did was run the hot water over my thermometer to see how long the hot water would last. It was running out of a newer style Kohler lavatory faucet so I believe at full flow it was running about 2.2 gpm. (Obviously a newer shower head flows only about half of that). I had 130 degree water for a full 5 minutes then it started to drop in temperture slowly...about 3 degrees per minute. Is it normal for a 30 gallon lowboy with two 3500 watt elements(208 volts) to supply only 11 gallons of consistent 130 degree water for the first 5 minutes? I checked both elements and both thermostats....they all work fine. Doea anyone know if there's a chart from one of the manufacturers that will tell me recovery rates for different size water heaters with different elements in them? Thanks.

  • #2
    Re: Is this normal for a 30 gal lowboy?

    First off did you check the elements with and ohm meter or just a visual check? Also if it an older water heater sediment build up could be the problem. What was the thermostat set at?

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    • #3
      Re: Is this normal for a 30 gal lowboy?

      I checked them with an ohm meter and the heater is only 6 months old so not too much sediment was on them. The thermostats were set at 130.

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      • #4
        Re: Is this normal for a 30 gal lowboy?

        If you know the manufacturer their website will have recovery rates. Is it an energy saver model? They don't recover as fast as a regular Water heater.
        Last edited by EasyEman; 02-10-2009, 10:56 PM. Reason: mo info

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        • #5
          Re: Is this normal for a 30 gal lowboy?

          Recovery = Wattage / 2.42 X Temp. Rise in deg. F


          So lets do some math on the ole girl

          3500W / 2.42 x 130 deg. = 11.125 GPH

          So your answer is yes. Mike

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          • #6
            Re: Is this normal for a 30 gal lowboy?

            Mike, I appreciate the help but I think you were off on one thing. The stat is set to 130 but that is not the temperture rise. The temperture rise is 130 minus the inlet temp(about 80 degrees down here in FL). So the temp rise is 50 degrees. Thnaks for the formula though...I appreciate it.
            -James

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            • #7
              Re: Is this normal for a 30 gal lowboy?

              If i am not mistaken an electric heater will put out about what thier capacity is, thus the 30 gallon heater should put out roughly 30 gallons, I would say plus or minus 10. This is called thier first hour rating. I am curious about how you tested the thermostats. I would peg this for either a bad lower element and/or stat or a bad dip tube. With an electric heater only one element is on at a time. The upper thermostat has to satisfy before the lower is energized. During a long draw of hot water the lower element will become energized to heat the incoming water. In order to test the lower stat you would have to wait until the upper stat satisfies and then determine if signal is getting to the lower stat and then to element.

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              • #8
                Re: Is this normal for a 30 gal lowboy?

                bottom element is burned out and tank probably filled with calcium
                ANYONE CAN TAKE THE HELM WHEN THE SEA IS CALM.

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                • #9
                  Re: Is this normal for a 30 gal lowboy?

                  could the water saver have been pulled to provide more flow? If so, the flow rates you are figureing are going to be skewed.

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                  • #10
                    Re: Is this normal for a 30 gal lowboy?

                    I was considering the dip tube, but from my previous experiences if the dip tube is bad then you usually lose hot water quicker then I was. I checked both stats with an amp meter....first the upper which drew about 13 amps, then i lowered the temp on it and the lower stat kicked on...drawing close to the same 13 amps. I installed the heater about 6 months ago and it was on a Sunday when I had no A.O. Smiths on my truck so I had to get a GE from Home Depot. I put in some new 4500 Watt elements(about 4000 watt for 208 volts) and it now draws about 15 amps for each element. The faucet had the original aerator on it but I know that since this is the second floor of a 13 story condo, they get almost 90 psi water pressure.(Now that I think about it, I don't think they had a pressure reducing valve on the main). What is the standard faucets 2.2 GPM based on....60 psi?

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                    • #11
                      Re: Is this normal for a 30 gal lowboy?

                      Sounds like the heater is working fine. No water from t&p?

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                      • #12
                        Re: Is this normal for a 30 gal lowboy?

                        No, T& P is fine....everything seems to be fine, that's what's bugging me. I just called them and they said that they have plenty of hot water now.....hmmmmmmmmm now I'm really curious. All I did was change the elements to slightly higher wattage. Maybe the originals in the GE's are garbage, wouldn't that be a shocker! HAHA

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                        • #13
                          Re: Is this normal for a 30 gal lowboy?

                          The element can ground itself and still give you a good ohm reading.

                          I've seen elements go out on A.O. heaters in less than 3 months.

                          Sometimes you have to put in a higher wattage Sandhog or what I call a Wheelo element.

                          You probably took care of it with the higher elements.

                          J.C.

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                          • #14
                            Re: Is this normal for a 30 gal lowboy?

                            Is the cold on the inlet and the hot on outlet?
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