Would a second electrode help?

The Tank Would a second electrode help?

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  • #15091
    oilspot
    Participant

    Hello,

    We have a State Select Series ES6 80 hot water heater, purchased around October 2008. We purchased the house in September 2009.

    I recently discovered two things about this giant. First it only has a single 4500W element in the lower position. Second, it has a mounting hole for a second element in the upper position.

    One website said dual element WH are more efficient (a plus for me) and another web site hinted that the upper element may reduce the amount of cooler water near top of the tank reducing wait times for hot water. All of our faucets have about 1-2 minute wait to get warm water (I’m usually done washing my hands by then).

    Since the WH is so new, I can’t really justify replacing it (especially without the 30% credit for heat pump style). The tank has R16 foam insulation, so I was going to add additional insulation (I insulated all the pipes shortly after moving in).

    I think I can dig out a bit of the foam to find the wires and add a few more 10ga wires for the dual set-up. Then I can use some spray foam to seal the foam back up. I’m guessing everything will cost me about $100 (including the insulation).

    Does any of this make sense, or should I just grit my teeth and move on with other things? It is just two of us, but we like the extra capacity for guests when we host parties. Tankless would be ideal, but our house is all electric and I don’t think I have the spare ampacity for an electric tankless heater.

    #15092
    Randy Schuyler
    Keymaster

    Think about a Metlund D’Mans or a recirculation system. When you have a wait for hot water, it isn’t because the heater doesn’t have any. It’s because it takes awhile for hot water to travel through the piping to the faucet. Water in the piping cools off when nobody is using hot water.

    The Metlund is a pump that you activate by pushing a button and draws hot water through the pipes so you don’t have to run a lot of water down the drain.

    I’ll leave it to EnergyExpert to comment on the possibility of installing a second element.

    #15095
    oilspot
    Participant

    Thanks for the feedback about the pump. I have considered it on multiple occasions. My problem is the complexity of the plumbing and multiple branches. I’m very disappointed the plumbing was not designed more efficiently.

    The house is essentially a V shape with the hot water heater in the point of the V. The left leg of the V is single story with MBath. The right leg of the V is two stories with Kitchen, laundry and bath on first floor, guest bath on second floor. The basement is roughed in for bar and extra bath.

    All runs are 3/4 inch copper and 3/3 of the plumbing is running through unheated space or exterior walls. This was marketed as an Energy Star home with 2×6 walls, but it has been no more efficient than my previous house of traditional construction. I don’t know what the plumber was thinking…

    In studying the State water heater, I think I can “upgrade” it with an extra element, Mg anode, and a little more insulation. I was originally considering the AirTap heat pump add-on, but maintenance and reliability scared me. The new hybrids looked good, but the price and noise had me concerned (HW below MBR).

    So that’s how I got to where I am now, just trying to make my nearly new water heater a little bit better.

    #15096
    Larry Weingarten
    Participant

    Hello: Hot water floats on cold water, so you get hot water from the tank immediately on opening the tap. It won’t change at all with a second element. An upper element is useful when beginning from a cold start or when you have a very heavy draw of water. I agree with Randy that the D’mand system ( http://www.gothotwater.com ) is the right way to get hot water with less waste and wait. “Structured plumbing” could help also.

    Yours, Larry

    #15098
    oilspot
    Participant

    So adding a second element would not improve the energy factor of the hot water heater?

    I understand convection and conduction issues with hot water heating principles. It just seems like the two element units have higher energy factors. Is it all just insulation or do they get that extra 5% from the second element?

    The energy factor of my existing single element heater is 0.81.

    #15100
    energyexpert
    Participant

    One website said dual element WH are more efficient (a plus for me) and another web site hinted that the upper element may reduce the amount of cooler water near top of the tank reducing wait times for hot water. All of our faucets have about 1-2 minute wait to get warm water (I’m usually done washing my hands by then).

    Let me expand on what Larry said. Let’s assume your tank is completely cold. When power is turned on the element (in the lower region) heats all the water in the tank above the element level. So an 80 gallon tank may have 65 gallons above the element. A 4500 watt element will increase the temperature of 65 gallon 28F in one hour. Now look at an 80 gallon WH completely cold with two elements. When power is turned on the top thermostat powers the top element. Assume there is 20 gallons above the top element. A 4500 watt element will increase the temperature of 20 gallons 92F in one hour. This is what is termed “quick recovery”. You get a few gallons up to a useful temperature in a short time rather than waiting to heat a hold tank. After the top thermostat is satisfied the power is shifted from the top element to the bottom thermostat. Then the lower 45 gallons are heated.

    Does any of this make sense, or should I just grit my teeth and move on with other things? It is just two of us, but we like the extra capacity for guests when we host parties. Tankless would be ideal, but our house is all electric and I don’t think I have the spare ampacity for an electric tankless heater.

    “Extra capacity” can be achieved by increasing the WH temperature. This gives you more stored BTUs initially. The risk of scalding can be eliminated by plumbing in a mixing valve on the outlet of the WH. Set the WH to say 160F and set the mixing valve to 120F. The mixing valve mixes the 160F hot with enough cold to achieve 120F leaving the mixing valve.

    So adding a second element would not improve the energy factor of the hot water heater?

    I understand convection and conduction issues with hot water heating principles. It just seems like the two element units have higher energy factors. Is it all just insulation or do they get that extra 5% from the second element?

    The energy factor of my existing single element heater is 0.81.

    Electric WH elements are 100% efficient. The energy factor relates to total energy consumed including standby losses. The number of elements has nothing to do with EF.

    David

    #15108
    oilspot
    Participant

    Thanks for all the feedback and clear information. I did a thorough cleaning of the tank this weekend (to install a new drain valve) and got as much calcium out as I could. I thought the heater had a spiral inlet tube, but it was straight; so I see a new inlet tube and anode in my future.

    The existing element was so thick I could barely get it out of the heater. It was obviously a good time to replace it! On a whim I also added the second 3500W element in the upper location along with an upper (dual elelment thermostat). I understand it may not be more efficient but for an extra $20 in parts and an hour of my time, I figured what the heck.

    The longest part of the process was draining the tank (about 2.5 hrs). So I replaced the drain valve with a new full port ball valve.

    Once everything was complete, I added my home made insulation blanket, since it has been difficult to find a prefab blanket for an 80-gallon tank. (cost was $33 for R6).

    As everyone has said the extra element probably won’t help except maybe during high use or cold starts. However, I think the new “clean” element and insulation should help my heating and standby efficiencies.

    Thanks again for the feedback.

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