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Thread: Running out of hot water with a 60G tank

  1. #1
    DIY Member benze's Avatar
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    Default Running out of hot water with a 60G tank

    I've got a 60G bottom feed electric hot water tank that recently seems to be running out of hot water sooner that I would have liked. It has 2 gravity feedback loops on it that normally work fine. I checked the elements and they are both working properly, so I suspect it is more a question of water usage than anything else. The HW temp is set to be about 130-135F. The reality is that I don't have cold water coming out of the faucets; just warm. So I figure that although it is a 60G tank, I presume that under a constant use, I can't actually get 60G hot water out, but rather only 20-30G before the influx of cold water into the tank brings down the temperature too much.

    If my theory is correct, I figure the best I could do would be to raise the water temp before it goes into the tank, to reduce the temperature differential and the drop. So I'm wondering if I were to add a tankless system on the supply to warm to 70-80F, it should help reduce the thermal shock and provide me with more hot water. I live in Montreal, Canada, so the supply in winter is probably somewhere around 35-40F.

    Is this a logical solution? Or is this a bad concept - more of a bandaid solution but not fixing the problem itself? Is there a better way to approach the problem?

    Thanks!

    Eric

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    Moderator & Master Plumber hj's Avatar
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    IF your tank is set for 135 degrees and you only have warm water coming from the faucets, you DO have a problem but it is not because of the water heater size. We would have to do our own testing to find out WHY the water is not HOT. I would also want to know HOW you determined the elements are working "properly". But it is probably because the 'feedback loops" have gone bad.
    Licensed residential and commercial plumber

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    DIY Member benze's Avatar
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    Quote Originally Posted by hj View Post
    IF your tank is set for 135 degrees and you only have warm water coming from the faucets
    Like I said, I do have hot water at the start. After a while (giving kids a bath, washing dishes, etc), it becomes warm. Too quickly for my taste, but it could well be that I've just drained too much hot water too quickly.

    I would also want to know HOW you determined the elements are working "properly".
    I turned of the HW tank, detached the elements and tested their resistance. I do not remember the exact number, but they were not open circuit. Given I changed the lower one about 4 or 5months ago, and the resistance reading of the bottom and top elements were similar, i presume them to be properly functioning. Then, with the power back on and everything reconnected, I verified that I was getting 220V at the elements when the tank was heating and sure enough, both are being energized.

    But it is probably because the 'feedback loops" have gone bad.
    How does a feedback loop "go bad"?

    Thanks,

    Eric

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    DIYer, not in the trades LLigetfa's Avatar
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    The only proper way to diagnose an element is by measuring the current drawn.

    So what exactly are feedback loops? Are they a recirc to give you instant hot water? Aside from a bad element, thermostat or dip tube issue, change in usage is the most plausible explanation. One way to get more hot water is to raise the temperature and then use a tempering valve. They make special ones for recirc systems, but I don't know if that includes gravity types.

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    Jack of all trades DonL's Avatar
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    Quote Originally Posted by benze View Post
    Then, with the power back on and everything reconnected, I verified that I was getting 220V at the elements when the tank was heating and sure enough, both are being energized.
    Eric

    Not sure what model you have, But that does not sound correct for both elements to be heating at the same time.

    I am not sure what "energized" is for sure. Is your tank Grounded ?

    You may want to evaluate your testing methods.

    Be careful playing with Electricity.


    Good Luck.
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  6. #6
    DIY Member benze's Avatar
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    Quote Originally Posted by LLigetfa View Post
    The only proper way to diagnose an element is by measuring the current drawn.
    Agreed... I was going the lazy way :-) I don't have a clamp meter handy and didn't want to wire up my multimeter to it so figured this would be a safe cheat. Presuming know the resistance and the voltage, amperage simple math. I just don't remember the resistance value.

    So what exactly are feedback loops? Are they a recirc to give you instant hot water?
    Yes; they were added provide instant warm-to-hot water the faucet.

    What is a dip tube issue? Where is the dip tube located? In the tank?


    One way to get more hot water is to raise the temperature and then use a tempering valve.
    Well two things come to mind. 1) extra expense ofconstantly heating to a higher temp. 2) what will that accomplish? Just raising the internal temp and tempering at the faucet would imply that I want to minimize the impact of the cold source. In which case is it not a better idea to raise the temp of the source?

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    DIY Member benze's Avatar
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    Quote Originally Posted by DonL View Post
    Not sure what model you have, But that does not sound correct for both elements to be heating at the same time.
    Can't say for they were both heating at the same time. I saw 220 on the bottom one and a few mins later 220 on the top one.

    I am not sure what "energized" is for sure. Is your tank Grounded ?
    Energized: 220V across terminals
    Yes, it is properly grounded

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    Forum Admin, Expert Plumber Terry's Avatar
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    The top element goes on first, and when the top of the tank is heated, power is transferred to the lower element.
    They never come on at the same time. Recovery is about 25 gallons an hour. Once it's being used, you go through the first 60 gallons, then you have just a little bit of recovery with electric. A bath can be a lot of water. Hand washing dishes can drain a tank pretty quickly too. A dishwasher is much more efficient with water.

    I've got a 60G bottom feed electric hot water tank


    The dip tube is normally below the input. A plastic tube that may or may not be intact. If you have little bits of plastic showing up in faucet aerators, then the dip tube is coming apart.

    Since you have a bottom feed tank, that is the "dip tube". Where it enters the tank.

    You can juice a bit more water out of the tank "safely" by adding a tempering valve and running the heater on high, blending down the output to a safe range for bathing.

    http://www.terrylove.com/forums/show...er-tempering-)
    Last edited by Terry; 12-08-2013 at 09:10 AM.

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    Jack of all trades DonL's Avatar
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    I am not sure a bottom feed tank would need a dip tube ?


    What is the model number ?
    Theory only works perfect in a vacuum.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    If you recirc lines don't have a checkvalve, or the checkvalve is no longer working, when drawing water from the tank, water will flow through the path of least resistance, which may very well include from the (colder) bottom of the tank AND from the hotter top of the tank, resulting in a much cooler mix than what it could be.
    Jim DeBruycker
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    DIYer, not in the trades LLigetfa's Avatar
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    Jim makes a good point about the the loops possibly reversing, but that should result in diluted water from the get-go. Another possibility is a crossover situation but that too, would manifest from the get-go.

    Another possibility is a leak where hot water is being lost. Some folk may go for months before noticing the higher electric and water bills.

  12. #12
    Retired Defense Industry Engineer jadnashua's Avatar
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    If the WH hadn't been used for awhile, you'd have hot water at both the top and the bottom, so you might not notice a mix. Shortly, though, as you draw in cold to replace what's there, it would cool off fairly quickly if there were no functioning checkvalve(s).
    Jim DeBruycker
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    DIYer, not in the trades LLigetfa's Avatar
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    I think you are basing your theory on the cold supply entering the bottom of the tank in a different place than the return side of the loops. Without a definitive from the OP, it is conjecture.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    If I remember, he said his cold inlet was low, rather than being on top like it is on many tanks with a dip tube.
    Jim DeBruycker
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    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIYer, not in the trades LLigetfa's Avatar
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    How many bottom ports would there be on a HWT? I am going on the assumption that the same one is used for the cold feed as well as the loop returns. So, if the loop was reversing, the cold would split in two directions, some of which would feed the HWT and the rest backfeed through the loop return. I would not expect blending in the bottom of the HWT.

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