My plumber recommended adding a 2nd (50) gallon hot water tank(is not heated) to my system. The tank is acting like a reservoir only for recirculating hot water and is not connected to a heat source.
The tanks are connected in a series with the main cold water supply line feeding the unheated 50 gallon tank. This does not seem correct to me as cold water is going into the unheated reservoir instead of the 50 gallon tank that is heated???
Does not seem correct to me
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<Aunt May at the end of Spider Man: Homecoming> WHAT THE F---– Harper - Reinstate MonicaCommented Sep 28, 2023 at 21:12
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Why are you doing this?– JACKCommented Sep 28, 2023 at 21:15
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The description is not clear. Please make a simple schematic drawing of the plumbing layout, showing how it is now, and what the plumber proposes. Add the drawing to the text of your question using the "Edit" button below the question text, followed by pressing the "Moon and Mountains" button that appears over the text edit box. And, as @JACK correctly asks: do explain what problem you're trying to solve.– DavidRecallsMonicaCommented Sep 28, 2023 at 21:15
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3Community: Good point. This question reeks of an XY problem. You should state the root problem you are having, rather than guessing at a solution and asking about the solution.– Harper - Reinstate MonicaCommented Sep 28, 2023 at 22:34
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1The OP has a question, and it's clear without any diagrams. It's not an XY problem and the OP is not asking for advice on reasons to install a storage tank. I've learned that in SE when people say "it's an XY problem", they mean that they don't know the answer. The actual OP question has been answered.– CheeryCommented Sep 29, 2023 at 0:13
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1 Answer
So, you have a recirculation system on your hot water. Which means that at some point, tepid water comes back from faucets - how often depends on how the system is set up. Most don't run all the time, as that's very wasteful due to the pipes usually not being nearly as well insulated as the tank is.
By bringing the fresh cold water into the tank with the tepid water from recirculation, and then sending water from the tepid tank into the heated tank, the water entering the tank with the heaters is warmer, as the tepid water will sit on top of the cold water. That gives you a bit more capacity on the heating, because tepid water takes less heating than cold water.
There's nothing wrong with plumbing it that way, despite a rash of extreme comments. But it may not give you much additional capacity, either.
answered Sep 28, 2023 at 23:47
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This is the correct answer. I'm no plumber, but I've seen enough plumbers install these storage tanks, and they always install the cold water supply into the storage tank, not the heater. For example, look at the piping diagram here: aosmithme.com/wp-content/uploads/2019/02/…– CheeryCommented Sep 29, 2023 at 0:03
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This answer makes sense of what was a very confusing question. I have to wonder, however, just how much it really helps and if it's truly "worth it" in the long run. (Yes, I realize that's a 2nd, new question, and that if I were to ask it, it would be summarily shut down as "opinion based". I supposed I could ask "by how much" does this arrangement save money/energy/whatever.)– FreeManCommented Sep 29, 2023 at 14:25
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In most houses, turning the recirculation off will save money and energy, while wasting a little water and time as you wait for the water to run hot at the tap - how much depending on how far it is from the heater to the taps. The additional tank with recirculation will boost the amount of hot water you get before you run out of hot water by an amount depending on the typical temperature of the tank from recirulated hot water .vs. the incoming water temperature. The boost will be less than having a second tank that's heated, but will also take less energy input than a second heated tank.– EcnerwalCommented Sep 29, 2023 at 14:50
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It's the sort of thing that would really require some detailed data-gathering to quantify, and I don't know if any of the various research-house setups have looked at that exact question. And if they have, the details of how it's set up/controlled would affect the outcome, if I understand the problem correctly. You could get a lot more capacity by circulating more, but you'll waste a lot more energy from the pipes doing that. At some point it might logically cross over to heaters in the second tank and no recirculation saving energy, but not water, if more capacity was what's wanted.– EcnerwalCommented Sep 29, 2023 at 14:52
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Note that recirculating if/while you are heating isn't wasteful, so long as your heat and hot water use the same fuel, unless you have a heat pump, in which case your hot water could be a bit more expensive.– dandavisCommented Sep 29, 2023 at 15:39