Does anyone have experience using a series of smaller tanks (maybe old 100 gallon propane tanks) for heat storage. Basement space is limited for me, but I think I could get a bunch of smaller tanks into an arrangement.
Water Storage (Smaller Tanks in Series)
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Others will chime in but I don't think this would be a particularly efficient way to use thermal storage. There are many discussions here regarding "stratification" which is the seperation of hot and cold water inside your tanks. With a bunch of small tanks you'd limit your ability to separate and you'd have more mixing, I believe. You'd also have a lot more plumbing to work through.
Is it better than no storage? Not sure. Perhaps it would depend on the way you plumbed them and/or stacked them...
Is it better than no storage? Not sure. Perhaps it would depend on the way you plumbed them and/or stacked them...
I think the use of a bunch of small tanks might actually improve heat separation. With a single tank, heat conduction is going to tend to remove stratification. With multiple tanks there is a much smaller heat conduction path between the tank so the hotter tanks (i.e at the beginning of the tank charging path) will be less likely to spread heat to the cooler tanks.
The million dollar question here is whether tanks stratify due to the density differences between hot and cold water, or due to the direction of the flow when charging/discharging. It is probably a combination of both, but I think the manner in which the tank(s) are charged/discharged is much more important.
If you had a tank of water with uniform heat throughout, I don't think it would self stratify. If you had a tank with hot water at the bottom and cold water at the top, I don't think it would flip-flop. I think it would just mix and become even. My point is that heat separation won't just happen on its own, and convection (which is what you'd really lose with multiple tanks) is not really good for stratification.
The million dollar question here is whether tanks stratify due to the density differences between hot and cold water, or due to the direction of the flow when charging/discharging. It is probably a combination of both, but I think the manner in which the tank(s) are charged/discharged is much more important.
If you had a tank of water with uniform heat throughout, I don't think it would self stratify. If you had a tank with hot water at the bottom and cold water at the top, I don't think it would flip-flop. I think it would just mix and become even. My point is that heat separation won't just happen on its own, and convection (which is what you'd really lose with multiple tanks) is not really good for stratification.
I thought I saw a setup somewhere on the net where a guy had a bunch of tanks in series. He had described a setup of 3 where one tank is really warm, the one in the middle is medium, and the other is cooler. He extended this idea into a long line of tanks. Anyway, I'm a carpenter and not a plumber so I know I'm bugging you boiler-roomers with some basic stuff.
The physics here could be mind numbing if you let it be. I know in my 500 gallon tanks I can get some crazy reactions in temperatures based purely on flow. For example, when I have no calls for heat from the house and I'm pumping 100% of my 180 degree water into the top tank I can actually see temp drops on my upper sensors at the end of the tank simply from the "wave" the circ pump flow is creating in the tank at the top. It's super strange. How your heat transfers depends on so many things not to exclude at which point in the tank you inject the hot water and at which point you remove the cold water. Insanity I tell you...
Yes, after several semesters of calculus and a thermodynamics course, I was able to take a heat transfer class where we learned that even the simplest of heat transfer problems require complicated differential equations and the non-simple problems (i.e. anything in real life) are too complicated for a human to even write the equations, let alone solve them.stee6043 said:
I guess in this case, the more you know, the less you know.
Anyone keep their storage and house as an open system and the boiler as a closed system? I would like to do this because I have a 500 gallon plastic tank I want to use and it can't be pressurized. I plan on just using a plate exchanger to transfer the heat form the boiler side to my holding side. Just wondering if maybe this wasn't a good idea?
I guess you could use cheap small plastic tanks too if that was needed and worked better.
I guess you could use cheap small plastic tanks too if that was needed and worked better.
Like damitchell9's original post, I too do not want to use up a ton of space for storage but the longer I surf and lurk here I find it is most-likely a nescessary evil. So here's a most-likely strange idea... would it be possible to bury a large tank outdoors and just plumb it in and out of the house? Do such tanks already exist? I know this sounds crazy to some but I have access to digging equipment and I'd much rather have the storage out of my "useful" area and out of the way...
Crazy?
Crazy?
One thing to consider is if you have multiple smaller tanks in your basement the heat loss from the tanks are actually heating the area in your basement so your heat loss is being used to your benifit.
I'm thinking of adding a storage tank primarily for the heat loss in the area i would be storing the tank.
I'm thinking of adding a storage tank primarily for the heat loss in the area i would be storing the tank.
The pressurized tanks that Bioheat (formerly Tarm USA) sells are 220 gallons each and are ganged up for more total volume.
Pages 3 and 4 on this pdf show a few configurations:
(broken link removed to http://www.woodboilers.com/userfiles/file/Solo) Innova Plumbing.pdf
Whether they are connected in parallel or series, using the largest size pipe you won't be embarrassed by will help to reduce turbulence in the tank and help preserve the stratification. I favor the series hookup connected into the top of the first tank, out the bottom to the top of the next tank, etc.
But I don't know how much if any better it works than parallel. Good arguments either way.
Pages 3 and 4 on this pdf show a few configurations:
(broken link removed to http://www.woodboilers.com/userfiles/file/Solo) Innova Plumbing.pdf
Whether they are connected in parallel or series, using the largest size pipe you won't be embarrassed by will help to reduce turbulence in the tank and help preserve the stratification. I favor the series hookup connected into the top of the first tank, out the bottom to the top of the next tank, etc.
But I don't know how much if any better it works than parallel. Good arguments either way.
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