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I have a question about heating water.  RSS feed

 
malcom st. peter
Posts: 13
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Most of the hot water heaters that I see being made with the rocket stove have the water being fed to them from the bottom of a storage tank. My question is what if you took the water to be heated from about 5 inches from the top of the tank, (this water should be at least 1 degree warmer than the bottom) heat that and run the return into the bottom of the tank heating the water in the tank from the bottom up? Thank you for your time.
 
Balint Bartuszek
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Location: Hungary
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If you circulate the water slowly, you have warm water quickly. Since warm water remains on top of the cold, you can have your shower before you heat the whole volume up to comfortable temperature. (The water tanks have their outlet from the top.)

This is best if you circulate the water real gently, for example when thermo-siphon circulation is used.
 
malcom st. peter
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I am thinking more along the lines of thermal storage. My way of thinking is if you take a volume of water and try to heat it would it make more sense to heat continually or do it in stages. The way I see it is if you heat water off the top it is going to be warmer than off the bottom. Adding hot water to the bottom of the tank will with out a doubt heat the water above it, in doing so you are going to raise the temp of the water going into the heating part of the system quicker than trying to do it in stages bye drawing water off the bottom of the tank and adding to the top. In a regular water heater cold water is added to the bottom of the tank doing so keeps the hot water up top, doing this allows you to remove water from the top of the tank with out much temp drop from adding cold water. This is just my observation of how it works, if it works another way please let me know.
 
Balint Bartuszek
Posts: 56
Location: Hungary
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The bottom drawn system will gain a tiny bit more energy, since it will always have colder input in the heat exchanger, so a slightly bigger thermal difference, which aids heat transfer. (if all else is equal)

I think the most efficient method is to draw from the bottom, and always put the water in to the hight which has the same temperature as the input. There are many fancy heat storage tanks on the market, that do something similar, but they are mostly used in systems with different heat input levels. Like you have a natural gas heater and solar collectors heating the same tank. The solar collector will draw from the bottom, and put hot water in the middle. (as it is likely just warm most of the time) While the gas heater will put hot water to the top side of the tank.
 
malcom st. peter
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I c what you are saying and thank you for your input. From what you have explained to me I have made the best decision that I think will work the best with the least amount of headache. Cold water off the bottom and hot water in on the top. Thank you again for your input.
 
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