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Discussion Starter · #1 ·
We have our water heater on a switch and turn it on for a half hour every morning and it's off the rest of the day. My question is this; During the day, as heated water is used from the tank, is an equal amount of cold water entering the tank to replace it at the same time and mixing with the heated water in the tank?
 

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We have our water heater on a switch and turn it on for a half hour every morning and it's off the rest of the day. My question is this; During the day, as heated water is used from the tank, is an equal amount of cold water entering the tank to replace it at the same time and mixing with the heated water in the tank?
Yes

Some people plumb in a tank or old, non-operating water heater before the operating waterheater. That way, room temperature water enters the water heater as opposed to ice cold well water. The room temperature water does not cause the temperature in the water heater to drop as much and requires less energy to heat.
 

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agmantoo
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The water leaving the tank is forced out by cold water entering the tank. The water "layers" in the tank with the hottest in the top and the coldest in the bottom. As the day passes, with the power off, the hotter water will get colder and the colder will get warmer as the tank slowly equalizes and as heat is lost to the outside of the tank and through the plumbing. If I were doing as you are I would disconnect the upper element. The upper element and the lower element are never on at the same time. You would have more stored warm water and the top element would not be coming on as you finish the morning but not turned the switch off since the 30 minutes may have not lapsed. You could experiment with a reduction in time with this arrangement.
 

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Tempering tank is a term used for the tank Cabin Fever described.

You might also benefit from recovering the heat from the waste water and using that to help warm the incoming tank water. http://apps1.eere.energy.gov/consumer/your_home/water_heating/index.cfm/mytopic=13040

It gets mighty cold in Maine but for many months of the year you could use a batch hot water heater, i.e. simply a tank painted black and installed in an enclosed box with clear cover and placed in the sun. That could serve as your tempering tank and instead might provide you with the needed hot water. Better of course would be to make it a cusp reflector unit, shown here about 2/3rds of the way down the page. The tank sits at the apex of two j or u shaped reflectors for maximum solar gain. http://www.dreamgreenhomes.com/plans/sunearth.htm The well respected Rodale Institute developed plans for such unit and give detailed instructions in their older published book, "The Homeowner's Handbook of Solar Water Heating Systems" by Bill Keisling. Many libraries still have it available and copies can also be found via used book sales. I purchased my copy off of Ebay along with a companion book for solar air heating.
 

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Tempering tank is a term used for the tank Cabin Fever described.

You might also benefit from recovering the heat from the waste water and using that to help warm the incoming tank water. http://apps1.eere.energy.gov/consumer/your_home/water_heating/index.cfm/mytopic=13040

It gets mighty cold in Maine but for many months of the year you could use a batch hot water heater, i.e. simply a tank painted black and installed in an enclosed box with clear cover and placed in the sun. That could serve as your tempering tank and instead might provide you with the needed hot water. Better of course would be to make it a cusp reflector unit, shown here about 2/3rds of the way down the page. The tank sits at the apex of two j or u shaped reflectors for maximum solar gain. http://www.dreamgreenhomes.com/plans/sunearth.htm The well respected Rodale Institute developed plans for such unit and give detailed instructions in their older published book, "The Homeowner's Handbook of Solar Water Heating Systems" by Bill Keisling. Many libraries still have it available and copies can also be found via used book sales. I purchased my copy off of Ebay along with a companion book for solar air heating.

Hi,
In addition to the batch heater that Windy talks about, you can build a full four season one like mine for less than $1000:
http://www.builditsolar.com/Experimental/PEXColDHW/Overview.htm


Gary
 

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Discussion Starter · #6 ·
Thanks for the replies, very informative. Right now I'm thinking about a passive solar on the roof feeding an electric in the house. Both twenty gallons, with just the two of us old folks we really don't use a lot of hot water.
 

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Master Of My Domain
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i bet i spent two hours looking over your latest solar collector design, gary. hehe...i would love to build one someday soon.
 
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