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| Does a curved dip tube reduce efficiency? | Rate Topic |
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| Posted: Mon Mar 8th, 2010 01:20 pm |
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1st Post |
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Realmacaw Member
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Everything I've read from the owners of this web site has been spot on, great advice. The only exception I've found is they say if you have a water softener you don't need a sediment flush kit. I had an aluminum anode that left 6" of sludge in the bottom of the tank. However, the owners of this site say they don't like aluminum anodes, that aluminum anodes give off 1,000 times more reaction byproduct than magnesium anodes. Even with a water softener, I think a flush kit would have helped a lot. I have not yet tried a curved dip tube sold on this site but it sounds GREAT. I did a quick Google search for curved dip tube. A guy with a new patent for a water heater dip tube claims the mixing creating by most dip tubes, including curved ones, reduces efficiency since it disrupts the thermal layer. In other words, the cold water coming in cools some of the hot water before it leaves the tank. In his patent, he says, "Horizontal or curved dip tubes with unrestricted outflow create a revolving cyclone of turbulence, which ultimately may be worse than the bottom facing tube." He provides NO scientific testing of this claim. Obviously, if sediment builds up, efficiency goes down. He doesn't address that problem. The first link includes his claims and the second link shows a drawing of his dip tube. http://www.faqs.org/patents/app/20080302315 http://www.patentauction.com/patent.php?nb=3542 I am inclined to think his invention is NOT a good idea since it does nothing to remove sediment. Does anyone else have any comments about any inefficiency created by a dip tube that causes turbulence in the water (such as a curved dip tube)?
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| Posted: Mon Mar 8th, 2010 06:59 pm |
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2nd Post |
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scott123 Member 
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Does this this new dip tube increase energy efficiency - meaning that it will take less energy to heat a tank full of water to a final temperature? I am not sure the author is saying that. What he is saying is by reducing the turbulence you will not disturb the thermal barriers and will get the hot water from the top of the tank (the hottest available) - and not get cooler warm water due to the mixing effect when one introduces the cold water to the tank. I suspect this mechanical mixing would not need to be scientifically proven - it does occur. Other than the possibility of using less energy - the question is how bad is it really. Look at a simplified/exaggerated examples: Tank one has heated 40 gallons of water to 120 degrees and you use 20 gallons and blast-mixed in 20 gallons of 50 degree water. If everything mixed you would have a tank of 85 degree water and the water from your heater output would be 85 degrees at that moment. Tank two using the new nozzle - same scenario as above - allows the cold water to stay at the bottom and hot at the top. In a perfect world you would still have 120 degree water available at the top - but if you could draw water fast enough the water at the output would start to drop and then you would have 50 degree water that was at the bottom. You could imagine the 85 degree water would be at the center of the tank - thus allowing you access to the top 20 gallons of water greater than 85 degrees. In both situations if you stopped using water after the initial 20 gallons -- would they both take close to the same amount of energy to heat the whole tank to 120 degrees again? Would the second tank use less energy to get its complete contents to 120? A ME verse in thermal could answer that and I did not see that in the patent application, so the efficiency referred to may not be due to using less energy - but simply allowing the user to have more of the hottest water available to him. The effect of shorter vs tall tanks vs overall size and btu and water input/output temps along with speed of water use would all play a part into how much would this mixing be a problem. But one could see the advantage of the non mixing effect of the new nozzle, but it would be at the cost of sediment agitation.
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| Posted: Mon Mar 8th, 2010 09:45 pm |
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3rd Post |
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Realmacaw Member
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The patent was filed June 8, 2007. Almost 3 years have went by (out of 20 from the date of filing). It appears the patent hasn't been licensed, sold, or manufactured. Most patents are never turned into products. My guess is sediment removal is more important than minimizing disturbing the thermal layers since efficiency will go down if sediment builds up.
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| Posted: Mon Mar 8th, 2010 09:59 pm |
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4th Post |
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Realmacaw Member
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Just because water spins at the bottom from a curved dip tube, does it cause the cold water to rise and mix with the hot water at the top faster? I don't know the physics of cyclones. Most cyclones have a hollow center that is calm. Most water heaters have the center filled with an exhaust pipe. The filled center would create friction on the spinning water. I know if you want to drain a bottle, it is much faster to hold it upside down and spin it and create a cyclone vs. just holding it or shaking it. It's possible the spinning water at the bottom of a water heater from a curved dip tube isn't fast enough to create much rotation at the top.
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| Posted: Tue Mar 9th, 2010 06:30 am |
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5th Post |
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eleent Member
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Hello: This is one of those topics that's filled full of speculation, claims and incomplete info. Dip tubes have been made specifically to mix up water in the tank, claiming better performance. Only side by side testing, done with accuracy will tell if different dip tubes make any difference at all. Still, so much depends on how water is used, both how much and how fast, that the likelihood of a complete scientific answer is slim. My own experience installing thousands of curved dip tubes is people sometimes tell me they can take longer showers. Nobody has complained of less hot water. Yours, Larry
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