So ... any actual measurements of how much energy was actually saved? Neat hacking for sure, but it seems somewhere along the line thinking clearly about the goal of "saving energy" got lost in the details.<p>Although I'm not exactly experienced in the field, I'm going to guess it's quite unlikely the water heater's energy consumption was reduced by anything close to 2/3, or even by a significant amount.<p>Most obviously, the author completely overlooked that there are two types of energy use by a tank-style water heater:<p>1) Heating incoming water to the desired temperature.<p>2) Holding the tank at the desired temperature.<p>This setup does nothing to address the first energy need, which is the larger of the two.<p>And, unless the timing is spot-on, it will heat a tank which is not immediately used -- which then cools off, and finally needs reheating later.<p>If you make the (incorrect) simplifying assumptions that (a) a tank loses energy at the same rate regardless of its current temperature, and (b) the burner is instant-on/off to full efficiency, then my pre-coffee mind arrives at the conclusion that reheating a stale tank to a target temperature would use exactly the same energy input as holding it at the target temperature the whole time anyway.<p>Without those simplifications, it still seems likely that the 'stale tank re-heat' will use a decently large fraction of (2)'s energy.<p>tldr; To take large chunks out of your consumption of heating energy, insulate your home better instead. Bonus: It saves you cooling energy during the summer, too!
I've read that turning down the temperature in the tank can increase the risk of Legionnaires disease. I don't know how much of a risk that actually is, though: <a href="http://www.treehugger.com/files/2009/03/turning-down-water-heater-safe.php" rel="nofollow">http://www.treehugger.com/files/2009/03/turning-down-water-h...</a>
This is really interesting. I'm assuming this fine gentleman (or lady folk) reads this thread. Dude, you should totally post back in a month or two and report your actual energy savings.<p>I'm wondering if it's actually inefficient to turn the setting lower and actually heat the water back up later. Does anyone know?
Neat hack, but here is a timer for hot water heaters on Amazon: <a href="http://www.amazon.com/Intermatic-WH21-Electric-Water-Heater/dp/B00002N5FP/" rel="nofollow">http://www.amazon.com/Intermatic-WH21-Electric-Water-Heater/...</a><p>Anyone considering this should also invest in some insulation as others have said.