Lower your hot water temperatrure

Keeping the water unnecessarily hot in the water heater is probably where the losses are. On demand water heaters save energy by heating water only when it needs to be heated.

Assuming (yeh, we know...) this is a standard 40 or so gallon standing water heater where the flame or electric element heats the water, etc., yes, there's a small but sometimes useful savings.

Keep in mind the water in the tank is hotter than the air around it, so is (term used a bit, but not too loosely) trying to escape from the tank and into the basment air.

The heat flow rate is, to some extent, dependent on the difference in temperature between the two sides of the heater wall.

(numbers totally made up for illustratin):

If the basement is 60 degrees F and the tank is also at 60F, then it takes _no_ energy to keep the water at that temperature.

If the water is at 80F, it might take (again, numbers made up), the equivalent of a steady 20 watts to keep the water at 80F

If at 100F, perhaps 40 watts.

If at 110F, make that 60 watts

If at 125F, make that 100 watts.

Which adds up over the month.

Again, two points: My numbers are made up, but not way too off (depending on insulation, etc.)

and b: this is _separate_ from the energy needed to heat the water up, which is, as you noted, mostly a wash (I see what I did there) becuse you'd be adjusting the flow rate and mixing of cold/hot when taking your shower.

Many households have a 40 to 50 gallon tank they are keeping hot. Physics will always move some heat out no matter how well insulated. You lose energy faster at 160 than 120.

I've seen numbers from 4% to 20%. One article said lowering the water temp could save $450 a year. I use gas for hot water, dryer, cooking, grilling. Since I only spend about $180 a year on gas, they would be sending me a check!

How do you like them?

My friend has one at her vacation home. I spend a week or two with her about 4 times a year and I'm not crazy about it. If you want minimal water the flow, of course, drops and it stops heating. In the shower it can be touchy too and you suddenly have cold water if you don't want it too hot.

Some of this may be correctable but not my house so I've not played with it. Nor can I justify the cost based on my gas use. For her, makes since as it is often unoccupied for weeks at a time.

If you have the water heater in the house and the heat is running, the losses are minimal since the heat from the water heater is taking some load off the furnace. If the A/C is on, that waste heat is hitting you twice, once coming in and once going out as A/C load. Since my AC is on a about 6 months a year and the heat is only on a few hours a year, my water heater is outside. For most of the year the first 80-90 degrees are free.

Mine is in the garage so does no affect the AC. Most times for a quick hand washing I just use the "cold" water that is not all that cold.

Only time I hear the water heater kick on is for a shower or sometimes the dishwasher.

Very minimal in my case, since the water heater is in the basement, as are most water heaters in places where the ground freezes.

Cindy Hamilton

I like mine. I need hot water just for me taking a shower or for the dishwasher. One issue was the size of the incoming natural gas line. It limited the size of water heater I could put in. Things worked out ok since I don't need hot water for more than one thing at a time.

The heat is still going into your house.

Sure. Most of it is absorbed by the concrete block foundation, subfloor, etc. I doubt my HVAC system even "notices" it. Especially when compared to the big TV, two computers, refrigerator, and two human bodies.

Cindy Hamilton

It's not only dependent, it's directly proportional to the temperature delta. Water at 140F with 55F ambient, 85 delta is going to lose heat percent faster than water at 130F. to lose heat at about 12% faster than water at 130F. That tanks is sitting there 24/7.

Probably true but that is the energy loss we are talking about.

The reality is, most of the heat in hot water is wasted anyway. It goes down the drain, up the bathroom exhaust vent or it is released into the home. If energy was more expensive we might start heat exchanging those exits. National Geographic in Germantown actually does that in their building. It was built to be energy efficient before that was cool. They heat exchange everything and use the lake out front as storage when there is excess energy captured. It all but the coldest days "the heat" never comes on. It is all recaptured heat from the lights, equipment and people in the building. The lake never freezes either.

Okay, you've convinced me. My bad.

I'm glad they're not putting out falsehoods on the radio. At least not this time.