You are using more energy if you have your electric water heater at 140.
The hotter something is, the faster it loses the heat. So a water heater sitting at 140 degrees is losing heat faster than a water heater at 120 degrees.

You may use less 'hot water' in your shower, but the hot water at 140 degrees costs more than the hot water at 120 degrees, so it is actually costing you more or less the same. For example, you might be using 20% less 'hot water' but that '140 degree hot water' costs you 20% more than your '120 degree hot water'.

Your dishwasher may run longer, but it is only sitting there using it's heater element to heat the water instead of using the hot water heater's element. Both elements are just as efficient, since both are electric.

That's my understanding, at least.

FWIW, I'd tend to agree. A few thoughts: You say you never run out of hot water. Then you are likely heating more water than you need to anyway, so if you're heating excess water to a higher temp, it's going to cost more. Significantly more? I don't know and wouldn't venture a guess.

With a tank heater, once you start drawing water, you refill it with cold water which will drop the temp of the water in the tank. Then the heater has to bring that cold water up to a higher temp.

I'm not an expert on dishwashers, my my thoughts with my limited knowledge would suggest that it's more efficient to let the dishwasher heat the water it needs rather than have the water heater heat it, lose part of it through the water line to the dishwasher and then bring down the water temp in the tank when the water fills in.

If you have the super insulated tank and put a blanket on the tank on top of it, you can cut down on heat loss which translates to cutting down on money loss. You could also set up a timer system to heat at certain times which could result in a savings, depending on your useage and whether your power company has different rate times.

One caution that comes to mind (and you're probably aware) if you have children or elderly, they could get scalded at too high a temp so keeping it at 120 could help in that way.

Unless you have a specific need for the 140° water (for a hot water wash or something) I think I'd stay with the lower temp.

Just a few thoughts to ponder...

The temp that one should keep there tank at depends on useage. A large family using lots of hot water may need it set higher so that, as you say, each user uses less hot water, mixed with cold, per shower so there is enought to go around. A family would want enough hot water to do multiple loads of wash without having to wait between loads for the hot water to return.

Since I live alone, and only use hot water for one shower per day, one dishwasher load per week, and one or two loads of wash per week, I can set it lower to save money because the hot water tank isn't sitting there unused for hours and hours per day, raging at 140 degrees. That is where you lose money - having the 140 degree hot water sitting there unused, while maintained at such a high temp.

Keep it set as low as you can for your needs. As long as you are not running out of hot water when you need it, 120 degrees would be fine and save money.

The only way that I would think of having hot water tank set at 140 degrees is if the family fairly frequently needed to take showers, run the dishwasher, regular washer, etc. at very nearly the same time and found that they ran out of hot water.

I'd make strenuous efforts to rearrange our shedule(s) to shift some of the usage to different times.

For keeping that water tank at 140 degrees for substantial periods (the rest of the time) means that the heater coils must come on much more frequently to maintain it at that heat ...

... which means much more electricity (or gas) usage.

Which would cause my frugal heart great pain!

ole joyful

I just flip mine on for 30 minutes then off before I take a shower. 40 gal elect. Sometimes I forget to flip it on and still have plenty of hot for a shower.

Even well insulated modern water heaters are normally attached to bare copper pipes that will conduct heat. At least two pipes on my water heater remain constantly hot enough to burn your hand on. That's not a small energy loss. Insulating at least the first meter or two of the pipes attached to your water heater is inexpensive and saves a significant amount of energy.

This doesn't really address OP's original question, but two points I'd like to make (as I'm about to purchase a new water heater myself)...

1. If you can swing it, gas water heaters are, apples-to-apples, more efficient than electric heaters. Gas may or may not be an option where you live.

2. Focus less on the new "EF" ratings of water heaters and more on the insulation --- how many inches, and what is the "R" rating? Generally speaking, 2" of insulation with an R16 rating is going to save you some serious bucks on a monthly basis in your utility bills, because as bud_wi said above, you may have up to 140deg water just sitting there "raging"... but if you have R16 insulation, it'll stay at that 140degs a LOT longer before the gas/flame has to kick in to heat it back up again.

Go gas, and put out the extra money ($75-$100 or so for an equiv-sized tank) for the 2" R16 insulation. Better for your monthly bills, better for the environment, and a nice selling point for resale value when you sell your house.

HTH,
Supra92

I also use the heate for 20 minutes and then i wash my utensils and also i take bath...and there is no more usage of electric ...this will save my money..:)

I enjoyed reading this post. My hot water is set 2 notches above vacation. I think its about 100 degrees....warm enough for a shower, but like the above poster, I'm using only hot water...glad to see I'm still saving money!!

Now, I don't understand how the water heater blanket works? My tank doesn't have one, but my tank isn't hot. Its only 1 year old, and maybe doesn't need a blanket??

The water heater blanket is an extra layer of insulation around the tank. Cuts down on heat loss, just like a blanket on your bed does. If your water in the tank is 100° and let's say your air temperature is 75°, then the heat will transfer and lose some. How much depends on how well insulated your tank is to start with. Keeping it that low would lessen the benefit of added insulation, but in the long run, it may still pay off, especially if you get the insulation at the right price. It wouldn't have to be a specially designed "water heater blanket" but could be any type of insulation. They also help on gas water heaters but since they have flames, you must be very careful on installing them.

BTW, don't forget to drain the water occasionally to get rid of the sediment in the bottom of the water heater tank. You'd be amazed what builds up in there in just a few months time! That buildup will take up room in there so you lose quantity of water, can burn out heating elements on electric heaters and make the heater far less efficient. Simply turn off the heater, close off the inlet water supply and take a few pails or hook up a hose to the drain and start draining off water. I do it about 3 pails at a time and keep going until there's no more discolored water and no more sediment coming out. The plumber recommended doing it every 3-6 months. I probably do mine about once a year. Makes a *big* difference though. I saw the amount of sludge that was built up in my old water heater when that broke open. Nearly 2 feet of sediment in the bottom of the tank! Although that was never drained and was probably 25 years old. But when you think about all the stuff that had to heat up before the water would heat, it makes a big difference.

Now for those like my buddy Ol Joyful, this might not make a difference. If I recall, Joyful uses the galvanized washtub with the teakettle on the woodstove, eh OJ? :) Burn buffalo chips in the stove and melt snow for nice soft hair. My only question is whether you wash dishes before or after you take your bath??? :D Could be a good time for a game of "Twister" (Right foot - bowl... Left hand - dinner plate!...) And yes, I suppose keeping your clothes on will wash your clothes at the same time! LOL

Thinking vacation?

If you have an electric heater, flip the switch before you leave, flip it back on again *immediately* on your return (if you expect to need hot water any time soon after, i.e. within 3 - 4 hours, probably). Maybe leave a note taped to a location inside the house where you'll for sure see it immediately when you walk in the door on your return.

If your heater uses gas for fuel ... make sure that you know how to restart on your return, for if you have the gas co. make a service call to re-light ... you'll be a very unhappy (recent) camper!

cynic

That taking a bath in a washtub behind the kitchen range (which, by the way, heated water automatically at nil extra cost, as long as you remembered to keep the reservoir at the back of the stove filled) came at no extra cost for fuel ... was about 60 years ago.

I didn't know hot water on tap till I went to Univ. - which was not unusual, as most other folks didn't, either.

And the fuel came at no immediate cost, as we cut trees whose tops were beginning to die in our woodlot ... but it took several kinds of equipment to cut and haul it and we needed some specialized equipment in addition to some of the equipment that we used for other purposes on the farm. Plus the time to do all of that work. Plus ... this method of developing fuel is not for lazybones - it's a lot of hard work!

There was a cost, though ... if we'd cut the trees down, we would have had more cropland. But Dad liked to have some trees. Later users tapped some of the trees to make maple syrup.

And these days, of course, those trees take on increasing importance. It troubles me, though, that it seems to me that a number of trees along the roadsides are dying. Pollution's killing of trees, though, is evident to us till the trees fall down (or are cut down) ... but the people who die early due to pollution either disappear underground (or are burned up ... which uses more warming plus polluting fuel, by the way).

Dishwasher? What's that?

Sometimes my daughter lends me her dog ... that was her mother's, prior to her recent demise. She's old, and slightly arthritic ... but she loves to wash dishes! She loves sitting by my side and eating cuttings from the beans, cucumber peelings, etc., as well. Plus chews on the lettuce in the garden, occasionally.

Good wishes for finding a way to get into as much hot water as you need ... at as low a cost for fuel, and concommitant pollution and warming factors, as possible.

ole joyful

Folks who have single-lever faucets should be aware when running water that hot water is mixed in unless the lever is set all the way on cold (typically to the right). My grandmother cannot understand this and is often running the faucet at warm (mid-position or thereabouts) for washing hands, produce, filling the coffee maker, rinsing the sink, etc. When I attempt to explain, she says "The water is not hot!" That's true, because the hot flow hasn't yet reached the faucet .. but it's STILL running hot water OUT of the tank.

dadoes,

How about starting before your grandma has run any such water for a while, turn the single lever to fully hot, start it running, and have her put her hand under it, then do so again every five seconds.

No doubt she knows that the hot water comes out of that side, and quite likely she has been aware that when she starts the water running from that side, it isn't hot for a while.

Does she realize that the water that came out at first had been hot, when it came out of the tank, but cooled as it sat in the pipe for a while?

When she wants hot water ... not much choice but to run it, in order to get the hot.

But when she's happy with cold, no sense in running water that was hot and cooled in the pipe ... and leaving more hot water in the pipe ... to cool before she wants hot again.

Anyway, keep at it.

It took about two years for old uncle, who at that point was living alone, to decide that it would be a good idea to carry one of those alert messaging systems that calls help through his phone when he presses a button.

Sometimes it takes a while for a good idea to penetrate aged brains.

And get acted upon.

ole joyful (no spring chicken)

If I'm going to be gone several days, I'll turn the (gas) water heater way down. I don't shut off the pilot light though. Actually, if you have a pilot light it's good to leave it going since it keeps moisture out of the area so things won't rust. You'd have it going anyway so leaving it on isn't an added expense. But I'll turn it down even the day before I leave so I have a shower and days use out of the water in there then turn it up when I get back. If I forget, I'll probably remember relatively quickly.

And I'm like dadoes' grandmother at times... Force of habit has me turning on the "hot" water faucet to wash my hands. Especially during the summer it's warm enough that I don't really need "hot" water, but I'm still taxing the system, costing me a little bit and not getting the benefit. I'm working on overcoming this bad habit. Just turn on the cold for a normal handwashing. During the summer that is. During the winter my digits feel the cold and I've had my hands frozen so many times they're very sensitive to the cold.

BTW, wash your hands frequently folks. Cold and flu season is here and it's one of the best ways to stay healthy! Studies prove that proper and frequent handwashing is more effective at flu prevention than a flu shot. Sneeze into your elbow and enjoy good health during the year.

Stay healthy, frugally!

I don't have a storage tank at all, just my oil burner. I find the shower too cold if anything is running, the dishwasher, clothes washer, even the heating system. I try to time my shower for early morning or late at night. In winter, I'll turn my thermostat down (to 60) before I jump in the shower. If I'm smart, I turn it back up when I'm done or i have to listen to my family complain about the cold house!

We do not heat our water, except when we want a bath. We have an electic shower which obviously only heats actual water used.Water for dishes boiled in kettle or use dishwasher (on a low setting if dishes not too dirty).

Paper is a good insulator - so stock up on "on offer" toilet rolls and store around the hot water tank (if this is practical of course) - a double saving!

Some years ago the city utility came and installed a timer on my electric water heater that had it operate at two a.m., when there was surplus supply in the system.

Plus they put an insulating blanket over the heater that was shaped like it, to add extra insulation to the amount that was between the tank and the metal cover.

Later, another agency took over the heater system, and when they made a service call, removed the timer and were going to remove the insulation, as well ...

... as " ... they didn't offer that service".

On my objection, they left the insulation, which I reinstalled around the tank.

When I called their office to ask why they didn't use such a sensible system ... no satisfactory answer.

I was doing security guard work at a location where they were renovating and were about to throw out the insulation that they put around pipes, so I grabbed some and installed it around my pipes for several feet from the hot water tank, where they were fairly easily accessible.

Still had some left when I moved here and installed some around the pipes here, as well.

I don't like the idea of stacking toilet paper around the tank - too many gaps for the air to circulate. Bette than nothing, I guess ... but not much.

Good wishes for finding all of the hot air that you need ... and only getting into as much hot water as suits you.

ole joyful

With regard to those electricity-provider guys that were removing the timer from my water heater that shifted usage to a time when there was surplus supply ...

... I'd have liked to have asked them how long they thought it might have been since they/their boss had seen a jackass ...

... and suggested that, on their way back to the office, they stop at a store and get a mirror, then on their return ask him/her how long it had been ...

and if s/he said that s/he'd like to see one, hold the mirror up before his/her face.

The trouble is... it's not that boss that sets the rules, they come down from a long way up the responsibility chain.

That's where we need to apply the pressure.

Let's get busy and apply it.

I've just finished my last full week of being 78, folks - so my candle's burning down: I have a limited length of time remaining in which to work on such problems. Even less so while enjoying good health, as well, quite likely.

Enjoy your fruitful, plus happy, I hope, winter week, folks.

ole joyful

"I've just finished my last full week of being 78, folks - so my candle's burning down: I have a limited length of time remaining in which to work on such problems. Even less so while enjoying good health, as well, quite likely.

Well a very happy birthday to you! I hope we see you around many, many more years. I so enjoy your posts and advice.

Well Joyful, hope you have one of those big, long-burning candles, and make it one of those "trick" ones that you can't blow out! :D

Happy Birthday my friend! And many, many more to come!

I was just reading an interesting site about a guy who was heating his water for two people using ONLY the pilot light. In theory it should work. I would think if you put a blanket, or maybe two on the heater, insulated the pipes and the like it could really work. I don't doubt that the guy does it. And when you consider how much heat is given off and usually wasted by a pilot light, it's something to consider.
The poster has his gas water heater set up so that the main burner cannot come on. In his case, the pilot light alone heats all of the water needed by 2 people. He goes a step further, and does not vent the hot water tank to the outside, and actually restricts the water heater flue passage so that less heat is lost by convection through the flue opening. The justification for doing this is that the pilot light alone is no larger than the pilot light on a stove or gas refrigerator, and these are safely run without and outside vent. While I don't see anything wrong with this logic, I'm not sure I would go this far, as it seems to be getting a bit close to the boundaries of safety. But, it is amazing to me that a standing pilot light can supply this much hot water -- it gives some feel for how much energy a pilot light wastes.
(snip)
How much water should you be able to heat with just a pilot light?

If you take 6 therms per month as the an average pilot light energy use:
Energy per day = (6 therms/mo)(100,000 BTU/therm)(1 mo/30 days) = 20,000 BTU/day
20,000 BTU per day is enough to heat about 30 gallons of water from 50F to 110F assuming 75% efficiency **

** The Calculation: If the water needs to be heated from 50F to 110F, then 20,000 BTU would heat:
Water per day = (20000 BTU)(1/(110F-50F) (1 /1 BTU/lb-F) (1 gal/8.3lb) = 40 gals per day at 100% efic
If the efficiency were 75%, it would heat about 30 gallons per day.

Here is a link that might be useful: A Pilot Light Water Heating Strategy

We have a very old hot water heater. It makes a loud sound when the burner comes on, so we're very aware of how often it is using gas. It comes on when someone runs hot water for dishes or a bath, but it also used to come on frequently when nobody was using any hot water. Just to re-heat the tank, which is one of the biggest ways water heaters waste energy.

I put another insulating jacket over the existing insulation and insulated all the pipes attached to it. Although it must still be losing some heat, since then I have never noticed it coming on when nobody has used hot water. It re-heats after we've used some, and it seems to stay hot enough to avoid coming on again until we use some more.

I hadn't considered the energy from the standing pilot before, but with all our extra insulation that might be enough to keep it hot while we're not using it. Either way, it certainly seems to be saving gas, and it re-heats faster too.