Turning off electric hot water heater when not home?
 

I have heard of people putting a timer on their electric hot water heater so that it shuts off when not in use. I'm not sure how I would go about hooking up a timer to mine, but I could simply flip the breaker when I leave in the mornings. Currently I take 1 shower per day and it's in the mornings. Other than that I almost have no need for hot water.

Has anyone tried this? How long does it take the heater to get back to proper operating temperatures?

They work great and are easy to hook up, or if you are unsure about how to do it you can pay a pro to do it and still get a return on your investment within a year or two.
If they are available for your voltage of water heater I would go with a digital timer so that you can have it come on lets say on every morning from 5am-7am (water stays hot for 3-5 hours after that) then on Friday and Saturday it also comes on in the after noon for an hour so you can shower before any evening weekend plans.

Excellent. I think I could install it myself. I may also install solar attic fan.

I found a problem yesterday...only the A/C is labeled in my breaker box! Everything else is blank. What electrician installs a breaker box and doesn't label 90% of the switches?

What electrician installs a breaker box and doesn't label 90% of the switches?
90% of them, in my experience.

i've been wondering about these timers as well. my wife and i each take a shower at around 5:30 to 6:30 each morning. we don't need hot water again until around 7 pm when we wash dishes. i also sometimes take a shower in the evening since i work either outdoors or in a metal building with no heat/air/insulation all day.

so would one of these timers be cost-effective for me? basically i need hot water 5:30-6:30 am, and around 7-8 pm during the week. would the whole tank re-heating twice a day be more efficient than keeping it on all day/night?

yup, my house doesn't have a single breaker labeled. trial and error with a circuit seeker solved that

that stinks about the boxes. I may turn everything off for the short time I take putting the timer in.

Tony, here is some good info I found today:

http://michaelbluejay.com/electricity/waterheaters.html

specifically these tips:

slightly off-topic

100% of the panels I've installed are labelled.........

I've been to Michael's website, it has a lot of good reading.

I looked in to solar attic (gable) fans. I didn't see savings advantage for my house. They're DC, only move about 700 cfm and cost three times more than an AC fan that'll move 1800 cfm. If you have a small attic space, it might work for you.

Electric water heaters are insulated pretty well, so you probably won't save much by turning it off. 100% of the energy goes into the water as heat (or very nearly so), so the only losses you can save are "standby losses" from heat radiating out of the jacket. Because electric water heaters don't have a flue that tends to cool the water, they usually retain the heat very well.

If you turn it off after it is hot, leave it off for 8 hours and turn it back on, does the element have to come on to heat the water again? If it does, spend your money on insulating the tank, the pipes coming out of the tank, installing a "thermal trap" in the outlet pipe, etc. If the water in the tank is still above room temperature then you haven't lost all of the heat and you won't save much energy by waiting until you come home to turn the elements back on. The intermittent use of the elements during the day will come very, very close to the longer run you need when you turn the elements back on.

thanks for the link! mines 2004 or newer, so looks like i need to just mess with temperature settings.

even if it does retain most of it's heat there is no reason that it needs to come on after you used your hot water for the day, it would be like turning your tea kettle back on after you pour your tea, if you did that, even with a well insulated tea kettle people would say you were kind of dumb, so why have your water heater automatically come on after you've taken a shower and gone to work?

I have yet to hear of someone that hasn't seen a noticeable drop in there electric bill after installing a timer.

Your analogy falls apart in that an electric water heater is more like a thermos than a teapot.

It takes a certain amount of energy to raise the water a degree ... 2.42 watts per gallon. If you have to raise it 10 degrees, it doesn't matter if the heater comes on ten times to raise it one degree, or if it comes on once to raise it ten degrees. You use the same energy to recover the 10 degrees of heat you lost.

If you are getting standby losses through the jacket and save money by turning it off for 8 hours, you should definitely take the other, cheaper measures anyway. No matter when you heat the water, the heat loss is still happening. There's a good chart with formulas and facts at this PDF file link

Here's a quote from another website:

From http://michaelbluejay.com/electricity/waterheaters.html

You pay for electricity by the kWh, so if you are paying .08 per kWh, your monthly savings with a newer heater is only 1.12 per month. A $40 timer has a payback of about 3 years, and much longer if you pay an electrician to put one in ($80 to $120 in my area).

There is a point where turning it off will save money even with a well insulated tank, but that shouldn't be within 8 hours. If your friends are saving money over that short a period of time they still have a great opportunity to save money (and energy) by insulating the tank and pipes.

"The European Guidelines for Control and Prevention of Travel Associated Legionnaires’ Disease recommend that hot water should be stored at 60°C (140 °F) and distributed such that a temperature of at least 50°C and preferably 55°C is achieved within one minute at outlets."

Well somewhere in between, but closer to the teapot. The thermos does not have copper pipes sticking out thru the vacuum jacket.
:D
If you have the parts for free to turn the heater off sitting in your junk boxes, it makes sense to do so. If you have to buy them, then do a payback calculation.

Yep, and in the US, many local codes require water heaters to be set at no more than 120°F (or 125°F). The state of California has a requirement for that temp at all nursing homes, for instance.

Many codes waive the lower temperature if anti-scald mixing valves are used.

Exactly ... which is why the first thing you should do is minimize heat losses! Fixing a dripping hot water faucet will save you more than a timer, as will insulating. But if the timer is free ... then its a no brainer.

I shudder when I see people spend $5,000 for a tankless water heater to save $130 a year on hot water. A lot of energy saving projects are that way, and that's fine if you want to spend the money. But for most of us, we should do the "biggest bang for the buck" stuff first.

Minimize, sure, but with those copper pipes sticking out, there are serious limitations on how much you will be able to reduce the heat loss.. The best you can do is to insulate the inlet all the way to where the water pipe comes into the house, and the insulate the outlet pipe till it goes into a wall.. That is still not very good.

Absolutely agree with you here. But making a timer for water heater should cost very little. I got a lot of fuji relays, 3 pole, 52 amps at 240 volt rated, with 120 volt coils, for free at the scrap yard. How much could they be surplus? Here is a brand new one with reasonable ratings for 13 bucks.
http://search.digikey.com/scripts/Dk...name=PB1007-ND
Add to this a inexpensive programmable electronic lamp timer for $15, to run the relay, a metal box, and its done.

Thermal traps are the order of the day, with insulation extending to the thermal trap. That reduces the radiation losses dramatically. Some heaters incorporate thermal traps into their instructions.

A thermal trap can be thought of as an upside-down sink trap; after exiting the water heater, loop the pipe down below where it exits the water heater by 6 - 12", then back up. Insulate. Heat rises, so the hot water from the tank will only go up into the pipe to the top of the "trap" you just plumbed. Its amazing how much difference you can feel between the portion of the pipe between the high point and the heater and the portion after the high point. You will save more doing this than installing a timer, but as with a timer, the cost gets too high for reasonable payback unless you are doing the work yourself.

That is very clever. Thanks for the info.

cool link :thumbup:

reduce the water temp
 

When I was living alone, I would turn the temperature of the water down in my water heater so that when I took my morning shower, I just had to turn on the hot water faucet. I didn't add any cold water. I could take nice "hot" leisurely shower (up to ten minutes) and the water would stay very comfortable. Also, when washing my hands or shaving, just the hot water faucet would be used. The dishesfrom my electric dish washer came out nice and clean.
The rate of heat transfer increases with the temperature differential. Even is your tank is insulated well, you are going to lose more heat (energy) faster from a tank sitting at 150F in a cold basement 45F then if your tank is set at 115 or 120. I realize that if there are a lot of people taking a series of showers in your home, this method would not be as practical. Also, mine was a natural gas fired heater which I understand recovers faster than electric. Hey, live alone or just the two of you? Give it a try.

Here's another aspect to consider; with a timer installed and set to fire up the WH during lower electric rates, there's an advantage for ya. Instead of 6,7,or 8 of those one degree cycles at daytime rates, you're getting all 10 during the reduced rate.

I have a switch in my pool house; works great. It is only occupied 2~3 days a month.
I just upgraded it from a 2.5 gallon with all of the insulation gone to a new 6 Gallon should work even better (but with increased recoverytime). (both units 1650 watts)

what did you have the tempset at? 120? 115? or lower?

Hey guys, my dad recently tried flipping the breaker for the "hot" water heater, and it works like a charm !

I live in an apartment and the water heater is gas.

Is there anything that I can do to make the water heater operate only when I need it ?
Since it is gas, I cant just flip a breaker.

( Actually, the trick would be getting to the thing, since my apartments have it behind a locked door on my porch. )

Thanks !

What if you turned off your hot water heater and installed very small hot water heaters for each bathroom and the kitchen of your house, and then just heated up the water when you needed it? Water in a tea kettle doesn't take that long to boil, so I figure you could get water up to a decently hot temperature in a minute or so, depending on how much hot water you needed. I hear the Chinese do this, rather than wasting tons of energy with one huge hot water heater that's always on.

That's a great idea - really !
, but it reminds me of this image. The guy that rigged this up didn't put much effort into it ! :D

I censored the image so as not to offend anyone.

http://farm3.static.flickr.com/2546/...5e5f17dd_o.jpg

Haha! Bonus points for putting the coffee machine(?) where it can fall in and electrocute someone if the water's on! :D :thumbup:

It depends a lot on the ambient temp of the house or closet where the heater is located.

The original poster asked if flipping off the breaker in the morning, then resetting it in the evening will save power.... the answer is absolutely YES.

The reason is simply that heat exchange is not linear to the difference of heat. If the water heater is 60 degrees warmer than the house (60* house, 110* water heater), it is losing heat FASTER than if it is only 20 or 30 degrees warmer than the house. So the heater will likely cycle during the day to keep the hot water hot enough.

If turned off, the heater will radiate heat and get cooler... but it cools more slowly as it gets closer to ambient temps. When you turn it back on, nearly 100% of the heat that is produced by the element goes into the water.

The question becomes: is the heat lost during the day enough to bother flipping the breaker? Since flipping the breaker is essentially zero-cost... it makes sense to do it. Unless the extra breaker cycles shorten the life of the breaker. That could negate savings.

If you wake up more than 1/2 hour before your shower(s), the best thing to do might be turn off the heater all day and all night, just turning it on 30-60 minutes before you shower, then turning it right off after the showers.


Or just get an instant-on hot water heater (tankless) and be done.

Why not just get a $20 timer from Home Depot? My Father's been doing this for years, he runs the water heater approximately 1 hour before he gets up for work, and still has hot water when he comes home. Not HOT HOT, but at least enough to wash hands, couple dishes, etc.

Heres another forum post about running a gas water heater on just the pilot light.

that post links to this article which talks about reducing the vent opening to keep more of the pilot light heat in to heat the water.

As for the locked door, you might be able to card the door if it's not a deadbolt. Failing that, since the door probably opens outward, a hammer and screwdriver applied to the hinge pins would do the trick, but be a lot more work.

Can you talk to your landlord about giving you access to the heater to control it, and offer to take responsibility for anything that might go wrong? That might be better than (illegally) breaking and entering a locked space that you aren't leased permission to access.

It is a great idea. I have seen small conventional 120V water heaters for RVs, as well as the common gas fired ones.

Chinese Water Heater? lolz


anyway, my WH has a timer
i have it set to go on at 3x in the day, for no more than 30 min/time
its good enough for 3 people

and if you ever need more, you push the button
(but dont forget to turn it off, or that sucker is on all day)