How much energy does water heater use when I'm not home?

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illumination
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Re: How much energy does water heater use when I'm not home?

Post by illumination »

I've used the same circuit breaker as a "switch" for something like 15 years that I use to operate some of the features on my pool. I had so many issues with the automation features that I just bypassed it and use the breakers. No issues, and a new circuit breaker is $5 if it ever does wear out. I wouldn't sweat it.

I have a whole "shut down" procedure for my house when I go on vacation, like shutting off the water to my home, cranking the thermostat back, putting the water heater on the vacation setting, etc. It takes just a few minutes, I just hate wasting energy when no one is here even though the actual dollar amount is pretty minimal. In the summer though, not running the AC at a cold temp can actually be pretty substantial, closer to $100 a week.

My guess is a conventional, electric water heater tank being shut off for a 2 weeks is probably something like under $10 in utility savings.
Californiastate
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Re: How much energy does water heater use when I'm not home?

Post by Californiastate »

ariel2 wrote: Mon Jan 24, 2022 2:27 pm
Californiastate wrote: Sat Jan 22, 2022 12:26 pm The OP shuts off their water heater when they go on vacation. The vacations probably cost thousands over a year. The water heater savings might be dozens of dollars over a year. To me it's "The forest for the trees." More money can be saved through other methods.
.....and when added together can be substantial. Turning down thermostats, higher mpg vehicle, doing large loads of laundry and drying clothes on the line, walk to the store instead of driving, washing dishes with cold water, composting instead of transporting kitchen food waste, etc, etc, etc, etc, etc
One can be as frugal as they like. Postulating that taking the bus is the best way to build wealth as you fly to see the Stonehenge solstice is beyond me.
Nicolas
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Re: How much energy does water heater use when I'm not home?

Post by Nicolas »

I wouldn’t think twice about using the CB to turn off my water heater when away. I have a gas heater so I cut the gas instead. But I shut off my well pump at the CB box as well as the main water valve while away for a few days. It’s not enough to just shut the main valve, the well pump must be powered off too. I learned this when my pressure tank burst. The well kept pumping out water as the pressure tank was in front of the valve.
Last edited by Nicolas on Mon Jan 24, 2022 4:50 pm, edited 3 times in total.
H-Town
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Re: How much energy does water heater use when I'm not home?

Post by H-Town »

ariel2 wrote: Mon Jan 24, 2022 2:27 pm
Californiastate wrote: Sat Jan 22, 2022 12:26 pm The OP shuts off their water heater when they go on vacation. The vacations probably cost thousands over a year. The water heater savings might be dozens of dollars over a year. To me it's "The forest for the trees." More money can be saved through other methods.
.....and when added together can be substantial. Turning down thermostats, higher mpg vehicle, doing large loads of laundry and drying clothes on the line, walk to the store instead of driving, washing dishes with cold water, composting instead of transporting kitchen food waste, etc, etc, etc, etc, etc
Put the numbers on the spreadsheet and prove it.

I'd bet for non-boglehead middle class Americans, the majority of their paychecks goes to mortgage, car loans, and student loans. That'll make cutting spending elsewhere like what you mentioned really a moot point.
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hunoraut
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Re: How much energy does water heater use when I'm not home?

Post by hunoraut »

Our water heater uses a non-trivial amount of energy.

When we’re gone for entire month+ at a time, with climate sustem fully off, minimal device drainage, all that is essentially powered in the house is: fridge+freezer+water heater.

They combine 7.5kWh per day or ~250kWh per month or 310watt constantly. The fridge and freezer are essentiallt unused so we assume minimal energy loss.

Hourly power graph shows a perfect spiking every 6 or 7 hours. I assume the fridge is constant and wouldnt draw energy cyclicly like that. I could plug a power meter to each device and eliminate by deduction.
SilverSmurfer
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Re: How much energy does water heater use when I'm not home?

Post by SilverSmurfer »

H-Town wrote: Mon Jan 24, 2022 4:09 pm
ariel2 wrote: Mon Jan 24, 2022 2:27 pm
Californiastate wrote: Sat Jan 22, 2022 12:26 pm The OP shuts off their water heater when they go on vacation. The vacations probably cost thousands over a year. The water heater savings might be dozens of dollars over a year. To me it's "The forest for the trees." More money can be saved through other methods.
.....and when added together can be substantial. Turning down thermostats, higher mpg vehicle, doing large loads of laundry and drying clothes on the line, walk to the store instead of driving, washing dishes with cold water, composting instead of transporting kitchen food waste, etc, etc, etc, etc, etc
Put the numbers on the spreadsheet and prove it.

I'd bet for non-boglehead middle class Americans, the majority of their paychecks goes to mortgage, car loans, and student loans. That'll make cutting spending elsewhere like what you mentioned really a moot point.
By watching our spending - cars, utilities, cell phones and on and on - we easily save hundreds of dollars each month over people who are not aware of their actual spending "costs". I'm also including not watering a lawn, not eating out (or purchasing a shared meal when doing so), etc - not fully apples to apples, but very much easily actionable discretionary spending decisions. They add up, and along with a high savings rate, will allow us to FIRE, while the average consumer works another two decades.

example: viewtopic.php?t=138425
Last edited by SilverSmurfer on Tue Jan 25, 2022 5:46 pm, edited 1 time in total.
barnaclebob
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Re: How much energy does water heater use when I'm not home?

Post by barnaclebob »

mediahound wrote: Fri Jul 18, 2014 4:52 pm Recently, an electrician told me that the circuit breakers are not meant to be used as a switch very often, since they have a limited number of switch on/offs they can do before they go bad. I have no other way of cutting the power to the water heater.
Not a chance that's true. I'd bet a typical circuit breaker can go thousands of cycles before failing.
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mediahound
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Re: How much energy does water heater use when I'm not home?

Post by mediahound »

I really wonder if a water heater uses much electricity to just keep unused water hot? Probably not much.

It seems the vast majority of the electricity it uses, is when hot water is being used in the house.

The times I've gone on a vacation and left the power to the water heater on, my electric bill still went down since no one was using any hot water during that time.

The issue in powering it down when away seems to me is that the water heater then needs to heat the water back up when you turn it back on.
Nicolas
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Re: How much energy does water heater use when I'm not home?

Post by Nicolas »

mediahound wrote: Mon Jan 24, 2022 4:47 pm I really wonder if a water heater uses much electricity to just keep unused water hot? Probably not much.

It seems the vast majority of the electricity it uses, is when hot water is being used in the house.

The times I've gone on a vacation and left the power to the water heater on, my electric bill still went down since no one was using any hot water during that time.

The issue in powering it down when away seems to me is that the water heater then needs to heat the water back up when you turn it back on.
The question then is how long are you away? There comes a point where the savings in not being powered exceeds the cost to reheat upon your return. You’d need research to determine that point. I prefer to err on the side of the power savings accrued from being powered off.
Last edited by Nicolas on Tue Jan 25, 2022 8:31 am, edited 5 times in total.
psteinx
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Re: How much energy does water heater use when I'm not home?

Post by psteinx »

If the hot water heater is using the same heat source, at about the same efficiency, as the house itself, then for the months of the year that the house needs to be kept warm*, the lost heat from an unused water heater doesn't matter much. i.e. Yes, there's thermal loss from the water heater, but that escapes into the surrounding space. Assuming THAT space is within the house's overall thermal envelope, then it reduces the amount of heat that the furnace must provide.

Yeah, there are some assumptions, and it doesn't apply when you're using air conditioning rather than heating, but maybe if you're leaving for 3 weeks in December, you don't have to fuss too much with your natural gas hot water heater, when you also have a natural gas furnace...
Californiastate
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Re: How much energy does water heater use when I'm not home?

Post by Californiastate »

Insulate the hot AND cold water within 5’ of your water heater. I insulated my T&P line for 2’ because it was warm to the touch.
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willthrill81
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Re: How much energy does water heater use when I'm not home?

Post by willthrill81 »

hunoraut wrote: Mon Jan 24, 2022 4:29 pm Our water heater uses a non-trivial amount of energy.

When we’re gone for entire month+ at a time, with climate sustem fully off, minimal device drainage, all that is essentially powered in the house is: fridge+freezer+water heater.

They combine 7.5kWh per day or ~250kWh per month or 310watt constantly. The fridge and freezer are essentiallt unused so we assume minimal energy loss.

Hourly power graph shows a perfect spiking every 6 or 7 hours. I assume the fridge is constant and wouldnt draw energy cyclicly like that. I could plug a power meter to each device and eliminate by deduction.
Much of those 300 watts of continuous power draw is due to the fridge and freezer. Both probably consume an average of about 80-100 watts each, perhaps more if the freezer is an unheated garage and its warm outside. And you likely have some fairly phantom loads too that can add up quickly. It's not unusual for a TV to draw a few dozen watts when turned off. Surge protectors, modems/routers, garage openers, microwaves, ovens, and other items all draw a few watts at least each.
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hunoraut
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Re: How much energy does water heater use when I'm not home?

Post by hunoraut »

willthrill81 wrote: Mon Jan 24, 2022 6:22 pm Much of those 300 watts of continuous power draw is due to the fridge and freezer. Both probably consume an average of about 80-100 watts each, perhaps more if the freezer is an unheated garage and its warm outside. And you likely have some fairly phantom loads too that can add up quickly. It's not unusual for a TV to draw a few dozen watts when turned off. Surge protectors, modems/routers, garage openers, microwaves, ovens, and other items all draw a few watts at least each.
These are hourly bars, with hourly 1000W spikes that average out to 300W continuous across the day.

Image

Freezer is inside, so there shouldn't be extra loss to that. Basically it's a battle of thermal retention between the 3 big devices. And they're just too difficult to access to plug in a meter.
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Re: How much energy does water heater use when I'm not home?

Post by jharkin »

Its always fun in these threads to watch the replies and take bets on how long its going to take for somebody to realize that this was dug up from 8 years ago and the original poster probably forgot they asked by now... ;)
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Re: How much energy does water heater use when I'm not home?

Post by H-Town »

jharkin wrote: Tue Jan 25, 2022 9:34 am Its always fun in these threads to watch the replies and take bets on how long its going to take for somebody to realize that this was dug up from 8 years ago and the original poster probably forgot they asked by now... ;)
OP is still actively engaging in this thread.
Time is the ultimate currency.
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