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Take a look at this label on this 40 gallon&nbsp;
electric water heater.

00:00:03.659 --> 00:00:05.752
It lists three wattages:

00:00:05.752 --> 00:00:07.968
Upper is 4500W.

00:00:07.968 --> 00:00:10.310
Lower is also 4500W.

00:00:10.310 --> 00:00:12.717
And of&nbsp;course that totals…

00:00:12.717 --> 00:00:14.871
4500 wa - whatt?

00:00:14.871 --> 00:00:16.206
Who wrote this?

00:00:16.206 --> 00:00:17.926
Actually, that’s not a mistake.

00:00:17.926 --> 00:00:22.030
You’ll find&nbsp;similar labels on most conventional electric water heaters.

00:00:22.030 --> 00:00:29.879
Oh and, by the way, that second&nbsp;listed wattage is what it would run at 
if hooked up to a 208V electrical supply rather than&nbsp;240,

00:00:29.879 --> 00:00:33.515
which you’ll usually find in office and large apartment buildings.

00:00:33.515 --> 00:00:38.722
Using Ohm’s law&nbsp;we can determine that this thing’s heating element has a resistance of 12.8 ohms,

00:00:38.722 --> 00:00:44.277
which&nbsp;at 240V would draw 18.75 amps and thus 4500 watts

00:00:44.277 --> 00:00:51.064
but at 208v it would only draw 16.25&nbsp;amps which works out to 3380W.

00:00:51.064 --> 00:00:52.838
Math is fun!

00:00:52.838 --> 00:00:56.891
Anyway, how can those two numbers add up&nbsp;to themselves?

00:00:56.891 --> 00:00:59.972
This label would suggest 2+2 is 2.

00:00:59.972 --> 00:01:03.291
And I’m pretty confident that’s wrong.

00:01:03.291 --> 00:01:10.056
Well,&nbsp;you might have guessed by the labels “upper” and “lower” that there are two separate heating&nbsp;elements in the water heater -

00:01:10.056 --> 00:01:13.620
indeed there are, and they’re both the same power rating.

00:01:13.620 --> 00:01:17.611
The&nbsp;reason for this silly math has to do with the thermostats.

00:01:17.611 --> 00:01:19.629
Yeah, there’s two of those, too.

00:01:19.629 --> 00:01:27.647
But they’re cleverly interlocked in a way that not only prevents them from running at&nbsp;the same time which would overload the electrical supply

00:01:27.647 --> 00:01:32.340
but also makes the operation&nbsp;
of the water heater smarter and more effective.

00:01:32.940 --> 00:01:36.339
A water heater like this is an extremely simple&nbsp;device.

00:01:36.339 --> 00:01:42.797
It’s really just an exceptionally well-insulated cylindrical tank of water
with a few holes in it.

00:01:42.797 --> 00:01:45.607
Up top there are holes to let water in and out.

00:01:45.607 --> 00:01:50.177
Down below is&nbsp;another hole with a spigot to let you flush out the tank periodically,

00:01:50.177 --> 00:01:54.755
and then there are&nbsp;two holes in the sides of the tank under these covers.

00:01:54.755 --> 00:02:00.707
The heating elements stick into the tank&nbsp;and thus into the water through those holes and when power is run through them

00:02:00.707 --> 00:02:02.552
they get real&nbsp;hot.

00:02:02.552 --> 00:02:04.925
This is really just an overgrown kettle.

00:02:04.925 --> 00:02:12.192
Now, there are actually two more holes in the tank,
one of which leads to the temperature/pressure safety valve up top.

00:02:12.192 --> 00:02:17.136
Heating water makes it expand&nbsp;slightly which increases the pressure inside the tank.

00:02:17.136 --> 00:02:19.567
Ordinarily this isn’t a problem.

00:02:19.567 --> 00:02:25.640
The tank may seem like a sealed pressure vessel
but it’s still connected to the rest&nbsp;of your plumbing.

00:02:25.640 --> 00:02:33.907
As the water inside expands, some water will simply move out of the tank by&nbsp;pushing the water in the supply line backwards.

00:02:33.907 --> 00:02:38.700
However, if you have an entirely closed&nbsp;plumbing system with backflow prevention,

00:02:39.360 --> 00:02:45.437
then that won’t be possible so you probably&nbsp;
have an expansion tank installed with your&nbsp;water heater.

00:02:45.437 --> 00:02:47.140
At least I hope so.

00:02:47.140 --> 00:02:54.802
But anyway&nbsp;if for whatever reason pressure starts building up too high in the tank and/or the water&nbsp;inside is getting too hot

00:02:54.802 --> 00:02:59.981
then this valve will pop open, releasing that pressure and&nbsp;
spraying hot water onto the floor,

00:02:59.981 --> 00:03:03.916
and you will have a very bad day but at least&nbsp;the water heater didn’t explode.

00:03:03.916 --> 00:03:05.341
That’s nice.

00:03:05.341 --> 00:03:08.956
And the final hole in the tank is one many people overlook.

00:03:08.956 --> 00:03:15.739
Because the tank is made of steel which, I don’t know if you’ve heard but doesn’t really like to&nbsp;be in prolonged contact with water,

00:03:15.739 --> 00:03:24.528
a sacrificial anode rod often made of&nbsp;aluminum or magnesium pokes down into the water to take the corrosion bullet&nbsp;for the rest of the tank

00:03:24.528 --> 00:03:25.740
and keep it from rusting.

00:03:26.280 --> 00:03:32.047
The top of that rod lives buried underneath the&nbsp;foam insulation
that's underneath this plug,

00:03:32.047 --> 00:03:34.833
and it can actually be replaced!

00:03:34.833 --> 00:03:38.880
If you do that regularly, it can extend&nbsp;the life of your water heater significantly.

00:03:39.480 --> 00:03:42.584
But almost nobody does that,&nbsp;including me.

00:03:42.584 --> 00:03:43.860
Yay laziness!

00:03:44.460 --> 00:03:46.676
But this isn’t a home improvement channel…

00:03:46.676 --> 00:03:52.247
So&nbsp;what's so special about this water heater that’s making me make a video about it?

00:03:52.247 --> 00:03:56.777
Well, earlier I said the&nbsp;thermostats make it smarter and more effective.

00:03:56.777 --> 00:03:58.773
Allow me to explain.

00:03:58.773 --> 00:04:02.522
Notice that even though this&nbsp;is a 40 gallon water heater,

00:04:02.522 --> 00:04:06.963
its rated capacity is somehow 53 gallons.

00:04:06.963 --> 00:04:10.883
Where did it magic 13 extra gallons from?

00:04:10.883 --> 00:04:17.981
Well, I suppose we can let water out of the tank
while also heating incoming water, can’t&nbsp;we?

00:04:17.981 --> 00:04:20.880
Yes, but there’s more to it than just that.

00:04:21.420 --> 00:04:27.034
First, how exactly does the water flow into and&nbsp;out of this tank?

00:04:27.034 --> 00:04:29.170
Both pipes are at the top,

00:04:29.170 --> 00:04:35.846
but the incoming water supply pipe attaches to&nbsp;a dip tube that travels
all the way down to the bottom of the tank -

00:04:35.846 --> 00:04:41.100
meaning cold water enters the&nbsp;tank from below and pushes hot water out the top.

00:04:41.820 --> 00:04:44.875
We can actually observe this with the thermal&nbsp;camera.

00:04:44.875 --> 00:04:50.519
Right now the tank has a fairly uniform temperature,
 just a few degrees above ambient.

00:04:50.519 --> 00:04:54.172
But when I open a tap and start using its hot water,

00:04:54.172 --> 00:04:58.588
we see that it’s only getting colder&nbsp;at the bottom of the tank.

00:04:58.588 --> 00:05:06.004
And here’s something pretty fascinating about water: 
so long as you reduce turbulence and keep things relatively still,

00:05:06.004 --> 00:05:10.448
the hot and cold&nbsp;water inside the tank doesn’t mix.

00:05:10.448 --> 00:05:12.451
Like, at all.

00:05:12.451 --> 00:05:17.858
You can see that as I continue using&nbsp;hot water, the region that’s cold is getting bigger,

00:05:17.858 --> 00:05:22.260
but the hot parts up top are still&nbsp;just as hot as they were when I started.

00:05:22.920 --> 00:05:27.177
This happens because hot water is less dense than&nbsp;cold water,

00:05:27.177 --> 00:05:35.760
so in effect it “floats” to the top of the tank, and as a result a surprisingly sharp&nbsp;boundary between hot and cold is maintained.&nbsp;&nbsp;

00:05:36.480 --> 00:05:42.435
Now you might think that over time that&nbsp;boundary layer will disappear
and the&nbsp;water will mix together but

00:05:42.435 --> 00:05:44.573
for the most part&nbsp;it doesn’t.

00:05:44.573 --> 00:05:51.244
Any water that cools down inside the tank
(like for instance the water clinging&nbsp;to the slightly cooler tank walls)

00:05:51.244 --> 00:05:57.788
becomes more dense and simply sinks to the bottom,
piling in&nbsp;with the rest of the cold water.

00:05:57.788 --> 00:06:04.483
After a very long time without adding heat energy to the tank&nbsp;
the remaining hot water does start to cool down,

00:06:04.483 --> 00:06:07.491
but it takes a lot longer than you’d think.

00:06:07.491 --> 00:06:09.988
Like, the better part of a day.

00:06:09.988 --> 00:06:11.146
It’s pretty wild.

00:06:11.400 --> 00:06:16.423
This thermal stratification
combined with&nbsp;how we fill the tank from the bottom-up

00:06:16.423 --> 00:06:18.731
turns out to be really useful.

00:06:18.731 --> 00:06:24.218
Remember that&nbsp;we have two heating elements
sticking into the tank at two different heights.

00:06:24.218 --> 00:06:32.342
As you continue using hot water, eventually the cold/hot water boundary reaches&nbsp;the bottom heating element and its thermostat,&nbsp;&nbsp;

00:06:32.342 --> 00:06:37.904
kicking that element on so it can start&nbsp;
working to heat the water as it flows into the tank.

00:06:37.904 --> 00:06:43.469
[sound of water trickling in pipes]

00:06:43.469 --> 00:06:47.512
[hissing noise from the element starts]

00:06:47.512 --> 00:06:55.406
Now, 4500 watts may seem like a lot of power,
but in&nbsp;the context of water heating it really isn’t.

00:06:55.406 --> 00:06:59.460
It takes gobs of energy to heat water.

00:06:59.460 --> 00:07:09.150
At most&nbsp;the water heater can put 4500 joules into the water per second, or 1075.5 gram calories per&nbsp;second.

00:07:09.150 --> 00:07:15.312
On a cold winter day the water entering the tank might be 10 degrees Celsius if we’re&nbsp;lucky,

00:07:15.312 --> 00:07:19.890
and our target temperature is generally around 50 degrees Celsius.

00:07:19.890 --> 00:07:23.900
So we need to attain&nbsp;a 40 degree temperature rise.

00:07:23.900 --> 00:07:30.039
If we divide the gram calories we have every second by the 40&nbsp;
degrees we need to increase in temperature,

00:07:30.039 --> 00:07:37.854
we find that we can only heat 26.9 milliliters of&nbsp;
water per second, or about 1.6 liters per minute.

00:07:38.280 --> 00:07:45.199
That’s not too bad, really, but&nbsp;the lowest flow shower heads you’ll&nbsp;generally find here are 1.5 gallons per&nbsp;minute,

00:07:45.199 --> 00:07:47.040
and they may go as high as 2.5.

00:07:47.940 --> 00:07:53.160
Sticking with the smaller number, that’s&nbsp;nearly 5.7 liters per minute of flow.&nbsp;&nbsp;

00:07:53.880 --> 00:07:57.318
Of course most people temper hot water with a&nbsp;bit of cold water

00:07:57.318 --> 00:08:02.055
so we might only have 4 liters leaving the hot water tank every minute

00:08:02.055 --> 00:08:06.335
but that’s&nbsp;still more than double what we can heat with 4500 watts.

00:08:06.335 --> 00:08:09.588
So we’re going to run out of hot water&nbsp;eventually.

00:08:09.588 --> 00:08:11.160
There’s just no getting around that.

00:08:11.700 --> 00:08:15.173
Even if we try and heat the water as it enters the&nbsp;tank,

00:08:15.173 --> 00:08:22.740
the water is simply moving out too quickly and it won’t reach the target temperature by the&nbsp;time we’ve used up the hot water already in it.

00:08:23.460 --> 00:08:28.776
But, remember there’s a second heating element&nbsp;above the one at the bottom.

00:08:28.776 --> 00:08:30.509
It isn’t any more powerful

00:08:30.509 --> 00:08:36.298
but with a bit of&nbsp;strategy we can use it to chase the water as it leaves the tank.

00:08:36.298 --> 00:08:40.113
And that’s exactly what the water&nbsp;heater does.

00:08:40.113 --> 00:08:48.000
With our theoretical 4 liters per minute flow rate, the lower heating element will&nbsp;
only achieve about a 16 degree temperature rise.

00:08:48.540 --> 00:08:52.897
That's nowhere enough, but also that’s not nothing.

00:08:52.897 --> 00:08:55.380
So long as the lower element is turned on,

00:08:55.380 --> 00:09:00.153
in effect the bottom of the tank is filling up with 26 degree&nbsp;water

00:09:00.153 --> 00:09:01.920
rather than 10 degree water.

00:09:02.640 --> 00:09:06.720
And once that tepid water reaches the top&nbsp;element,

00:09:06.720 --> 00:09:12.191
well now its thermostat kicks in and switches the power output to itself.

00:09:12.191 --> 00:09:17.768
We&nbsp;have the same 4500 watts that we did before, but now it’s up here -

00:09:17.768 --> 00:09:21.292
working to heat&nbsp;the water we’ve already started heating.

00:09:21.301 --> 00:09:23.702
[hissy water heater sounds]

00:09:25.458 --> 00:09:27.723
[CLACK, hissing stops]

00:09:29.147 --> 00:09:34.065
[a new and louder hissing begins]

00:09:34.260 --> 00:09:39.734
We can still only achieve a 16 degree temperature&nbsp;
rise with 4 liters per minute of flow,

00:09:39.734 --> 00:09:42.641
but that’ll get us up to 42 degrees.

00:09:42.641 --> 00:09:46.496
Not exactly where we&nbsp;want to be, but still plenty hot.

00:09:46.496 --> 00:09:53.546
We will of course still run out of hot water - once the&nbsp;
top element kicks on the bottom switches off,

00:09:53.546 --> 00:09:59.221
so the water entering the tank is now truly cold&nbsp;and once it’s up near the top...

00:09:59.221 --> 00:10:00.898
well, game over.

00:10:00.898 --> 00:10:04.799
At best we’re getting 26 degree water out of the tank, now.

00:10:04.799 --> 00:10:15.420
But this&nbsp;strategy bought us some extra time with a limited power source simply by changing where we applied&nbsp;that power, and heating the same water twice.

00:10:16.200 --> 00:10:20.260
This is where we magicked 13 extra gallons from.

00:10:20.260 --> 00:10:30.117
4500 watts is 4500 joules per second, and that's 16.2 million joules per hour
or 3.87 million gram calories.

00:10:30.117 --> 00:10:34.620
And lift 96.8 liters of water by 40 degrees celsius.

00:10:35.400 --> 00:10:43.393
So over an hour, this water heater can&nbsp;bring
25.5 gallons of cold water to our&nbsp;target temperature,

00:10:43.393 --> 00:10:46.860
and that is where&nbsp;this “1st hour rating” comes from.

00:10:47.580 --> 00:10:51.637
I reckon it’s only listed as 13 gallons over the&nbsp;true capacity

00:10:51.637 --> 00:10:58.270
since it was calculated using a 208V&nbsp;supply
and assuming we start with freezing&nbsp;cold water.

00:10:58.270 --> 00:11:00.192
Quite conservative.

00:11:00.192 --> 00:11:09.394
In any case, this means that over an hour the energy it can&nbsp;
add to cold water plus the energy it has stored in 40 gallons of already hot water

00:11:09.394 --> 00:11:12.720
is the same&nbsp;as if you had 53 gallons in the first place.

00:11:13.440 --> 00:11:19.380
And on 240V like I have here it&nbsp;may be closer to, like 65 gallons.

00:11:19.380 --> 00:11:27.251
The strategy employed here is frankly genius,
especially considering how simple this&nbsp;device is.

00:11:27.251 --> 00:11:31.076
All we have are two bog-standard&nbsp;thermostats.

00:11:31.076 --> 00:11:38.230
There are no electronics here, there’s no control scheme,
it’s just a thermostat&nbsp;for each heating element.

00:11:38.230 --> 00:11:44.608
The only complication to the circuit design is that the top thermostat&nbsp;always takes priority.

00:11:44.608 --> 00:11:51.163
If that heating element is switched on, the thermostat breaks the circuit&nbsp;to the lower element to prevent it from running.

00:11:51.540 --> 00:11:55.931
Now, you might think this would cause some sort of&nbsp;operational conflict.

00:11:55.931 --> 00:12:01.728
What if we want the bottom thermostat to run
but the top one happens to have kicked on?

00:12:02.537 --> 00:12:04.713
Well, think about this for a sec:

00:12:04.713 --> 00:12:10.881
because hot water stays at the top of the tank naturally, 
and we fill it with cold water comes in at the&nbsp;bottom,

00:12:12.156 --> 00:12:14.732
for the most part that just doesn't happen.

00:12:14.732 --> 00:12:17.559
In fact, top element rarely gets used at all.

00:12:17.559 --> 00:12:22.842
It basically only comes on&nbsp;after you have used up more than half of the water in the tank.

00:12:22.842 --> 00:12:27.865
If you don’t use at least&nbsp;that much, the bottom element will take care of things.

00:12:27.865 --> 00:12:31.260
Same goes for keeping the tank warm&nbsp;between uses.

00:12:31.260 --> 00:12:38.468
And with a low-flow shower head, 15 minutes in the shower is unlikely to&nbsp;use much more than 20 gallons of water.

00:12:38.468 --> 00:12:42.081
So, yeah, the top one just doesn't need to run.

00:12:42.081 --> 00:12:47.045
But if you do happen to use up all the hot water,&nbsp;or even just come close to that,

00:12:47.045 --> 00:12:52.203
well now the strategy of giving the top element priority helps us again.

00:12:52.203 --> 00:12:56.559
While we can of course&nbsp;use the bottom element alone to heat the water,

00:12:56.559 --> 00:13:00.294
after all the hot water it generates down there will float&nbsp;
up to the top,

00:13:00.294 --> 00:13:05.155
doing that means we have to heat the entire volume in one go.

00:13:05.155 --> 00:13:13.380
Whatever&nbsp;hot water it generates at the bottom has to travel through all the cold water on its way&nbsp;up to the top which will of course cool it down.

00:13:14.040 --> 00:13:18.780
Oh, by the way, I should mention that&nbsp;
whenever the elements are actively heating,&nbsp;&nbsp;

00:13:18.780 --> 00:13:26.377
there is some mixing and churning of the&nbsp;water going on inside the tank
thanks to&nbsp;the convection currents that generates.

00:13:26.377 --> 00:13:28.920
You&nbsp;can see that happening here with this kettle.

00:13:29.520 --> 00:13:34.920
That’s how we can heat the entire tank of&nbsp;
water using what amounts to two hot sticks.

00:13:35.520 --> 00:13:41.077
Anyway, if we want to heat 40 gallons&nbsp;
of cold water by 40 degrees celsius,

00:13:41.077 --> 00:13:46.320
it’s gonna take over 6 million&nbsp;calories or about 7039 watt-hours.&nbsp;&nbsp;

00:13:47.040 --> 00:13:52.563
With 4500 watts to play with, that’s gonna&nbsp;take about an hour and a half.

00:13:52.563 --> 00:13:59.640
However, if we only send power to the top element, 
then&nbsp;in effect we only have to heat half of the water.&nbsp;&nbsp;

00:14:00.300 --> 00:14:06.882
We’ll still get some convection currents around&nbsp;the element, 
but we won’t be mixing all of the&nbsp;water together -

00:14:06.882 --> 00:14:09.479
the bottom of the tank will stay&nbsp;cold.

00:14:09.479 --> 00:14:18.771
So we’ll get the water in the top of the tank  (which remember is what leaves first)
up to&nbsp;our desired temperature in half the time.

00:14:18.771 --> 00:14:27.008
So even after completely running out of hot water,
you’ll&nbsp;get truly hot water again after only 45 minutes or so.

00:14:27.008 --> 00:14:33.960
Only once that’s warm and “ready” will we send&nbsp;
power back down to the bottom element to heat up the rest.

00:14:34.620 --> 00:14:38.900
I know that I’m weird, but I think this is amazing!

00:14:38.900 --> 00:14:44.349
I only recently learned that there are two thermostats on the water heater.

00:14:44.349 --> 00:14:50.981
In hindsight it&nbsp;probably should have been a little more obvious since, y’know, there’s two identical covers&nbsp;on the front but

00:14:50.981 --> 00:14:57.120
I just assumed that was for cost cutting or something and thought there&nbsp;
was one thermostat controlling both elements.&nbsp;&nbsp;

00:14:58.200 --> 00:15:02.520
Well, OK I guess there still is,&nbsp;
technically, but… y’know what I mean.

00:15:02.520 --> 00:15:10.869
The simple physics of how hot water behaves in&nbsp;a tank allowed us to implement a very strategic&nbsp;method of heating it

00:15:10.869 --> 00:15:15.660
using nothing but a&nbsp;dip tube and two interlocked thermostats.

00:15:16.518 --> 00:15:20.756
Just doing that covers pretty much all possible concerns:

00:15:20.756 --> 00:15:29.643
how best&nbsp;to heat a cold tank for the fastest-possible hot water, 
how to chase it on its way out&nbsp;for some extra reserve capacity,

00:15:29.643 --> 00:15:35.784
and how to do both those things with a more reasonable amount of&nbsp;input power.

00:15:35.784 --> 00:15:38.280
And that’s what I call … neat!

00:15:40.800 --> 00:15:45.927
You might have noticed that the water heater&nbsp;
is hooked up to some sort of mystery box.

00:15:45.927 --> 00:15:49.855
[CLACK]
What exactly is inside that box is not important for you to know

00:15:49.855 --> 00:15:53.160
but&nbsp;it allows me to disable the water heater at-will.

00:15:54.000 --> 00:15:56.851
Or I guess... selectively enable it.

00:15:56.851 --> 00:16:00.180
The water heater&nbsp;only has power if the red light is on.

00:16:01.020 --> 00:16:04.268
See, I’m in the middle of some experiments.

00:16:04.268 --> 00:16:08.495
Water heaters, as I said, are exceptionally well insulated.

00:16:08.495 --> 00:16:17.505
In fact you would have no&nbsp;idea there’s 40 gallons of piping hot water in there by touching the tank as it feels&nbsp;stone cold.

00:16:17.505 --> 00:16:23.580
The only heat you can really feel is what leaks out of the supply pipes -&nbsp;
I really oughta get some sleeves for those.

00:16:24.240 --> 00:16:30.300
Anyway, because this thing is so well-insulated&nbsp;
that means it’s effectively a battery.&nbsp;&nbsp;

00:16:30.900 --> 00:16:32.993
Remember that math I did earlier?

00:16:32.993 --> 00:16:39.176
It takes over&nbsp;7 kilowatt-hours to heat up 40 gallons of water by 40 degrees C.

00:16:39.176 --> 00:16:41.742
And that’s… a lot!

00:16:41.742 --> 00:16:45.878
Electric&nbsp;water heaters are among the most power-hungry things in your life,

00:16:45.878 --> 00:16:52.092
and the cost to operate them&nbsp;is a big reason
many people chose to use gas instead for water heating.

00:16:52.092 --> 00:16:57.232
I mean, just look at this! Yikes!&nbsp;And those are old numbers!

00:16:57.232 --> 00:17:01.040
Oh and by the way, the reason the cost range is so narrow is because

00:17:01.040 --> 00:17:04.503
energy is energy and water is water.

00:17:04.503 --> 00:17:11.280
Now, I have a time-of-use rate plan with my utility and&nbsp;
power in the middle of the night is quite cheap.

00:17:11.940 --> 00:17:18.900
So for the past couple of months,
I have only been&nbsp;letting this thing operate between 1 and 5 AM.&nbsp;&nbsp;

00:17:19.680 --> 00:17:24.000
And believe it or not, I pretty much can’t tell.

00:17:24.360 --> 00:17:26.813
Now, I can feel the comments already -

00:17:26.813 --> 00:17:33.180
aren’t&nbsp;you supposed to keep your water heater hot at all times? 
Aren’t you the least bit worried&nbsp;about diseases like Legionaries?&nbsp;&nbsp;

00:17:34.380 --> 00:17:43.103
Well, sort of and as a precaution I did set the&nbsp;temperature a fair bit higher before I embarked on&nbsp;this journey...

00:17:43.103 --> 00:17:49.498
but on the other hand for years I have been shutting&nbsp;off the water heater
whenever I leave for more than a day

00:17:49.498 --> 00:17:51.967
and I’m not dead yet!

00:17:52.310 --> 00:17:57.389
But&nbsp;in fairness, that could be a risk and more research is definitely needed there,

00:17:57.389 --> 00:18:02.580
so I am not&nbsp;endorsing this practice. Do not do this at home.

00:18:03.360 --> 00:18:07.060
I can however tell you that when that thing is “charged&nbsp;up”

00:18:07.060 --> 00:18:14.319
it will stay hot for way way wayyy longer than&nbsp;I thought was remotely possible.

00:18:14.319 --> 00:18:23.640
I've taken&nbsp;a shower at 9:00 at night - meaning the water heater had not operated for sixteen hours!&nbsp;- and the water was still scaldingly hot.

00:18:24.240 --> 00:18:27.300
And remember the whole “hot and&nbsp;cold water won’t mix” thing?&nbsp;&nbsp;

00:18:27.840 --> 00:18:30.677
Yeah, you’d think that after a while it&nbsp;would but no!

00:18:30.677 --> 00:18:32.239
It just doesn’t!

00:18:32.239 --> 00:18:36.330
I’ve taken a shower in the morning,
probably using up&nbsp;a good half of the tank’s volume,

00:18:36.330 --> 00:18:42.240
and in the evening - over ten hours later - the water&nbsp;
from the kitchen tap was still too hot to touch.

00:18:42.900 --> 00:18:44.363
More quantitatively,

00:18:44.363 --> 00:18:52.547
I measured the temperature&nbsp;after running approximately 10 gallons of water through the kitchen tap at 132.4 Fahrenheit.

00:18:52.547 --> 00:18:57.933
Five hours later - five hours of the water heater being entirely off -

00:18:57.933 --> 00:19:01.439
the water measured&nbsp;124.3 degrees.

00:19:01.439 --> 00:19:02.880
Just swapped the digits around.

00:19:03.840 --> 00:19:10.560
Somehow, even with at least 10 gallons of cold water&nbsp;
sitting in the bottom of the tank for five hours,&nbsp;&nbsp;

00:19:11.160 --> 00:19:14.542
we lost only 8 degrees of temperature.

00:19:14.542 --> 00:19:18.300
It’s wild&nbsp;but the cold and hot water really just don’t mix.

00:19:19.140 --> 00:19:25.498
Now obviously this strategy won't work for&nbsp;families. 
Good luck spreading 40 gallons a day&nbsp;around.

00:19:25.498 --> 00:19:33.769
But I think it’s worth pointing out that&nbsp;
this thing hardly loses any energy when it’s not getting used.

00:19:33.769 --> 00:19:40.051
And that makes it a really effective&nbsp;energy storage device - and a large one at that!

00:19:40.051 --> 00:19:48.524
This 40 gallon tank stores 70% of the energy that the original&nbsp;
Chevy Volt’s battery pack could!'I hope you can see that there’s a lot of potential for energy management&nbsp;
applications, here. You shut this thing off for an&nbsp;&nbsp;

00:19:48.524 --> 00:19:54.711
I hope you can see that there’s a lot of potential
for energy management&nbsp;applications, here.

00:19:54.711 --> 00:19:59.933
If you need to shut this off for an hour or even two, you you won’t even notice.

00:19:59.933 --> 00:20:04.306
And,&nbsp;what if you put a thermostatic mixing valve on its output?

00:20:04.306 --> 00:20:11.677
Then, you could charge up a more sophisticated&nbsp;water heater well beyond your target temperature when energy is cheap and abundant,

00:20:11.677 --> 00:20:17.225
not&nbsp;only storing that energy for later, but also extending the tank's capacity.

00:20:17.225 --> 00:20:21.840
As a matter of fact that idea is already&nbsp;
in use with some heat pump water heaters today.

00:20:22.560 --> 00:20:28.252
I’ll be keeping track of energy costs here and&nbsp;
will report on how this experiment continues to&nbsp;go.

00:20:28.252 --> 00:20:33.550
I’ll probably do that on my second&nbsp;channel
so you might want to subscribe if you haven’t already.

00:20:33.550 --> 00:20:42.780
But I can already&nbsp;say with complete confidence that a conventional, tanked water heater can be an important&nbsp;part of an energy-management strategy.&nbsp;&nbsp;

00:20:43.860 --> 00:20:47.157
People keep asking for my thoughts on tankless&nbsp;water heaters

00:20:47.157 --> 00:20:54.000
and frankly this experiment is reinforcing my previously-held belief
that they’re&nbsp;not the be-all-end-all.

00:20:54.000 --> 00:20:59.554
They need tremendous amounts of power and can’t store energy for later.

00:20:59.554 --> 00:21:01.800
Plus they have unique maintenance considerations.

00:21:02.580 --> 00:21:06.360
I really think they only make sense&nbsp;
when you have severe space constraints,&nbsp;&nbsp;

00:21:06.360 --> 00:21:13.684
and personally... I gotta say that
if you feel&nbsp;you need the “endless” hot water they can&nbsp;provide,

00:21:13.684 --> 00:21:17.789
it might be worth considering adjusting&nbsp;your routines.

00:21:17.789 --> 00:21:20.280
But that’s just, like, my opinion.

00:21:20.820 --> 00:21:27.483
Anyway, that whole section was basically a&nbsp;
teaser for my next video which will be on&nbsp;home electrification.

00:21:27.483 --> 00:21:30.885
That’s coming soon. At&nbsp;least I hope.

00:21:30.885 --> 00:21:34.741
For now, I hope what I’ve said here will get some gears turning.

00:21:34.741 --> 00:21:43.768
Many of&nbsp;the obstacles we think are insurmountable are in fact a piece of cake with just  a bit of strategy&nbsp;and a dash of management.

00:21:43.768 --> 00:21:45.411
Thanks for watching.

00:21:46.318 --> 00:21:48.790
♫ scaldingly smooth jazz ♫

00:21:50.468 --> 00:21:54.687
You’ll find similar labels on most conventional&nbsp;electric water heaters.

00:21:54.687 --> 00:21:59.867
Oh and, by the way, that second listed wattage is&nbsp;
what would blet deh buh dih be deh

00:21:59.867 --> 00:22:03.268
And by the way, that second listed wattage is what it&nbsp;
would run at -

00:22:03.268 --> 00:22:05.568
what the heck was that noise?

00:22:07.740 --> 00:22:09.120
I heard a weird noise.&nbsp;

00:22:09.900 --> 00:22:13.516
Right now, the tank has a prettyform&nbsp;out… prettyform?

00:22:13.516 --> 00:22:15.291
It's pretty uniform.

00:22:15.291 --> 00:22:18.614
Same goes for keeping the tank&nbsp;warm between uses.

00:22:18.614 --> 00:22:23.034
And a low-flow shower head fit… oh.

00:22:23.034 --> 00:22:24.421
I skipped a word!

00:22:24.421 --> 00:22:30.597
...combined with how we fill the tank from the bottom up turns out to be really useful.

00:22:30.597 --> 00:22:33.197
Remember&nbsp;that we have two heating elemen…

00:22:33.197 --> 00:22:34.648
[belches]
I GOTTA BURP

00:22:35.947 --> 00:22:38.520
Explaining how your water heater works can be a tankless job.

00:22:38.520 --> 00:22:42.355
OK, that's not mine, plenty of plumbing companies the world over use that one.

00:22:42.355 --> 00:22:45.622
Besides, like I said I don't exactly have an affinity for tankless water heaters.

00:22:45.622 --> 00:22:48.203
Especially since electric ones need, like 10 kW just to provide one shower.

00:22:48.203 --> 00:22:50.375
Then you might as well get one of those electric shower thingies.

00:22:50.375 --> 00:22:51.370
Anyway, toodles.

