Lower your hot water temperatrure

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micky

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Nov 23, 2021, 10:08:55 PM11/23/21
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Just heard some kind of commercial that said to save money, lower the
home thermostat and the hot water temperature.

The first works, but if you lower the hot water temp doesn't that just
mean you'll use less cold water to get the temp you want, whereas now
you're using more cold water and less hot water, even if the hot water
is hotter. IOW, 6 of one, half-dozen of the other.

There would be a savings when the hot water in the pipes, that haven't
reached the faucet when you turn off the spigot, would cool off but
wouldn't waste as much heat when doing that. But that seems very minor
to me.

Rod Speed

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Nov 23, 2021, 10:25:00 PM11/23/21
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micky <NONONO...@fmguy.com> wrote

> Just heard some kind of commercial that said to save money,
> lower the home thermostat and the hot water temperature.

> The first works, but if you lower the hot water temp doesn't that just
> mean you'll use less cold water to get the temp you want, whereas
> now you're using more cold water and less hot water, even if the
> hot water is hotter. IOW, 6 of one, half-dozen of the other.

No, you save the energy used to raise the temperature of the
water in the storage hot water tank or the energy used to heat
the water to a higher temperature in an instant hot water system.

> There would be a savings when the hot water in the pipes,
> that haven't reached the faucet when you turn off the spigot,
> would cool off but wouldn't waste as much heat when doing
> that. But that seems very minor to me.

Yes, that's a minor part of the saving.

Dean Hoffman

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Nov 23, 2021, 10:28:42 PM11/23/21
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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.

danny burstein

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Nov 23, 2021, 10:29:11 PM11/23/21
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In <0tarpg9rrhq128amr...@4ax.com> micky <NONONO...@fmguy.com> writes:

>Just heard some kind of commercial that said to save money, lower the
>home thermostat and the hot water temperature.

>The first works, but if you lower the hot water temp doesn't that just
>mean you'll use less cold water to get the temp you want, whereas now
>you're using more cold water and less hot water, even if the hot water
>is hotter. IOW, 6 of one, half-dozen of the other.

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.


--
_____________________________________________________
Knowledge may be power, but communications is the key
dan...@panix.com
[to foil spammers, my address has been double rot-13 encoded]

Ed Pawlowski

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Nov 23, 2021, 10:33:31 PM11/23/21
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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!

Ed Pawlowski

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Nov 23, 2021, 10:57:26 PM11/23/21
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On 11/23/2021 10:28 PM, Dean Hoffman wrote:

>
> 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.
>

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.

gfre...@aol.com

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Nov 23, 2021, 11:52:23 PM11/23/21
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gfre...@aol.com

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Nov 23, 2021, 11:57:43 PM11/23/21
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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.

Ed Pawlowski

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Nov 24, 2021, 1:15:07 AM11/24/21
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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.

angelica...@yahoo.com

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Nov 24, 2021, 5:40:01 AM11/24/21
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On Tuesday, November 23, 2021 at 11:57:43 PM UTC-5, gfre...@aol.com wrote:

> 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.

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

Dean Hoffman

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Nov 24, 2021, 7:19:10 AM11/24/21
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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.


gfre...@aol.com

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Nov 24, 2021, 10:07:30 AM11/24/21
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The heat is still going into your house.

angelica...@yahoo.com

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Nov 24, 2021, 10:27:08 AM11/24/21
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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

trader_4

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Nov 24, 2021, 11:28:08 AM11/24/21
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On Tuesday, November 23, 2021 at 10:29:11 PM UTC-5, danny burstein wrote:
> In <0tarpg9rrhq128amr...@4ax.com> micky <NONONO...@fmguy.com> writes:
>
> >Just heard some kind of commercial that said to save money, lower the
> >home thermostat and the hot water temperature.
>
> >The first works, but if you lower the hot water temp doesn't that just
> >mean you'll use less cold water to get the temp you want, whereas now
> >you're using more cold water and less hot water, even if the hot water
> >is hotter. IOW, 6 of one, half-dozen of the other.
> 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.

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.


gfre...@aol.com

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Nov 24, 2021, 3:05:56 PM11/24/21
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On Wed, 24 Nov 2021 07:27:03 -0800 (PST), "angelica...@yahoo.com"
Probably true but that is the energy loss we are talking about.

gfre...@aol.com

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Nov 24, 2021, 3:23:52 PM11/24/21
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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.

micky

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Nov 24, 2021, 5:28:44 PM11/24/21
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In alt.home.repair, on Wed, 24 Nov 2021 03:29:05 -0000 (UTC), danny
Okay, you've convinced me. My bad.

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