On Thu, 5 Feb 2004 05:19:39 +0000 (UTC), someone wrote:
What the heck is the "vacation" setting? Guess its been a while since
I bought a water tank? Didn't know there was such a thing. Is this
just the same as turning it way down? Or turning it to Pilot? Or
couldn't he just turn it off? Do people need a pre-imprinted label to
tell them to do what they always could, or is that actually some kind
of new feature that has characteristics of I don't know what?
Assuming it is *some* kind of temperature reduction, this would only
save $ if the reduced standby loss for the period in question, came to
more than the btus to re-heat the existing hot water that is now being
allowed to cool down. Now for 4 weeks it seems like it gotta be a
savings. For a couple of days it seems pretty marginal if at all.
The thermostat dials on most new water heaters nowadays say
"vacation" at the low end of the dial. I.e., yes, it's the
same as just turning it down all the way.
You save money if the thermostat is turned down for long
enough to allow the water temperature to drop lower than it
would have if the thermostat hadn't been turned down, even
for an instant. Whether you save a *significant amount* of
money is a different question. Four days is probably pushing
it for a decently insulated modern water heater, but it's so
easy to turn the heater down when you leave and up when you
come back, that it's not even worth worrying about where the
break-even point is -- just turn it down!
On Thu, 5 Feb 2004 19:57:27 +0000 (UTC), someone wrote:
No, because that ignores the cost to re-heat the water back up.
Yes, it saves on standby loss, even for an instant, yes the lower the
temp the less the standby loss. But as we both recognize, standby
loss for short periods is not all that great.
Now here is the flip side. Here is an exercize.
You pay to heat a tank full of water from, say, 50 degrees incoming up
to 130 degrees. Then you turn the heater all the way down - heck, off
- it drops to 60 degrees. Then you turn it back on, and heat a full
tank of water from 60 to 130 degrees (maybe you use 1 cup of HW maybe
you don't). Then turn it off again. Then on. Etc. etc. You could
heat the same tank over and over, and whether this is a NET savings
has to do with how much you would have lost in standby over the
period. E.g., was there a long enough stanby period so there is
enough standby savings to offset the re-heating of the water.
Ehh whatever, I wouldn't bother for less than a week, or even 2.
Of course, one factor people don't often think of is "is it winter or
summer?" If it's winter, the "standby loss" actually represents heat
that goes into the house (presuming the heater is in the enclosed heated
home), so it isn't "loss." Maybe it's not the most efficient use of the
engergy, of course...
In the summer, the equation goes the other way and "standby loss"
becomes doubly problematic because not only is that heat lost from the
water, but it adds heat to the house that must be removed via AC...
With the original poster's question, there woulda been three or four days
when the tank was at a lower temp. Lower temp means lower heat loss.
The first several hours (while the tank is cooling down to vacation temp)
there is no gas use beyond the pilot. And reheating it is the same BTU's
that woulda been used anyhow, when the cold water came in.
I suggest that turning it down does save gas, but not very much.
Christopher A. Young
Jesus: The Reason for the Season
In cyclically reheating water to maintain a tempeature, it certainly does
take more gas to maintain a higher temperature in the tank, even thugh the
burner runs at the same heat and BTUs, it runs less often.
If you *don't* turn the heater all the way down, the same energy that
would have been expended to heat it back up from 60 to 130 degrees is
instead expended to keep the water hot.
In fact, as other people have pointed out, *more* would be expended to
keep the water hot, because (a) heat loss is greater when the water is
hotter and (b) a water heater shutting on and off cyclically is less
efficient than one running constantly to heat up cold water.
And incidentally, it takes a long time for hot water in a modern water
heater to get from 130 down to 60 degrees. That is, I suppose, an
argument for not bothering to turn down the heater when on vacation,
but it doesn't change the fact that regardless of how long you are gone
for, you will always save *some* money by turning the heater down; it
just may not be that much.
If you want to save a few more cents you should do the following
before you leave home:
* Turn off / down your water heater before you take your last shower
so you don't heat the water up only to let it cool down while you are
* Unplug all your TVs. They use power even when they are off so you
won't have to wait for the TV to warm up when you turn it on.
* Unplug all your clocks and anything else that has a clock built in
(e.g., microwaves, VCRs, etc.). You won't be there to use them so
* Better yet, throw your main breaker so all power to the house is
off. Sure, all your food will be ruined in your refrigerator and
freezer but think of the pennies you will be saving. (My cousin
actually did this. Several hundred dollars in food were ruined to save
a few cents.)
My point here is that your savings will be minimal if you are only
going to be gone for 4 days by turning down your water heater. If you
plan to be gone for a month it might be worthwhile to turn it down but
you will have to remember to turn it back up when you get home.
If you really want to save money at your water heater install an
insulating jacket around it (available at any hardware store). That
will give you year-round savings.
Another way to save money at your water heater is to only heat the
water hot enough for your needs. It is inefficient to heat water
hotter than you need only to mix it with cold water at the faucet.
Don't turn it down lower than the temperature recommended for your
dishwasher. And it is dangerous to heat the water to the point of
scalding (especially with small children in the house).
PS -- someone mentioned a "water tank" in this thread; is that another
name for a water heater? Interesting terminology; I think of a tank as
something that only stores water, not heat and store it.
Pretty much every water heater on the market nowadays has enough
insulation inside it that adding additional insulation is pointless.
You only need to add insulation if the outside of the heater is warm to
the touch when you put your hand on it. Even then, if it's a gas
heater, you have to be careful when adding the insulation not to block
the area around where the thermostat and pilot light are.
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