HomeRoast Digest


Topic: Electrical question on coffee brewers (10 msgs / 298 lines)
1) From: Dennis Guyer
I hope I can explain my situation properly.  I have a drip coffee brewer th=
at is advertised and being able to heat the water to 195 - 205.  It i=
s also listed as using 1400 watts.  Using my Kill a Watt meter, it reads so=
mewhere between 1200 and 1250 watts draw.  My line voltage is usually 118v =
to 120v dropping it around 116v during the brewing process.  The water usin=
g a K-Probe is reading 185 for most of the cycle ending at a high of 193=
.  My question is - is the brewer defective?  Is the line voltage determ=
ining the low readings?  Do I take the brewer back and demand my money back=
 or is this to be expected?
 =
Dennis
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2) From: Allon Stern
On Oct 5, 2010, at 2:17 PM, Dennis Guyer wrote:
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that is advertised and being able to heat the water to 195 - 205.  It=
 is also listed as using 1400 watts.  Using my Kill a Watt meter, it reads =
somewhere between 1200 and 1250 watts draw.  My line voltage is usually 118=
v to 120v dropping it around 116v during the brewing process.  The water us=
ing a K-Probe is reading 185 for most of the cycle ending at a high of 1=
93.  My question is - is the brewer defective?  Is the line voltage dete=
rmining the low readings?  Do I take the brewer back and demand my money ba=
ck or is this to be expected?
The drop in line voltage will affect the temperature that you can get.
Try it under more ideal circumstances - try an outlet that is not shared wi=
th any other circuits that is as close to your breaker panel as you can get=
, and see if your voltage doesn't sag, and the temp readings are better.
Or if you have a studly enough variac, you can boost the voltage to 120V to=
 compensate for the drop in your wiring.
You might try preheating the water to compensate, or insulating the interna=
l tubing if it runs through the reservoir.
Which brewer is this?
-
allon
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3) From: Rich
E=IR  E is the independent variable
P=EIcos(PF)  PF=Power Factor angle.  Assume that the angle is ) and the =
cos=1
Your problem is the 116v....
Look on the brewer label and check what the rated voltage is.  That is =
the voltage REQUIRED to consume 1400 watts of power.
Dennis Guyer wrote:
<Snip>
that is advertised and being able to heat the water to 195 - 205.  It=
 is also listed as using 1400 watts.  Using my Kill a Watt meter, it reads =
somewhere between 1200 and 1250 watts draw.  My line voltage is usually 118=
v to 120v dropping it around 116v during the brewing process.  The water us=
ing a K-Probe is reading 185 for most of the cycle ending at a high of 1=
93.  My question is - is the brewer defective?  Is the line voltage dete=
rmining the low readings?  Do I take the brewer back and demand my money ba=
ck or is this to be expected?
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ariascoffee.com
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ee.com/gallery/main.php?g2_itemId=7820
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4) From: raymanowen
"Your problem is the 116v...."
Exactly.
And the softness or drop in the voltage from the 120v - 125v ac of the
transformer secondary to 116v is mostly due to the resistance in the
overhead steel Neutral line between the power pole and your house. Too much
ohmage.
The steel cable is pretty strong and supports the two weighty soft copper
wires over the span from the pole to the roof jack on the house.
Electrically, the steel cable is more like a rubber band.
If the angle is ), Cos ) =1. Arc Cos 1 = ) - the classic Underwood
Syndrome.
Cheers, Mabuhay, Prost, bitte reichen Sie die Kaffeekanne -RayO, aka Opa!
Got Grinder?
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5) From: Rich
I noticed the attack of the Underwood syndrome right after posting.  No 
edit button....
raymanowen wrote:
<Snip>
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6) From: Dennis Guyer
Thanks to all who responded to my brew temperature question.  The set up we 
have for making coffee prohibits me from changing the location of the coffee 
pot.  Bummer.  However, the power substation near my house (about one mile) 
is being re-built and we are now being supplied by a temporary substation 
about three miles from our location.  Would this have any effect and will it 
get better when the new substation is on-line?
The question of what coffee brewer am I using is the Krups "Power Brew" 12 
cup model.  I think it is only available from William Sonoma stores.  My 
best coffee is using the Aeropress.  But when more volume is needed I need 
to resort to the Krups.
Thanks,
Dennis
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7) From: miKe mcKoffee
All electrical theory aside, heating the water to a specified temperature is
not the same thing as dispensing the same water temperature to the grinds so
likely not defective or technically false advertising. For example one might
PID a Silvia brew boiler, but an offset must be set to compensate for the
lower temperature at the group. The PID then "displays" the brew temp, not
the actual higher boiler temp. Same principle for a dripper, there will be
heat loss from the maximum heated water temp...
Slave to the Bean  miKe mcKoffee
www.CompassCoffeeRoasting.com
URL to Rosto mods, FrankenFormer, some recipes etc:http://www.mckoffee.com/Ultimately the quest for Koffee Nirvana is a solitary path. To know I must
first not know. And in knowing know I know not. Each Personal enlightenment
found exploring the many divergent foot steps of Those who have gone before.
Sweet Maria's List - Searchable Archiveshttp://themeyers.org/HomeRoast/=
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8) From: raymanowen
The new power substation is being installed to solve some other problem.
They're not free, and it probably won't solve your problem.
Have you made note of the times of day during which the power at the outlet
is high and low? Or the total resistance of the wires and electrical devices
between the pole transformer and your coffee pot? The latter will not be
affected by a substation, if you even lived next door to Hoover Dam, and you
can't measure it directly.
Of course, the line resistance between the pole transformer and your roof
jack is not your responsibility. If it's excessive, Reddi Kilowatt should
make it good.
Simple to determine the outside line resistance, exclusive of your circuit
breaker and wiring devices:
   1. With your coffee pot unplugged and no other heavy load on that
   circuit, measure the voltage at a test receptacle on a different unloaded
   circuit in the house-
   2. Record the volts at the test receptacle (V1)
   3. Fill pot with dummy load of water, turn it On, plug it in and record
   (V2} at the test receptacle.
   4. Calculate the voltage difference (V1 - V2) caused by the coffee pot's
   current draw-
   5. Divide (V1 - V2) by the nameplate current draw of the coffee pot. For
   reasons stated by miKe, it won't be precisely accurate but you'll know the
   magnitude of the line resistance. ex: 1225w/117.5v = 10.4 ampere
For example, suppose you see a 119v - 116v = 3-volt change (rise or fall)
between the coffee pot connected and disconnected, measuring at the test
receptacle, and the current is stated to be 10 amperes, but you question
that number and the fraud Kill-a-Watt that gives derived numbers as if they
were basic quantities. Good attitude.
Besides, the 3-volt change on the 117.5-volt median is 2.5% change- Not
interesting to Reddy Kilowatt. They might offer some left-over office party
cheese to go with your whine.
Cheers, Mabuhay, Iechyd da -RayO, aka Opa!
Numbers at night is not good- likely to be misteaks
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9) From: Alchemist John
I'm with Mike here.  There are just too many =
other factors that affect the delivered water =
temperature.  If it is configured as most brewers =
out there, it is heating the water to boiling, =
then 'shooting' it through the cold water =
chamber, cooling it to 195-205.  Overall, I would =
say it has nothing to do with electrical so much as design and thermostat.
At 10:59 PM 10/6/2010, you wrote:
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riascoffee.com
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10) From: raymanowen
Agreed again, but my personal experience with many different machines is
that they operate best with a "hard" power supply, right in the middle of
the nameplate voltage range.
Any thermostat or temperature controller [even PID] would seem to obviate
the need for power supply stability. But when it calls for heating power
that's not there, don't blame an ill design. Besides, the power and heating
ability changes exponentially with the voltage excursions.
Nothing worse than a frustrated PID that calls for the quick shot of heat
and gets almost nothing. PID's work best when there is massively excess
heating power. No controller can generate the needed heat by itself- they
just chop up and discard the excess. Sags and brownouts can be lived
without. The home appliance can be ruined by them.
Cheers, Mabuhay, Iechyd da -RayO, aka Opa!
This message sent from a Dell work station in a commodious Hosptal room I'm
visiting
On Thu, Oct 7, 2010 at 6:45 AM, Alchemist John w=
rote:
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mariascoffee.com
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ariascoffee.com
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-- =
Persist in old ways; expect new results - suborn Insanity...
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