Does my Behmor need a Variac?

[rgrosz78]

This Behmor thread on Home Barista got me thinking. It says the Behmor was designed assuming the average household only has 116 volts available. But this other H-B thread describes how a Variac improves roasts on a HotTop.

Do I need a Variac? Every year I go through the same hassle. As summer approaches, the air conditioners start running, and sucking away all my voltage.

Only one of the three outlets available for roasting gives a decent amount of power. For June through August, I need to start roasting before 9 AM. Otherwise the very low voltage makes my roasts take about 2 minutes longer - which is WAY too long.

Here is what the available voltage looked like last year:

Code: [Select]

                     Starting  Voltage after
     Date      Time     Voltage     7 minutes
01/01/2011    2:20 PM   121.3       116.5
02/01/2011    9:20 PM   121.3       116.4
03/06/2011    2:07 PM   121.4       117.0
04/04/2011    4:20 PM   120.8       115.6
05/07/2011    2:50 PM   120.5       115.7
06/05/2011    11:30 AM  120.4       114.8
07/17/2011    7:30 AM   121.6       116.7
08/06/2011    10:00 AM  119.7       115.4
09/04/2011    11:20 AM  121.0       116.0
10/07/2011    1:45 PM   121.0       115.8

I have already gone through the drill of decreasing my roast size. For 2012, I typically roast 9 oz and P3, or 10 oz on P1. For 2011, I was roasting 10-11 oz on P3, and 12-13 oz on P1. I did this to shorten my roast times, since many people have commented that I am baking my beans - instead of roasting them.

On 05/06/2012 I roasted 10 ounces of New Classic Espresso beans. It took 20:30 to reach second crack using P3. On 05/23/2012 I roasted 10 ounces of Costa Rica beans. It took 15:30 to reach second crack using P1.

Do I need a Variac? Would this eliminate my never-ending adjustments to control the length of the roast?

[BoldJava]

...
I have heard that a Variac can help, but you want to be careful not to let the voltage swing too high which might possibly damage the electronics in the Behmor.  The voltage dips when the load is applied and the heaters are going full boar, but when the current draw eases up the voltage will come back up too...

I run an old Powerstat variac.  I use the variac when my "under power" voltage is below 118v.  I do not experience the wide band that Chris describes when using the unit. It seems to be controlled by the variac within a band (under power-- around 119 and then when not, around 122).   There are times I don't need the variac; at other times I do. 

If you grab a variac, stay away from the $100 red ones from China on eBay.  Mine was fried (I mean the burning wires fried) at 6 mos.  Gent wanted to replace it under warranty.  No way -- thing is too dangerous.  I just put it to the curb.

The Gene is at 6 years now, on the second mother board, and if I toast it, it will be time to order another one anyway.  It has served me well.

[Richdel]

I was having similar problems with my Gene, longish roasting times.  I asked a neighbor, who is also an electrical engineer/instrument control specialist, whether he had noticed any voltage line drops at his home during the past months.  Long story short, he "lent" me an old Powerstat variac to use to see if that would fix my problems.

Been using it for more then a year.  If he knocks on the door today and asks for it back, I will be on Ebay 5 minutes after that buying another! 

Prior to the variac, I had voltages drop to a low of 115* with the Gene heater on, to low (IMO) to roast without concern I was baking the beans.  I use the variac and Gene configured like this:

Gene ----> Kill-a-watt------>Variac----->outlet

and with the heater "on" (as opposed to cycling), dial the variac until the KAW is reading between 120v - 121v.  I read that today's electronics can handle  swing of +/- 5% voltage.  That makes the range of acceptable voltage 114v-126v.  When the Gene reaches "set temp", and the heater cycles off during this brief period, the KAW sometimes reads 125-128, but this is only for 5-15 seconds at a time.  I guess I could adjust to keep it within range each time the heater "cycles off", but I would look like a mad scientist rotating the variac dial that often during a 10-14 minute roast.

Made a huge positive difference on my roasting.

[BoldJava]

...
Made a huge positive difference on my roasting.

Absolutely.  Here as well.

Not everyone needs to grab a Powerstat. But, if you have voltage swings that leave you short of voltage, it is a gift.  This is the one I have -- it is overkill but does the job (ebay warning):  http://goo.gl/oRwZz

Powerstats on ebay right now that would do the trick that are 'buy it now' for $75.

[rgrosz78]

Absolutely.  Here as well.

Not everyone needs to grab a Powerstat. But, if you have voltage swings that leave you short of voltage, it is a gift.  This is the one I have -- it is overkill but does the job (ebay warning):  http://goo.gl/oRwZz

Powerstats on ebay right now that would do the trick that are 'buy it now' for $75.

I am a software guy - what does it take to satisfy this definition:
"Powerstats on ebay right now that would do the trick"

[rgrosz78]

This is exactly the one B|Java said we should avoid:

If you grab a variac, stay away from the $100 red ones from China on eBay.  Mine was fried (I mean the burning wires fried) at 6 mos.  Gent wanted to replace it under warranty.  No way -- thing is too dangerous.  I just put it to the curb.

[BoldJava]

This is exactly the one B|Java said we should avoid:

If you grab a variac, stay away from the $100 red ones from China on eBay.  Mine was fried (I mean the burning wires fried) at 6 mos.  Gent wanted to replace it under warranty.  No way -- thing is too dangerous.  I just put it to the curb.

Yep.  Mine smoked at less than 5 months service.  Stinky electrical melt-down.

[rgrosz78]

I am a software guy - what does it take to satisfy this definition:
"Powerstats on ebay right now that would do the trick"

I Googled for Powerstat variac on ebay, and got LOTS of choices - from $45 to $500.

[BoldJava]

Milo knows juice and can suggest what capacity is needed to drive a Gene or Behmor.

[farmroast]

Definitely avoid the china made variacs. Huge failure rates.

[rgrosz78]

Now I am not so sure the variac will really do much for me. This is after reading an older CoffeeGeek thread, with LOTS of excellent discussion of the pros and cons.

[foreRB]

rgrosz78,
I bought the one in the jpegs and it lasted 3 months before wisps of smoke. At that point the chance of fire was too great and like others here it went in the trash. I bought a Powerstat on ebay and it works flawlessly. I am using DIY roaster so you might have problems with too much voltage so get feedback on how many amps you need. There's a big difference in price (mine's twenty amps but there's no electronics to damage on my roaster). It cut the time of roasting in half....foreRB

[jimec3]

I say get a variac, a pid, at least two probes in three different styles, and a usb to serial interface.  The standard roaster needs lots of added complications before it is "tuned" properly. The only thing I ended up liking about my Hottop was the on off button....

[rgrosz78]

Not everyone needs to grab a Powerstat. But, if you have voltage swings that leave you short of voltage, it is a gift.  This is the one I have -- it is overkill but does the job (ebay warning):  http://goo.gl/oRwZz

Powerstats on ebay right now that would do the trick that are 'buy it now' for $75.

I purchased a Staco 20 amp variac last week for $200.

I still have some saved searches from ebay. Here is a Staco 15 amp unit for $120. This one has been "rectified" - I have no idea what that means 

Another one! Here is a Powerstat 22 amp unit for $150.