I think I need to get a Variac

[mp]

What I read on a few Chinese sites selling variacs is the amps are rated at 100v not at 120v so they fall some 5 amps short of what USA models rate besides lower quality materials as well..
So a 20amp china is maybe something around a 15amp at 120v.. I have been using the 30a china without any issues this summer when my voltage dropped to 113v not roasting.. This is just $10-$20 more than the 15-20 amp models so better safe than sorry..

Thank you for your observation RareBear.

This is very valuable information.

 

[smico]

So is the theory behind that is that if you put on your line and the Kill-a-watt says that you are getting 15 volts, you will keep the 15 volts?

Or does it mean that if your line is supposed to be delivering 20 volts and it is only delivering 15 then it will step it up to 20?

 

I have forgotten how it works long time ago, but constant voltage transformer automatically keeps voltage at 120 V if input is 100V to 140V or so.  I looked them up now, and they were not as widely used as variacs, so they are not available used at low cost.

[rgrosz78]

I got my variac through eBay searches - thanks to everyone's advice in this thread. The nicest thing about a variac - I can roast any time of day or night in the summer, without worrying about low voltage. I am still using it in the winter to produce consistent roasts.

[rasqual]

I've taken to cascading a constant xformer AND a variac. Gives me enough edge to not worry about stalling the loft on enormous roasts (I generally do 10 oz in the popper -- works great after they dry a bit).

Today I was doing a few really small roasts -- about 5 oz. Forgot how to do 'em!

[farmroast]

Heard of way way too many failures of foreign made models. Avoid. Frying variac not cool. With a little effort a nice cond., low wear on sweeper, used  Staco 15 or 22amp can be found for $75-$125.

[rarebear]

What was the amp rating of the import models that often failed?

Where they rated 15 amps at 100v and they where being pushed past there stated limit ?
Can I use a 10 amp Staco at 15 amps and not have it burn up?

[BoldJava]

What was the amp rating of the import models that often failed?

...

Here is the one that went belly up (as in wire insulation melting) within 4 mos on me.  Rated for 20A. Chinese.  http://www.ebay.com/itm/AC-Output-Variable-Transformer-MAX-20A-Metered-Variac-/160932186910?pt=LH_DefaultDomain_0&hash=item25784e4b1e

[mp]

This is the unit that RareBear has and has not had any issues with:



Click on image for listing.

 

[smico]

Dave and Rarebear did experiment that indicates safety factor of the "Red" variac.

1. Dave: Gene - 1200W - Draws 11A @ 110V - Blows 20A "Red" variac - 20/11 = Safety factor 1.8
2. Dave: Hotop - 750 W - Draws 7A @ 110V - Uses 30A "Red" variac - 30/7 = Safety factor 4.3

Assuming that Rarebear runs his variac without sweat, based on those two experiments I would say that safety factor 3 can be used as border line for "Red" variac.

Most probably Hottop could run on 20A "Red" variac, and Gene could run on 30A "Red" variac, but we need more burnt variacs to prove that.

[BoldJava]

...
Most probably Hottop could run on 20A variac, and Gene could run on 30A variac, but we need more burnt variacs to prove that.

My Gene runs on an old Powerstat, 22A.  I snagged it off eBay, thanks for Farm's tip.  It's a champ.

The gent who sold me the Chinese one would not refund the cost.  He wanted to offer an exchange for another one.  No way; landfill.

[rarebear]

20amps I thought would have worked..
Maybe its just the maker but I'll keep my fingers crossed..

The reason I when with the Red China as after searching ebay was
A) I was not finding USA models that stated they were working...
B) They all when from much more than the prices I see here..

[BoldJava]

...
B) They all when from much more than the prices I see here..

I think mine was $120something if memory serves me.

[mp]

...
B) They all when from much more than the prices I see here..

I think mine was $120something if memory serves me.

That is a good price for that unit.

I've been scouring lately and I concur with CareBear ... there are not many around for a good price that are working and meet the 20 plus amp spec that we are looking for.

There are a few @ $300 or more.

 

[BoldJava]

Your safety is worth the difference between $90 and $330.  An electrical appliance that boosts voltage is not a place to get frugal.

[mp]

Your safety is worth the difference between $90 and $330.  An electrical appliance that boosts voltage is not a place to get frugal.

The safety argument is hard to counter.