I went and got a power meter off E bay, it is a very compact little unit that displays Volts, Amps, Watts and Watthours used. To be honest I am a little surprised how nice and compact it is really. Hooking it up was a piece of cake, I just decided to hook it to the main power leads coming in. The lofting fan only uses a few hundred watts and when you are throwing 7 KW at a roast, the difference is negligible really, not to mention the power factor wank with the SSR's firing and that big ass motor spinning up.
I hooked it up to my Artisan 6 roaster. It was pretty simple, just slip an amp ring around one of the leads which is basically a current transformer and hook the other leads up to the power so it can see the volts, and it's done. I just need to put it in a little project box to make it look nicer, and thinking I'll velcro it for the time being to the top before I decide to Dremmel a slot to actually mount it in the lid itself.
As I suspected the dial for KW on the Artisan is not entirely accurate, it would be very hard to really. They control the heat by firing the power into a resistive coil, it's a heating element out of a dryer. Not to mention your incoming voltage can vary a bunch. I cough cough, know someone who works for the power company so have a big hot transformer on my house, I got a solid 245 - 248 volts coming in. Pushing 10KW load I drop my voltage to 242 volts. Not bad. Someone else may only have 230 coming in and loading that hard especially on a 100 amp circuit could drop it to 220. That's almost 1100 watts difference at 50 amps of power being drawn. Anyways.
I did a roast and dialed it in by metered watts instead of looking at the knob and I believe it will allow me to control a roast much better than just going by the knob position. In the mid range to upper range just a tiny tweak can give you 500 watts. At the threshold of crack, you can essentially stall a 5 lb roast right on the verge of crack, and just need 400 watts to push it over into first and run it through to second. This works nicely if you want to hold in an area to develop a flavor. Sometimes as it progresses, you even back down the heat a bit so it doesn't ramp so fast. By being able to see exactly how much heating power you are putting into a roast, you can fine tune and tweak your roast a lot easier instead of just guessing and oops, too much, turn it back down a twiddle.
I did all this today mind you, so this is a very early prototype, I just wanted to see how it would work first before I pretty it up. So far I think it will work pretty good. The power meter is a China wonder so I don't know how long it will hold up, didn't see anything American that was comparable and not 400 dollars so let's see.
Aaron
