Couple of dual element questions

[DaWiz]

I am planning on doing the dual element mod and have a couple of questions.

1. Is there any reason why I cannor just "daisy chain" the second element off of the original element?  It seems that it would be easier to add wire from the first element to the second.  If he concern would be the original wire carying the increased current, I have plenty of high temp wire and could replace the original wire.

2. Does anyone know what the amp rating is for the hermal cutoff?  I figure the 1000 watts would be about 8.33 amps.

Glenn

[rexster]

That's what I did. About 1 1/2 inches of high temp wire terminated with ring terminals, from the original connections on each end to the new element. Works great. Can't help you with the thermal cutoff, but I haven't had any problem with mine.

[GusRobin]

As stated it can be done. I took the extra time to do them independently and with an on/off switch so that I can control them individually if needed. Glad I did in that I had to do that when I ran into a PID problem. How often will that happen? probably not much if at all. But for the small amount of work (extra cost was minimal) it was worth it to me.

[DaWiz]

Thanks for the responses.  Cost was not a concern - I have 25 feet of high remp wire and the second element. 

I just want to keep the cabinet modifications to a minimum.  I am trying do decide where to mount the Auber probe permantly in ther cabinet.  I am thinking center of the back wall just below the 3rd rack from the top.  I spent the better part of a day masuring temperature differences in the cabinet and that seems like the best location. 

As a side note I discovered that the Auber temp was off and had to program an offset to get it to read correctly.  I used 3 thermometers and a contained of ice water to check readings.  The Auber was high by 16 F the other 2 were within 1 degree.  Initially I thought it was the probe but using  a second probe the Auber was still 16 F high.  I will probably send the unit in for recalibration before the warranty expires.

[GusRobin]

I would not mount the probe in a permanent location.  You usually want to take the temp at the bottom of the lowest rack. Can't always do that when mounted permanently. I also found that is sometimes would get in the way when I put a lot of meat in the smoker. I ended up plugging the mounting hole and hanging the probe. Then when I upgraded to the dual PID I bought a hanging probe.

[DaWiz]

If I just hang the probe through the vent, it interferes with adjusting the vent.  Also if he smoker has mulyple trays the meat makes hanging it a bit problematic. 

I would suspect that measuring below the bottom rack would be too close to the element(s) - the heat enerated would not have spread out yet.  I will have to measure at that point and see what the difference is.  A similar issue would occur at the top of the cabinet because of heat rising.  Withouy some sort of circulation system there is an uneven temp spread in the cabinet.  Finding the ideal spot is difficult.

[GusRobin]

"If I just hang the probe through the vent, it interferes with adjusting the vent. "
I leave my vent wide open. Some adjust theirs, but you should never close it all the way. While it seems contradictory, closing the vent actually reduces the temp as moisture is trapped in the cabinet. So whether or not you adjust your vent or leave it wide open, there should always be enough room to hang the probe. I also sometimes hang it through the door and just close the door on the wire.

"Also if he smoker has multiple trays the meat makes hanging it a bit problematic.
"
Not really. As stated above you can hang it thru the door.
"I would suspect that measuring below the bottom rack would be too close to the element(s) - the heat generated would not have spread out yet.  I will have to measure at that point and see what the difference is.  A similar issue would occur at the top of the cabinet because of heat rising.  Without some sort of circulation system there is an uneven temp spread in the cabinet.  Finding the ideal spot is difficult."
Most suggest that you measure the temp at the bottom rack of meat since higher up the probe can be blocked and you get a lower reading. So the meat on the bottom gets too hot compared to the top. It is better to get the "correct" reading at the bottom, the top will actually see lower temps until it all evens out but you can rotate racks if your temp is that much of a variation.
A lot depends upon the qty and placement of the meat, that is why hanging the probe gives you more flexibility than a permanent mount. But, as the man says, "you pays your money and takes your choice" It is a matter of convenience and preference.

[TedEbear]

1. Is there any reason why I cannor just "daisy chain" the second element off of the original element?  It seems that it would be easier to add wire from the first element to the second. 

That's the way I did mine.  Just a short 3-4 inch length of high temp wire from each end of the original element to the second.  I would call it wiring in parallel rather than daisy chaining.

On the location of the TC, mine is soldered to an alligator clip.  I run it down through the top vent and clip it to the bottom of the lowest rack of food.  No problem with adjusting the vent, as it should never be completely closed.

[DaWiz]

Being of a curious bent I have started some testing of the 6-rack temperature distribution.

I set the PID to 150 F for all of the tests.  I am only part way through but what I have found so dar has surmised me.

I had assumed that having the PID probe at the center of the cabinet would give the most even results so that is where I placed if for the first set of tests.  I use an Iregon Scientific wireless thermometer for checking the temps.

With the OS probe next to the PID probe there was no difference in temps.
The right front st the same level read 13 degrees higher.
The left front read the same as the PID.
The left and right rear read 8 degrees higher.
Moving the OS probe to the top rack center I got a +2 degree reading.

Now for what I suspected:
Moving the OS probe to the center of the bottom rack read 192 degrees when element was on.  It only dropped a couple of degrees when the element was off.

At this point I was curious as to how the PID would react to the element heat when coming up to temp.  This is where I was surprised.  I moved both probes to the bottom rack center.  I ran auto-tune on the PID because I was getting 8 - 10 degree swings on the PID.

After auto tuning the PID it would go to 150 and sometimes 151 degrees. The OS read 151 all the time.

Heating to et point was a little slower but it was smoother.  Took me a while of thinking but I think I know why it worked this way.

As soon as the temp would hit 150 degrees from the element the PID would turn it off.  When it would drop below 150 it would come back on.  The temp at the bottom would be kept at 150 - without the higher temps seen when the probe was higher in the cabinet.  I got a reading of 168 at the top of the cabinet.

I have a bunch more testing to do - ran out of daylight.

[GusRobin]

If you set the PID to 220 it will not run up to 220 and then shut off. It will start cycling on and off at a lower temp so that it "coasts" its way to 220. That is why it is able to maintain a tighter temp. (The more accurate it is tuned for your specific situation, the tighter the temp band)

[viper125]

Run my vent open all the time. And i keep all 4 probes down thru it. I then feed thru trays the smoker probe is placed just below the lowest rack, and the temp of meat is in the lowest rack. I also hooked them up independent and on switch. So I can turn off and use just one or turn on for both. Also if one element blows out I can shut that off and still use the working one. Ot her then removing back cover its no harder if you understand basic wiring. Of and I still keep a foil covered crick in the bottom on the right. It takes no useful space and helps keeping heat more constant. I found a cookie sheet that fits the bottom exactly. And use it to catch any thing the drip pan or bowel misses. Now that is one of the most helpful things Ive done. LOL!