New user questions about PID& ambient temp


 
A

AZarett

New member
<disclaimer> Total HM New-B.
I did search around and tinker, but still not totally sure of the following :

1. Is a thermistor for tr1 included in the kit version for ambient temp ? I couldn't find TR1 on the schematic, but I was thinking it would be near the probe jacks. I dont know if I have one on my board or not. I saw references to selecting the thermistor from the probe type drop down, but I dont get a reading when I do that, so I'm guessing I dont have a thermistor.

2. I saw instructions for manual tuning the pid. I didnt see anything specifically about auto tuning (but I assume the answer is 'put values at default and cook something' )
I left my hm sitting for a day on my desk with a setpoint and no blower motor connected, so I assume I have skewed the pid learning. should I simply return the values to B=4 P=3 I=0.005 D=5 - or should I reset or dump some other file / data ?
Since I sometimes like to use the blower just to get the temp going nice and high, ( sear a steak ) whats the best way to do that without giving false data into the hm, since I dont put the probe on the grill when I'm just trying to run the blower - should I set pit temp to 0, and use the menu/button on the hm to set the fan to on ?
 
The thermistor for ambient temperature is or I really should say Was, an addon part that attaches to two of the legs of the 3rd meat probe jack. Its was never accurate, as heat from the heatermeter would give it a false reading. Just using an extra probe would do the same thing and be more accurate, as you could move it away from any heat sources.


The pid settings shouldn't need to be change, until you have a good understanding of how to run the heatermeter on your smoker. If after you run the heatermeter and you get a nice stable temperature, and you see what looks like a sin wave start to develope, then you may need to adjust the values. I have been running an heatermeter for years and I try adjust my smoker (uds) to run with the stock setting as much as possible, so that I dont need to remember them if I change to another heatermeter or accidently reset it back to stock. The PiD is not auto tuned, so you can run it all you want any where you want and it will still be the same.
 
Thanks for the feedback.
The reason I assumed the PID auto-tuned, is the values in mine now are B=0, P=4, I=.02, D=5 . I didnt change these values (unless I did it accidental playing with the menu butons) , and they appear different from what was said to be the default.
My smoker went over temp by about 25deg on my first cook. I have a BGE, so there is only 1 place for air to come in and 1 place to go out. I feel like at one point in the cook, I may have had to lid open for a while - I know I exceeded the lid timer, and the fan kicked in. I didnt pay close attention, so im not sure how long I had the lid open ( could have been 5-7 minutes) maybe that is where my over temp came from. That was Ribs, and I usually do a 2-2-1 style cook, so there are some points where the meat is being tended to. I will probably make my lid timer a bit longer. My real use for the HM is Brisket and Butt's, and I never open my egg till the end of the cook, so I wouldnt expect same issue. The egg just doesnt like to come down on temp once it goes up, so I'd hate to see it overshoot and hold.

I'll have to go re-read the PID info, and see if I should change P & I back to default.
I had an Auber Ins. PID for about 10 months - but they discourage you from tweaking the PID.
Thanks.
 
The default PID values were changed a while back, you cited the older default values in your first post. If you have a new build you will see the new default PID values, there was no auto tune performed. The default PID values should work reasonably well if your grill is sealed up properly (I tend to run closer to the old default values) If you have a common grill somebody might be able to suggest better PID settings, or after you get more familiar with how it works you can tweak them a bit by yourself. You dont have to worry about it retaining memory from being out of the pit or high heat cooks or whatever, it will adjust real quick to whatever you are instructing it to do and the temps it reads.

On the overshoot, if your grill isn't sealed up well the HM may struggle to hold the temp down low, so make sure your other vents/doors/lids etc are sealed well. Even with a sealed grill cooks with frequent opening for basting or whatever can be tough to keep low and slow. If you are doing lots of lid opening it could help a bit to manually set lid mode before you pop the lid to prevent the blower from ramping up for a sec before lid open is detected. Since air through the HM blower is not restricted a fire can draw air through it freely even when the blower is off, a damper of some sort is a good way to tamp down overshoot if the problem persists. I made a ping pong ball valve (search the forum for it) that works pretty well and also put together the roto damper that is servo controlled by the heater meter, or you could rig up some kind of gravity flap valve too..
 
Does anyone out there in this forum have both a HM and an "auto-tune" system such as the BBQ Gurus, Rocks Stoker, etc? I would really love to see a HM graphing a pit temp-only long-term burn of one of these control units doing their thing.

I have been reading how people set their Party-Q (or similar) and they "lock in" to their temperature with no fuss or muss.

I am dubious and would like to see some empirical evidence without dropping the cash to buy one.
 
RalphTrimble said:
My HM "locks in" on the target pit temp rock solid, do you have problems holding a steady temp?
Click to expand...

It isn't so much about the HM as it is about wanting to see the commercial solutions' performance.

Again, I am dubious that a Party-Q type solution can hold steadier temps than a HM and I haven't seen anyone support their commercial units' performance beyond, "I went to bed at X time and woke up at Y time and the temperature held the entire time."

I have spent enough time looking at squiggly lines to know that it probably isn't the case.

Heck, my kitchen oven's sawtooth performance is put to shame by my HM controlled smoker.

Just curious to see if anyone here has ever documented any commercial solution's real performance.
 
Oh, got ya... you want to see someone run a commercial unit and stick a probe from a HM in the pit to graph it's performance. I have no idea how well they will perform, though most of the commercial units are just on/off with the blower rather than having variable speed, so the stoking action is more of a puff-puff-puff. IMHO the HM blows them out of the pit, and with the servo support nothing else comes close.
 
Just my .02 but, I dont see a reason to doubt the Party-q, particularly if your concern is over long term temps, low/slow - I think most controllers handle that fairly well.
For the most part, the more you pay, the more you get. (feature wise) But I feel like my Auber holds temp as well as my friends stoker.
http://www.nakedwhiz.com/productreviews/partyq/partyq-4.htm

I dont own a party-q to compare to.
But I bet I could borrow my friends stoker. What test would you want to see ? Load empty smoker with same amount of fuel, and run it for x hours at x temp ? - then empty it and do same test with other controller ? posting both graphs ?
 
The last KCBS competition I attended there was a guy with about 8-10 steel keg grills, on most of them he had whatever controller that has the hose that connects to the grill (can't remember what the name of that one is?). What would be nice is to see 3-4 of those kegs fired up at the same time, put the HM on one and several variety of commercial units on the other 3. Then put the 3 HM food probes into the grills with commercial units and watch the HM graph showing all four controllers in real time on the same graph.
 
RalphTrimble said:
What would be nice is to see 3-4 of those kegs fired up at the same time, put the HM on one and several variety of commercial units on the other 3. Then put the 3 HM food probes into the grills with commercial units and watch the HM graph showing all four controllers in real time on the same graph.
Click to expand...

Exactly what I was thinking.
 
FWIW, I think the HM makes squiggly lines because it takes a lot more data than is needed to cook BBQ. You could probably sample every 5m & then adjust output/temp & have a smoother line, but the BBQ would still taste the same. Zoom out, step back, take a drink of beer & enjoy the ride.

I think one of the best pork butts I've done involved a hose because the keg got away from me (it takes hours to recover from a 100* overshoot, ask me how I know.....) I just told everyone the crispy outside was 'carnitas style'.
 
If you back out from the 1 hour view to the 6 hour view the graphs will smooth over. Depending on how clean your probes read you may see the 1hr graph look squiggly, or not... HM's prior to v4.2 didn't have the RC filters on the probes so the readings would fluctuate more, my graphs are much smoother since I moved to v4.2, which is also good for the servo setup, because the servo will bounce a bit reacting to noise as if it was a rapid temperature swing. Also, thinner probes will generally react quicker to temp changes so if you are using thin probes expect more fluctuation. To stabilize the pit probe you can use a thermal well, basically meaning, put the probe down into something that will somewhat isolate the probe from the rapidly changing temps around it caused by air flow etc.
 
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