Probably too much info here, but I thought I would share (this refers to controllers with a digital display and specific temperature settings (i.e., 180, 225,250, NOT controllers with Low, Med, High):
The "P" settings for the controller adjust the "idle fuel feed rate". When in the "smoke" setting, the controller works by cycling 15 seconds of pellet feed followed by 45 second delay (with P-2 setting) before it cycles again - essentially it stays in the idle fuel feed mode. When using temperature controls (e.g., 180, 225, etc.,.), the controller continuously feeds pellets until the temperature reaches the set temperature. It then goes into what is called the idle fuel feed mode where it cycles 15 seconds on and then "n" seconds off depending on the P-setting. The purpose of the idle fuel feed is to make sure that pellets are periodically fed into the firepot, thus keeping the fire going. The idle fuel feed mode continues to cycle until the temperature drops 3 degrees below the set temp and then the auger motor feeds pellets until the temperature rises to/past the set temp (e.g., 225 set temp and 222 degree low temp). The process then repeats and you should get temp swings that average close to the temp setting on the controller.
For most conditions, P-2 is a good balance to minimize temp swings. There are reasons to adjust the P setting, but you have to be careful or you can create more problems than you solve. Although in some scenarios changing the P-setting can increase the amount of smoke, that is not necessarily a good thing. I'll explain in detail below. If you want more smoke, I would recommend an
AMNPS or tube smoker to provide more smoke.
If it is very cold or very hot ambient temperature, it is possible that the idle fuel feed rate needs to be set lower or higher. If it is very cold, a faster feed rate (e.g., P-1 or P-0) will reduce the temp swing by feeding more pellets during the idle fuel feed mode. In very hot temperatures (e.g., North Carolina summers) it is possible that the idle fuel feed rate is too aggressive and may cause the temperature to never drop down to the target temp setting. In this case, setting to a higher P-setting (e.g., P-3) will reduce the overall amount of pellets fed during the idle fuel feed mode and allow the temperature to get down to the target temp. Each increase in P-setting adds 10 seconds to the feed delay for P-0 through P-10, 5 seconds more for P-11 to P-15.
Setting to P-1 or P-0 will worst case cause the smoker to run above the target temp. Setting it beyond P-4 increases risk of the fire going out and that can be dangerous and damage your smoker. It can also cause extreme temp swings. A setting too high will cause the fire to almost go out and then when the low temp is reached, the auger runs excessively dumping pellets into the firepot (it can overflow!). Once the fire gets started again, you can have an inferno with a blazing pot full of pellets. If you have a high P-setting and you see your smoker cycling periodically with a lot of smoke, you are likely experience high swing temps and at risk of damaging your smoker. Traeger does not recommend settings higher than P-4. For my smoker, I have experimented and I usually lose the fire at P-8 or higher.
For high ambient temperatures, I would recommend running the smoker in a shaded area, especially for long smokes.
As to the hot rod, it only heats at initial start up (most controller versions for four minutes). It will NOT re-ignite a fire that has gone out unless you turn the smoker off and then back on. The absolute worst case scenario is setting the P-setting too high, having the fire go out, then having the auger run to the point of overflowing the firepot, and finally turning the smoker off and on in hopes of getting it to re-ignite.
There are various sources that explain how these particular controllers work but the best I have read is the one available online from Ortech (original supplier to Traeger). although there are minor functional differences, the algorithm for managing the pellet feed/temperature is the same. That is, continuous feed until set temp, idle fuel feed mode running 15 seconds on and P-setting value delay, repeat of cycle 3 degrees below set temp.
