I've recently been tuning my Recteq RT-590 to manage startup temperature overshoot, and I noticed something interesting about how these settings impact performance after opening and closing the lid.
After reducing the Minimum Feed Rate (MFR) to avoid excessive overshoot at startup, I also observed improved performance when the grill was recovering from a lid opening. At the end of this temperature chart, I opened the lid and allowed the grill to cool slightly. When I closed it, the temperature recovered quickly with only a slight overshoot—about 5°F—before stabilizing.
For those unfamiliar, the MFR determines the minimum amount of pellets fed to keep the fire lit during low burn rates. By fine-tuning this setting, I’ve reduced the risk of generating excess residual heat in the burn pot, which could lead to overshoot during recovery periods like this.
The key takeaway is that a lower MFR appears to create a balance that helps the grill avoid large temperature swings, both at startup and after the lid is opened. While the PID controller does an excellent job reacting to temperature changes, the MFR plays a supporting role by ensuring that the baseline heat doesn’t overwhelm the PID’s adjustments.
For those experimenting with this, remember that MFR settings may vary based on the type of pellets you’re using. Hotter-burning pellets like hickory may require a lower MFR than milder pellets like apple. Small adjustments (as little as 0.5%) can make a noticeable difference. (Also, some have noted that too low an MFR can result in larger variance around set temperature when holding temp. Of course, there is a chance that a low MFR with poor pellets could cause a flame out.)
This balance means the grill can maintain steady performance across various conditions, whether it’s during long cooks, startup, or recovering from a lid opening.
Has anyone tried similar adjustments or have insights into how MFR and PID interact in your grill setups?
Images included below for reference.
This was in mid-cook, when I wrapped the brisket.
Set temp is 225. The grill had been on about 4 hours at that point.
This is at the end of the 12 hour cook. I left the lid open longer, just to make sure the RTD experienced a significant drop in temperature. Note the steep climb back up to set temp and again, only 5 degrees over as the PID settles it back down.
After reducing the Minimum Feed Rate (MFR) to avoid excessive overshoot at startup, I also observed improved performance when the grill was recovering from a lid opening. At the end of this temperature chart, I opened the lid and allowed the grill to cool slightly. When I closed it, the temperature recovered quickly with only a slight overshoot—about 5°F—before stabilizing.
For those unfamiliar, the MFR determines the minimum amount of pellets fed to keep the fire lit during low burn rates. By fine-tuning this setting, I’ve reduced the risk of generating excess residual heat in the burn pot, which could lead to overshoot during recovery periods like this.
The key takeaway is that a lower MFR appears to create a balance that helps the grill avoid large temperature swings, both at startup and after the lid is opened. While the PID controller does an excellent job reacting to temperature changes, the MFR plays a supporting role by ensuring that the baseline heat doesn’t overwhelm the PID’s adjustments.
For those experimenting with this, remember that MFR settings may vary based on the type of pellets you’re using. Hotter-burning pellets like hickory may require a lower MFR than milder pellets like apple. Small adjustments (as little as 0.5%) can make a noticeable difference. (Also, some have noted that too low an MFR can result in larger variance around set temperature when holding temp. Of course, there is a chance that a low MFR with poor pellets could cause a flame out.)
This balance means the grill can maintain steady performance across various conditions, whether it’s during long cooks, startup, or recovering from a lid opening.
Has anyone tried similar adjustments or have insights into how MFR and PID interact in your grill setups?
Images included below for reference.
This was in mid-cook, when I wrapped the brisket.
Set temp is 225. The grill had been on about 4 hours at that point.
This is at the end of the 12 hour cook. I left the lid open longer, just to make sure the RTD experienced a significant drop in temperature. Note the steep climb back up to set temp and again, only 5 degrees over as the PID settles it back down.
