All 3 kettles are direct natural gas fired. There are standing pilots and burners are turned off/on using temperature sensors (thermocouples) and PID contollers. The thermocouple for the mash tun is in-line after the lower the ball valve. After mash in, temperature is maintained and pretty much set and forget. Works great for mash out temperature ramp and rest as well as step mashes. Temperature is also maintained during vorlauf and sparge water. I don't think temperature drop making the tubing loop will be significant. I do need to come up will a glass lid for the grant to monitor and retain heat.
I also have a tri clover with a quick disconnect if for some reason I want to take the grant out of the loop.