@Phaedrux unfortunately i am already using a duet expansion breakout board for my x and y closed loop steppers, it already uses the same expansion connector so cant use a duex5.
even if i could, it would be hard to convince myself to buy an entire duex5 one to use a thermistor port. is there a way to use some terminal on the duet2wifi board and configure it as a thermistor input.

@T3P3Tony that is one thing i can do. but im having two problems.

1. im using a finned heater, the implementation is not quite straight forward, maybe ill have to get a custom made finned heater. ok i will think in this direction.
2. i have used up the 3 available thermistor inputs for bed, hotend and chamber, not left with any more. i tried the PT100 using the official daughterboard, but its not working well, maybe due to interferences. is there a way to add more thermistors to duet 2 wifi?

@mrehorstdmd ive got a 2000 watt heater. which is insufficient. im reaching 140 celsius chamber. intend to power up to 3000 watt to reach 180 celsius.
my fan sucks air at the bottom, passes it over the heaters and spits it out at the top. so i guess ill have to keep the fan speed constant throughout the build to avoid artifacts that would correspond to whether fan was on or off.
i do have a TCO but for the chamber over temp protection. im not sure if i can connect a TCO directly to the heater, because for a chamber temperature of 180c, the heater would be at say 360c or more. gotta determine this . and also i think TCO for such high temperatures are hard to find.

@jay_s_uk thanks will upgrade tomorrow.
how to create it. can u redirect to any links or tutorials.
im a mechanical engineer, so kinda noob on this side.

@jay_s_uk couldnt find daemon.g in settings>system editor>system directory (same place where is config.g) . using RRF v2.01.
should i upgrade to find daemon.g, or is it elsewhere.

is there a way to switch on the chamber fan automatically when i set the cahmber temperature to any non zero value in the duet web control.
sometimes i set the chamber temperature to like 60celsius, but i forgot to switch on the chamber fan (its connected to Fan0 port) .
so with no air circulation over the chamber heaters, the chamber thermistor reads room temperature while the chamber heater goes to red hot temperatures.
is there a way to tell the firmware :
if (set chamber temperature >0 )
{switch on the Fan0 at 100% speed}

is this something to do with conditional g-code ?