chamber heating fan - auto on when you set chamber temperature

chiranjeevi

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 ?

jay_s_uk

@chiranjeevi you can do that with daemon.g
something like

if heat.heaters[2].active > 0
  M106 P3 S255
else
  M106 P3 S0

that assumes that heater 2 is the chamber and fan 3 is the chamber fan.
you can check the object model plugin to find the right info

mrehorstdmd

I have a 500W heater in my printer, with a fan that blows over it to keep it from getting very hot. The Heater is switched by an SSR driven in bang-bang mode. The fan is a 220VAC unit that is wired to the same SSR, so when the heater is on, the fan is on. The heater and line voltage are 117VAC. The fan turns slowly and quietly as a result, and doesn't stir up the air inside the printer so much that it will cause ABS prints to warp.

For safety, there should be a TCO wired to cut line power to the heater if it gets too hot (I haven't installed one yet, but should). Mounting the TCO is the tricky part- it should probably be mounted directly above the heater so that if the fan dies, the rising hot air will trigger the TCO. Don't use a self resetting TCO- if there's a fault condition, you don't want it happening over and over.

chiranjeevi

@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.

jay_s_uk

@chiranjeevi if you're using 2.01 then there's no option that I know of. You'd have to upgrade to 3.x.x.
Even then, daemon.g won't exist u til you create it

chiranjeevi

@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

@chiranjeevi https://docs.duet3d.com/en/User_manual/Tuning/Macros#daemong

chiranjeevi

@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.

T3P3Tony

@chiranjeevi another approach is to add a second temperature sensor on the heater and then set the fan up to turn on whenever your chamber heater got above a certain temperature.