Heated Chamber — K2 Plus¶

The K2 Plus has an actively heated chamber with a dedicated PTC (Positive Temperature Coefficient) heater element. This page explains how the chamber system works in Klipper and how to get the best results from it.

Hardware Overview¶

Component	Klipper name	Pin	Type
Chamber heater element	`chamber_heater`	`PC12`	`heater_generic`
Chamber temperature sensor	`chamber_temp`	`PC5`	EPCOS 100K thermistor
Chamber cooling fan	`chamber_fan` (temperature_fan)	`PA0`	PWM, watermark control
PTC fan (heater companion)	`chamber_fan` (heater_fan)	`!PB14`, enable `PB2`	Auto with heater
PTC power enable	`ptc_power`	`PB2`	`output_pin`, default value 1

The PTC fan (!PB14) runs automatically when chamber_heater is active. The cooling fan (PA0) runs in temperature_fan watermark mode to maintain a target_temp of 35°C when cooling is needed.

Temperature Ranges¶

Setting	Value	Notes
Chamber heater max temp	80°C	Hard limit in Klipper config
Chamber sensor max	125°C	Safety limit
Cooling fan target (passive)	35°C	Maintains ambient when not actively heating
`verify_heater` check_gain_time	345600 s (4 days)	Effectively disabled — chamber heats slowly

80°C is the hard maximum

The chamber_heater max_temp is set to 80°C. Setting a target above this will cause Klipper to shut down. For most materials, 40–60°C is sufficient.

Recommended Chamber Temperatures by Material¶

Material	Chamber temp	Notes
PLA	0 (off)	PLA warps in warm chamber; leave off or run cooling
PETG	30–40°C	Mild warmth reduces warping
ABS	45–55°C	Critical for preventing layer delamination
ASA	45–55°C	Same as ABS
PA (Nylon)	50–60°C	Reduces moisture absorption during print
PC	55–70°C	High-temp materials benefit from maximum chamber heat

Controlling the Chamber¶

Set chamber temperature¶

SET_HEATER_TEMPERATURE HEATER=chamber_heater TARGET=45

Wait for chamber to reach temperature¶

TEMPERATURE_WAIT SENSOR="heater_generic chamber_heater" MINIMUM=43

Turn off chamber heater¶

SET_HEATER_TEMPERATURE HEATER=chamber_heater TARGET=0

Check current chamber temperature¶

In Fluidd, the chamber heater appears in the Temperatures panel as chamber_heater with both current and target temperatures displayed.

Chamber Pre-heat in START_PRINT¶

For ABS/ASA prints, add chamber pre-heating before bed leveling so the chamber is warm before the first layer:

[gcode_macro START_PRINT]
gcode:
  {% set CHAMBER_TEMP = params.CHAMBER_TEMP|default(0)|float %}
  {% set BED_TEMP = params.BED_TEMP|default(60)|float %}
  {% set EXTRUDER_TEMP = params.EXTRUDER_TEMP|default(200)|float %}

  G28

  {% if CHAMBER_TEMP > 0 %}
    SET_HEATER_TEMPERATURE HEATER=chamber_heater TARGET={CHAMBER_TEMP}
    M140 S{BED_TEMP}
    ; Soak until both bed and chamber are close to target
    M190 S{BED_TEMP}
    TEMPERATURE_WAIT SENSOR="heater_generic chamber_heater" MINIMUM={CHAMBER_TEMP - 3}
  {% else %}
    M190 S{BED_TEMP}
  {% endif %}

  Z_TILT_ADJUST
  BED_MESH_CALIBRATE
  M109 S{EXTRUDER_TEMP}
  LINE_PURGE

Chamber Cooling After Print¶

For materials that must cool slowly to avoid warping (ABS, PC), keep the chamber warm during the cool-down phase by leaving the heater on at a reduced temperature for a period after the print ends:

[gcode_macro END_PRINT]
gcode:
  ; ... park toolhead, disable steppers ...
  ; Slow cool: hold chamber at 40°C for 10 minutes then turn off
  SET_HEATER_TEMPERATURE HEATER=chamber_heater TARGET=40
  G4 P600000   ; wait 10 minutes
  SET_HEATER_TEMPERATURE HEATER=chamber_heater TARGET=0
  M140 S0
  M104 S0

PTC Power Pin¶

The ptc_power output pin (PB2, default value 1) keeps the PTC circuit enabled. Do not set this to 0 during printing — it would cut power to the chamber heater entirely. The helper script macros do not touch this pin.