When I was printing PETG on the Zero with a 255 C nozzle and 80 C bed, the passively heated chamber temperature reached 61-62 C, and that’s probably when the heat break fan pushing hot air was insufficient to keep the heat break cool enough to prevent a clog.
Keeping the front door closed but removing the glass top reduced the chamber temperature to 50-52 C. I was surprised it wasn’t cooler than that.
I had procrastinated but was planning to make 3D printed insulated tiles for the inside of the Zero but I’m now thinking that might be a bad idea. Most materials that could benefit by a heated chamber have a hot enough bed temperature that the passively heated chamber will be warm enough soon after the print starts. The only real advantage of insulating the chamber would be to reach the desired chamber temperature sooner and have enough excess heat that the exhaust fan could maintain a very stable chamber temperature, but I’m now thinking that the electronics on the extruder aren’t going to like the elevated temperature much beyond what a passively heated chamber will reach. The QIDI printers with actively heated chambers only reach 65 C and they print all types of exotic high temperature filaments.
I should finish the front door to complete my SV08 thermally insulated enclosure as the SV08 could use some passive chamber heating.