Some more threshold temperature checks were implemented (my plan was different but I had an error in the implementation. The power should be higher, and these are the actual values):

• limit power to 70 W (17.5 %) when the heaters are above 225 °C
• limit power to 40 W (10 %) when the chiller outlet is above 70 °C
• cut power when the chiller outlet is above 100 °C

This is the result:

It's obvious that the lowered power isn't enough to compensate for losses through the insulation and evaporate more galden. Some more galden is evaporated, but the slowly rising temperature in the chamber indicates that there's still not saturated vapor in there, but an air-vapor mix below 230 °C. If it was saturated vapor it would have the evaporation temperature of 230 °C.

So I changed this a bit:

• limit power to 100 W (25 %) when the heaters are above 230 °C
• limit power to 70 W (17.5 %) when the heaters are above 235 °C
• limit power to 40 W (10 %) when the chiller outler is above 70 °C
• cut power when the chiller outlet is above 100 °C

Things were a bit different now:

Now there's saturated vapor in the chamber at about t = 220 s, and a short while later the chiller outlet temperature jumps to some 90 °C. This jump could be anticipated, because some evaporated galden condensed in the chiller inlet tube, which has a short horizontal section just behind the chamber. A galden drop built up here, basically obstructing the outlet until too much galden evaporated and suddenly a lot of it got into the chiller.

The chiller reacts quickly to the increased galden mass flow, and also shows fast recovery from such a "flush".

Next:

• improve tube geometry to have less galden being collected in there. This is annoying because the teflon tube is so hard to get into shape;
• fix power setting algorithm,
• write a P- or PI-controller for the heating up state, and one for the saturated vapor state.