measured the power required to heat the new chamber to ~40C in order to design the driver circuit.

The heating consists of four silicone insulated heaters wrapped around the chamber, forming two identical halfs consisting of two heaters in parallel each (all heaters have the same power density)
both halfs can be connected in series or parallel, depending on our decision to drive more current or have a higher voltage.

I measured 11V / 0.47A for half of the heaters to reach a chamber temperature of 41.5C, so my guess is that we should connect them in series a power them by a single 24V power supply.
Total heating power required for 40C is therefore about 10W, compared to about 25W for the old chamber, even the new one is not totally insulated yet.