Compost must be kept moist but not saturated. Excess liquid from the drum strains through a stainless mesh screen into the evaporation chamber. The ideal environment for evaporating any excess liquid is a large surface area combined with heat and moving air. Sun-Mar meets these criteria in the evaporating chamber.

Any liquid not absorbed by the compost in the drum drains through the screen directly into the evaporating chamber.

On all central units the liquid falls first onto an evaporating tray and then to the main evaporating surface. The tray not only helps oxygenate this liquid, it also traps any peat mix debris, and almost doubles the evaporating surface. Evaporating trays can be removed and cleaned if necessary, through the door opening on Centrex 1000 and 2000 units, and through the drawer access port on Centrex 3000 units.

For optimum results evaporation is assisted on 110 Volt electric models by a thermostatically controlled heating element. Sealed in a compartment underneath the evaporating chamber, the heater warms the floor of the evaporating chamber without drying out the compost.

In non-electric units, although some liquid is evaporated by passive venting, the overflow drains must always be connected.