Compost needs to be kept moist. It should not, however, be saturated. To avoid this in a Sun-Mar composting toilet, excess liquid drains from the compost mass through a stainless steel mesh screen, where it collects in an evaporation chamber. The essential difference between the non-electric or 12 volt NE model and the 240-volt electric model is the provision of a heater under the evaporation tray in the electric unit. The difference between the two types of model is explained below.
On all microflush systems, 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 2000 units, and through the drawer access port on Centrex 3000 units.
For optimum results, evaporation is assisted on 240 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.