Perfect for medium to heavy seasonal or light residential use, the Centrex 2000 NE allows for both a longer composting cycle, and larger waste volumes. When used seasonally by up to 7-9 adults, compost will normally only need removing annually each spring. In residential use compost will have to be extracted more frequently. The Centrex 2000 NE (Non-Electric) is the non-electric version of the Centrex 2000 which is fitted with a 4" vent stack. Installation of a 12 Volt fan is optional, but it is recommended for heavy seasonal, residential use, or where the installation is particularly subject to downdraft, being surrounded by high trees or hills. We also recommend the fan if you need to install a bend in your vent stack. 2000 series units are supplied with a 1" drain hose which should be connected to the 1" drain at the bottom of the unit. The Centrex 2000 NE may be used with one or more Sealand low flush toilets, purchased separately.