Perfect for medium to heavy seasonal or light residential use, the Centrex 2000 AC/DC allows for both a longer composting cycle, and larger waste volumes than the Centrex 1000 AC/DC. The increased surface area in the evaporation chamber coupled with the larger heating element also provides better evaporation on electric units. When used seasonally by 7-9 adults, compost will normally only need removing annually each spring. In residential use compost will have to be extracted more frequently. When used residentially by up to 4 adults, some compost will need to be emptied into the finishing drawer once every few months. The Centrex 2000 AC/DC features a 370 watt thermostatically controlled heater in a sealed compartment under the unit and the standard Sun-Mar 30 watt turbo fan, with a 2" vent stack to remove the evaporate and fresh odors. This may be used when the unit is in AC operation. For easy switching between AC and DC mode, the Centrex 2000 AC/DC requires that 2 vent stacks be installed to handle the separate venting functions. The 2" vent is in use when the AC fan is in operation, and the 4" vent is venting the unit passively when there is no power available. As an extra option, we include a 12 Volt 1.4 Watt fan with the Centrex 2000 AC/DC. You may want to install this fan if the unit is to see maximum capacity use, and you should install the 12 Volt fan if you have to put any bends in the 4" vent stack, as you will then lose the "chimney effect" advantage of a vertical stack, and will need to provide air movement with the fan. You may just install one vent if you only plan on using one function. If, for example, you do not have 110v AC power yet but anticipate getting it in the future, you can install just the 4" vent and leave the 2" vent capped off. The Centrex 2000 AC/DC is supplied with a 1" drain hose which should be connected to the 1" drain at the bottom of the unit. Click here for more information on handling excess liquid. The Centrex 2000 AC/DC may be used with one or more Sealand low flush toilets, purchased separately.