In this subdivision “woodheating energy system” means a wood burning appliance designed to operate as a central heating system to heat the interior of a building. The appliance may burn wood solely or burn wood in combination with another fuel. A central heating system shall include a central appliance to distribute heat by a series of pipes, ducts or similar distribution system throughout a single building or group of buildings. A wood burning appliance shall not include a fireplace, meaning a hearth, fire chamber or similarly prepared place with a chimney intended to be usable in an open configuration whether or not it may also be closed and operated closed; or a wood stove meaning a wood burning appliance designed for space heating purposes which does not operate as a central heating system or as a sole source of heat.