The E-Classic 1400 is designed to maintain hot water between 175°F to 185°F by controlling the air supply to the furnace.  The furnace supplies air to the furnace with primary and secondary air ports.  Primary air is supplied to the furnace with air ports around the bottom perimeter (sides and back walls) of the firebox.  Secondary air is supplied to the furnace with air ports in the Charge Tube (Central Boiler term for flue gas passage at the bottom of the furnace).  When the furnace is running normally (bypass outlet is closed), the flue gas passes through the coal bed and then on to the Reaction Chamber (Central Boiler's term for the ash reservoir where combustion air further reacts with the flue gases) below the firebox via the Charge Tube.  Combustion air is supplied by a blower to a plenum housing the three solenoid-controlled primary and secondary air valves.

These temperatures are measured by a thermocouple in the Reaction Chamber and I believe the air valves open as follows:

  1. The 1st secondary air valve opens whenever the furnace controller calls for heat.  Air emanates from the Charge Tube when the furnace starts.
  2. The primary air valve opens at 550°F.
  3. The 2nd secondary air valve opens at 750°F.

These temperatures are measured by the thermocouple in the Reaction Chamber. When running correctly, reaction chamber temperatures can easily reach temperatures higher than 1400°F.  Visible smoke from the chimney disappears once the Reaction Chamber reaches 700°F.

A gasifying furnace is basically creating its own charcoal by driving off the volatiles in the wood.  By splitting logs into halves or quarters, the log's surface area increases which helps the gasification process.  Since the firebox's walls are water-cooled and are always therefore below the boiling point, some smoke condenses on the walls and door of the firebox and the tarry creosote residue runs down to the coal bed.  It is necessary to loosen the ash and coals in the coal bed and Central Boiler includes a 3/8" Cleaning Rod that they recommend using every time wood is added.  They also recommend using a Stanley Wonder Bar for loosening up the creosote around the perimeter of the firebox and around the firebox door.