Draft controller: Schebler Chimney Systems
Schebler says its Sequence Draft Control™ (SDC) design service offers boiler and hot water heater manufacturers a complete engineered venting system. SDC is capable of maintaining the desired condensing dew point of combustion, preventing excess draft which impacts efficiency and fuel/air ratio’s – especially with high turndown modulating burners.
This system uses Schebler eVent™ Series dampers at the outlet of each appliance. This modulating damper with pressure transducer maintains the factory recommended firebox positive pressure or negative draft condition at all times. The damper accounts for appliance firing rate – anywhere between high fire and low fire — stack temperature, outside air temperature, and other operational anomalies such as summer/winter operation and appliance proximity to the common stack.
Excess or uncontrolled draft can also impact the combustion CO2% — critical for condensing boiler and water heater applications to achieve the desired increased efficiencies. Excess draft impacts the condensing dew point (moving through the outside air reset schedule curve) which impacts the desired efficiency capabilities that condensing boiler and water heater designs offer.
Sequence Draft Control™ also improves system start up by reducing excessive draft conditions. The damper is placed in a pre-purge position to allow easy ignition and eliminate flame failure conditions which are typical in common vented systems.