The SW Series II, side wall vent oil boiler with or without Tankless Water Heater is available in 3 sizes from 91 MBH to 175 MBH. The SW Series II features a Honeywell High Limit and Circulator Relay Control with digital temperature display and diagnostics. In the Less Coil Version: The control monitors water temperature and delays the burner starting until any residual heat has been transferred. Thermal purge logic measures rate of temperature change inside the boiler and delays burner firing accordingly, thus maximizing efficiency by turning on the burner only when needed. In the With Coil Version: The Boiler utilizes a Honeywell non-thermal purge High Limit, Low Limit and Circulator Relay control. The SW Series II features a Limited Lifetime Warranty (Residential Applications).