The Dunkirk EWC oil-fired hot water boiler offers up to 86.4% AFUE and is available in 4 sizes. The boiler features a dependable cast Iron heat exchanger with cast iron push nipples and a Hydrolevel Operating 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 the rate of temperature change inside the boiler and delays burner firing accordingly, maximizing efficiency by turning on the burner only when needed. In the With Coil version, the Low Limit Control seeks maximum temperature to satisfy domestic hot water call bypassing thermal purge logic.