Waste Oil Boilers 20kw to 70kw Introducing the SM8 Cast Iron boilers. Combined with the Kroll KGUB55 Burner the SM8 is ideal for 15 kW to 60 kW hydronic home heating applications. The boilers are fitted with an electronic thermostat controller that is easily adjusted for different boiler temperatures & temperature differentials. The thermostat also … Continue reading SM8 Domestic Boiler