The new Series SM5 is a low-pressure, packaged, steel, three-pass fire-tube boiler of firebox design. Available in a range of sizes from 20 bhp to 150 bhp, the boilers are built to allow for through-the-door installation. They can be fired using natural gas, No. 2 oil, or both. According to the company, it features low-maintenance reliability of its proven wet-back design and is constructed according to ASME 4 requirements.