HydroTherm, a Mestek Co., has introduced the PB Series, a new and improved line of energy-efficient, oil-fired boilers ideal for use in single family homes, apartments and condominiums. PB Series boilers are up to 86% efficient and combine rugged cast iron construction with a deluxe insulated metal jacket. The boilers feature an oversized combustion chamber for enhanced, clean combustion and quiet operation. PB boilers are available in eight sizes ranging from 91-249 MBH, and can be used to provide steam and/or water heat. Extra-deep cast iron sections are 4- 3/4 inches, offering larger water content and increased water surface in the boilers.