The combination boiler/heat exchanger from Walker Process Equipment, A Div. of McNish Corp., is a tube-in-tube-type heat exchanger on a common base with a hot water boiler. The boiler and exchanger are integrated with water piping, fuel lines, instrumentation and a complete electrical control system. Controls include modulating fuel control technology. The boiler is a dry-back, double-pass boiler heated with a forced draft burner for maximum combustion efficiency and operating dependability. The exchanger is an independent tube-in-tube design with a biosolids/water counterflow arrangement that provides maximum heat transfer for a compact heating system. The boiler maintains an inventory of water at a relatively high temperature, typically 180 degrees F, that assures optimal boiler exhaust temperature that helps prevent flue condensation. The heat-exchanger-feed water system automatically blends hot water with warm water exiting the heat exchanger on demand to maintain an optimal heat transfer. 630-892-7921; www.walker-process.com