Primary/Secondary Copper Manifold Installation Kit for Combination BoilersSave installation time and cost with a pre fabricated manifold kit. Optimized hydronic and radiant heating performance and overall efficiency. Made with type L copper tubing. California residents see Prop 65 WARNINGS Pre fabricated manifold kit Optimized performance and overall efficiency Covered by a 1 year warranty 1 in. FNPT dielectric unions for boiler supply and return 3 4 in. FPT with plug for heating accessories 1 in. isolation valves and 3 4