Caleffi introduces its new line of hydronic heating zone controls: the ZSR101 (pictured), ZSR and ZVR Series. The new controls feature heavy-duty sealed relays for quiet operation and large screw terminals for ease of wiring and onboard ground terminals. The ZSR101 Series is a versatile single relay control with two outputs for operating a 120 VAC pump with boiler enable, or two 120 VAC devices without boiler enable. Features include: rear knockouts for 4x4 junction box mounting, convenient pre-installed jumper for pump operation and 10 amp total load rating. Caleffi.