The Tekmarnet® 4 Zone Expansion Module 326 is Designed to Provide Expansion For a Zoning Solution For Heating Systems. It Can be Used in Applications Ranging From Baseboard Zones, to Radiant Heating Manifolds. This Product Expands The Number of Zones Provided With a Zone Manager by up to 3 More Zone Pumps. It is Capable of Providing Power For up to 3 Tekmarnet® 4 or Stand Alone Thermostats And Energizing Their Respective 115 V (Ac) Zones, as Well as Providing a Powered Zone Group Pump (Powered End Switch) Contact to Enable an External Device Such as a Manifold Pump. For Further Information And up to Date Literature Visit: Tekmar Documentation | Tekmar Controls | 326