Tekmar Zone Expansion Module (+3 pumps). 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 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 rmostats and energizing ir 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.