Tekmar Zone Expansion Module (+6 valves). tekmarNet??4 Zone Expansion Module 325 is designed to provide expansion to a zoning solution for heating systems. It can be used in applications ranging from baseboard zones, to radiant heating manifolds. This control expands number of zones provided with a Zone Manager by up to 6 more zone valves. It is capable of providing power for up to 6 tekmarNet??4 or stand alone rmostats, and energizing ir respective 24 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.