HBBLVR4 Low Voltage Transformer / Relay Section   240 Volts Input - 24 Volts Output  - 25 amp current rating   8” wide accessory for the HBB series of electric hydronic baseboard heaters.  This would allow the user to operate the heater through the use of a low voltage, 2 wire thermostat.   Both the transformer and relay are integrated into one unit.  Use of this accessory also allows the user to interconnect multiple heaters on the relay side of this device, up to the maximum rating of 25 amps or 6000 watts.   For HBB Series Baseboard Heaters     HBBLVR4 Wiring Instructions