The procedure for installing a baseboard heater may vary depending on the model of the baseboard. However, most baseboard heaters are installed under windows. The installation involves connecting the power supply wires to the heater's wires and then mounting the unit on the wall with screws.
First, disconnect the power supply to the room in which you intend to install the baseboard heater, and test the supply wires with a voltage meter to ascertain that they are current-free. Remove the wiring cover from the heater to make way for the entry of the supply wires. Move the heater close to the wall, and connect the supply ground, live and neutral wires to the heater's ground, live and neutral wires respectively. Secure each connection with a wire nut. Then, push the connected wires into the heater's junction box, and replace the cover.
Using a stud finder, locate the wall studs, and mark the studs on the wall where you intend to install the heater. Hold the heater against the wall, lining up the mounting holes with the stud marks. Straighten up the unit with a level, and secure it on the wall with mounting screws. Turn off the heater’s thermostat in case it is on, and reconnect the power supply to the room. Allow the heater to sit for five minutes to ensure it is faultless, then turn it on. Let it run for about 30 minutes to eliminate any oil residue.