Ive had one of those(500w) for several years worked well, but as mentioned previously for “any” heater you should have a separate primary controller and use the apex as a monitor/shutoff in the event the heater or primary heater controller fails, reason being heaters have a high current draw and cycle on/off numerous times,if using the apex as the only controller the particular heater outlet/relay may fail sooner than one will imagine because of those factors.and to the point someone made before … anything that uses electricity to generate heat does make ur electricity bill go up… lol