I am trying to control the temperature of several etched foil heaters that are currently just on a ON/OFF switch (using solid state relays). I have spoken to several individuals and just would like to get more advice. I was recommended to use a rheostat (light dimmer) or a variable transformer. I would like to control each plate separately. Each plate runs on 120 VAC at 600 W (5 A), there are 6 total plates. I think if I would use a rheostat is may burn out quickly, but if I use a variable transformer, would the heater function properly. Any advice/recommendations would be great. Thanks in advance.