Hi,
Sounds like you need some way of controling your heat sources - I recomend a thermostat over a dimmer if your room has variable temperatures.
You can use one thermostat to control both the cool side and the warm side if you use a dimmer (rheostat) between the coold side heater and the thermostat and adjust it correctly.
If you are using incandecent bulbs for heat then you really should buy a proportional thermostat but if you are using only CHE's and UTH's then you can use an on/ off type.
dr del