If you insulated your chamber well, the heated bed is all the heater you may need. My chamber for my CR-10S stays between 45 and 50C with the bed temp set at 100C.But I like to reduce all variables so I use an Inkbird temp controller which I hook up to a hair dryer (warm) and a small vent fan (cool), this maintains the temperature within a few degrees no matter what the room temp (it's an unheated shop).