Common sense dictates that the reptile controller has to have an outlet for a load, be it a heater, incubator, etc. It says so right in the description, something to the effect that it is intended for below gravel heaters, invariably 110vac. The very name gives it away - "controller."
As pascopal says, plug it into the wall, place the thermal probe in your water weasel, inside the bator and then plug the bator/heaters in to the controller.
It seems fairly obvious... but then I've been doing this a long time.
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Danny does make a good point which is, again, use knowledge and good tools for the job. Go ahead and build your bator from what ever you want... wood, stryofoam or a combination. Use bulbs, heat tape, etc for heat, and so on.
But control the thing with quality devices - wafer switches or some sort of electronic control device intended for such purpose. We have now been offered three that have stood the test of time:
Wafer Switches
Reptile heat controllers
Dedicated incubator controllers.
These suit every budget, so there is little need for Rube Goldberg contraptions to fulfill our task as hatcherists. I know this sounds repetetive, but it seems there is a need for that, too...