There is a Thermacube in there: It switches on the heated element under the water tank. I don’t put “more” on it, to extend the life of the internal switch* (and the heat tape has it’s own “thermostat”, plus, for the ~10 ft. of pipe it puts the heat right where needed.
*More pertinent, low load on the Thermacube means better reliability. The heavier the load switched, the more likely the switch (relay) will fail at the worst possible time or, at least, a bad time. (In freeze protection of pipes, failure is always at a bad time!) Of course, incandescent light bulbs switched on and off often have their own reliability issues...
In the long run I’ll probably have the Thermacube control a mercury wetted relay* that feeds both the heated element under the tank and the heat tape (as my suspicion is that the thermostat in the heat tapes is what fails, and I can bypass it.)
*I have a batch of “NOS” 5 amp mercury wetted relays from years back, but, what’d I do with those puppies??!! They are usually good for around 5 million cycles!
10A too, IIRC...