Control is relevant when we are uncertain what is the cause and what is the effect. This is often the case with medical research and Pd-D cold fusion experiments. Here however we only have two variables that we are measuring. We are measuring electricity in and all the rest is excess heat (lots of it!). Therefore using control is not required, because control would only tell us information about the efficiency of electric heat resistor. If this had been unknown, then using control would have been required. But we can just assume that electric heater is e.g. 95% efficient (this is very well known science) and we do not need to study it experimentally. We can just measure the enthalpy using professional calorimetry and substract used electricity. and we get the amount of excess heat. Nice and clean.
Controls are only for experiments when we have multiple unknown variables. Here however we have only single unknown variable that we are measuring. Things would be complitely different if we cannot trust our professional calorimetry. Then we would need to calibrate it using controls were heat output is known. —Jouni
