For temp control i use this thermostat, and 2 years on still going strong.
Seen here in my initial setup about 2 years ago
It has two temp probes each controlling one power outlet, and one on a timer only for lights.
The heat cable touches the nest on the bottom left side, away from the watertower on the right side of the nest.
The part that is touching the glass is just barely touching it, to keep the glass warm enough to not get condensation. But it's not the main way the nest is heated, that's the parts in direct contact with the nest walls. The part on the glass has a tiny air gap across most of the top It only takes a tiny bit to keep condensation from happening.
A little later i tape heat cable onto the left side of the nest too, so it goes under it, then makes a loop on the left side, then goes across the top to warm the glass a little.
You can see the silver tip of the temp probe inside the nest. It too is more to the left away from the water tower closer to the heat source.
This helps allow the small nest to have a temperature gradient form warmer to cooler. With the heater turning off when the temp probe reaches target, which will be hotter nearer the heat source, than farther away from it.
Here in a later nest i made again the main heat is applied as far from the water tower as it can be, the temp probe is located closer to the heat source than the water tower. When the temp probe is temp X. WE can gauge that closer to the heat source is going to be hotter than X and farther away from the heat source past the temp probe, will be temps cooler than X.
It is important to give the ants a temperature gradient so they can choose optimal for themselevs.
In the large nest they move the late stage brood to the hottest part for a while, then back to the most humid area for a while (the water towers).
While early stage brood are kept in the water tower areas all the time.
this happened in the mini hearth too, with late stage larvae and pupae piled up by the heat cable side while eggs and feeding larvae were kept on the water tower.
Seriously i love the thermostat, it makes life so easy to just check the temp readout once a day to be sure it is working as expected.