I don't mean to bug... but this feels like it is very overpowered?
Like maybe it would be more balanced if it only added +1 to the range for every 2 steps in quality, so Rare would get 2 spaces, while Legendary would be needed for 3?
Idk, just a thought.

I thought about that, but chose to leave it as is. I don’t want other quality levels to not provide any bonus. Once you can afford legendary heat pipes, you’re likely very strong anyways

Ok
Also, could you just use all regular and then drop a legendary every 11 for the same coverage?

I have an idea about this topic.

Instead of reducing the radius, why not adjust the 'min_temperature_gradient' and 'max_transfer' of the different qualitys?

The idea is that, as quality increases, more heat is emitted. Therefore, a higher-quality heat pipe requires a greater temperature gradient in order to function as well as a reduced transfer rate since the emitted energie is spread wider. This makes it impossible to spam higher-quality heat pipes. Instead, the player is forced to use them selectively.
The following values are just rough estimates of what might be effective.