When it comes to controlling Twin Electric Fans there are several options available.

You could just wire the electric fans to run all the time, however hooking them up with relays that are temperature controlled is a much better idea.

Davies Craig offers a rage of Digital Thermatic switches, like the #0444, #0445 or #0435 that will not only turn the fan on with temperature but stagger their start-up for a 2 staged cooling approach to help reduce the initial current spikes.

The #0500 offers the same 2 stage approach, however with some extra wiring you can turn this 2-stage control into 2-speed control. Giving your cooling system the ability to run both fans at a low and high speed.

The low-speed functionality allows for a further reduction in current spikes and noise compared to the 2-stage approach, while also moving air through a greater surface area. This helps to improve the overall stability and control of the temperature.