Why are more DC relays being used in hot and cold side equipment today?

The use of more DC relays in hot and cold side equipment today is primarily due to the fact that the output from most solid-state controls is DC voltage. As technology has evolved, there has been a significant shift toward utilizing solid-state devices, which operate using direct current. These devices often provide more precise control, better reliability, and the capability to handle varying load conditions.

As the industry gravitates toward these solid-state controls, integrating DC relays becomes more advantageous. DC relays can quickly switch on and off without the mechanical wear that traditional relays endure, making them a suitable match for systems powered by DC outputs. This transition enhances compatibility and ensures efficient operation of the overall system where these relays are employed.

The other options may have their merits but do not encapsulate the main driving force behind the increased use of DC relays as accurately as the relationship with solid-state control outputs does.