A dry contact is a type of electrical relay output that does not provide any voltage itself but simply opens or closes a circuit for another device to use. These are commonly used on Control Boards to allow your HVAC system to communicate with external equipment like house alarms or fire suppression systems. For instance, a dry contact on a Ductless Mini Splits board could be used to turn on a remote exhaust fan whenever the unit is running. Because it is "dry," there is no risk of sending the wrong voltage to your smart home hub or other sensitive electronics. Many Commercial HVAC systems rely on these contacts for complex building automation strategies. You can find interface modules that utilize dry contacts in our Parts department. They offer a versatile way to integrate your ACIq equipment with the rest of your home’s technology. They are the universal language for cross-device communication in the world of controls.