A boiler control device may include a housing and a wireless communication module for receiving coded control signals from the thermostat device. The boiler control device may also include boiler control circuitry for selectively controlling activation of the boiler-based heating system according to the coded control signals from the thermostat device. An onboard antenna disposed within the housing and communicatively coupled to the wireless communication module, and an interface configured to receive an auxiliary antenna. The auxiliary antenna may be disposed outside of the housing. Detection circuitry may detect times when the auxiliary antenna is communicatively coupled to the interface. Switching circuitry may interrupt communication between the onboard antenna and the wireless communication module during the times when the auxiliary antenna is communicatively coupled to the interface.