The invention provides for an upgrading of equipment without the potential problems in replacing the existing system. A relay mechanism is interposed between the existing remote sensor and the existing controller, and between the existing controller and the existing remote operational mechanism. The relay mechanism permits the existing system to perform as before while allowing the signals from both the existing remote sensor and the existing controller to be monitored by a new and isolated replacement controller until such time that the existing controller is isolated allowing the replacement controller assumes operational duties. In this manner, the upgrading of the system is done without the costs of down time nor the potential for catastrophic results.