Abstract: A warm-air furnace is adapted to provide diagnostic enhancements and more robust installation. In an embodiment, sensing equipment aboard the furnace is used to determine a first performance metric during installation of the furnace. That performance metric is then compared with a baseline metric that may have been obtained at a factory in order to obtain a performance variation value. At least partially in response to the performance variation, a notification is provided to a user. The notification may be an indication of poor installation or shipping damage, present failure and/or predicted future failure, for instance.

Abstract: A modulating gas burner control system using closed loop feedback from a flame rod which provides a signal that varies with gas pressure and which provides combustion air fan control to accurately control the heat from the system without use of expensive control valves.

Abstract: A fault detection system and method for a warm air furnace is provided. A sensing circuit connected to an AC power source measures a level of current consumption during several points in the warm air furnace operating sequence. The measured level of current consumption is compared with an expected value. If the measured level exceeds the expected level by a threshold amount, a fault in the warm air furnace may be detected. An indication of at least one warm air furnace component that is most likely to have caused the fault may be provided.

Abstract: In a climatization system the influence of the outside air temperature is fed to a comparator which is also fed with a comparation voltage, successively variable during the starting time and obtained from a pulse generator of variable pulse-time-relation, and the climatization process is started at a balance point between the two voltages.