Abstract: A heat exchange tube for an HVAC system can include at least one reduced diameter section with an integral flattened ridge. The flow of combustion gases through the heat exchanger tubes may be partially constricted inside the reduced diameter sections. When installed in an HVAC system the integral flattened ridges may be angled to intercept the flow of air outside the heat exchanger tubes.

Abstract: A heat exchange tube for an HVAC system can include at least one reduced diameter section with an integral flattened ridge. The flow of combustion gases through the heat exchanger tubes may be partially constricted inside the reduced diameter sections. When installed in an HVAC system the integral flattened ridges may be angled to intercept the flow of air outside the heat exchanger tubes.

Abstract: The invention relates to a novel furniture frame system comprising horizontal and vertical frame members which can be arranged in a variety of configurations to provide at least one continuous concealed channel for cables such as power and/or signal cables, in which the channel is easily accessible for wiring, maintenance, rearrangement and storage of cable without disassembly of the frame system and provides for access to cable outlets at work surface height so that cable devices can be connected to an outlet with minimal interference to the work surface. The frame system itself does not interfere with the work surface. The horizontal frame member has an opening on the top surface which is at work surface height for access to the cable channel, and also has a cover for the opening which has at least one flexible edge to enable cables to pass in and out of the channel when the cover is closed and permits the cable to move freely along the length of the cover.