HVAC PANEL is cycling or onoff control to meet part load conditions. If building only needs half the energy that the system is designed to deliver, the system runs for about ten minutes, turns off for ten minutes, and then cycles on again. As the building load increases, the system runs longer and its off period is shorter.
One problem faced by this type of control is short-cycling which keeps the system operating at the inefficient condition and wears the component quickly. A furnace or air-conditioner takes several minutes before reaching "steady-state" performance. "Well," you say, "why not just lengthen the time between starts to avoid short-cycling?" This is possible but at a cost of some discomfort for short time. The longer the time between cycles, the wider the temperature swings in the space.

HVAC PANEL is cycling or onoff control to meet part load conditions. If building only needs half the energy that the system is designed to deliver, the system runs for about ten minutes, turns off for ten minutes, and then cycles on again. As the building load increases, the system runs longer and its off period is shorter.
One problem faced by this type of control is short-cycling which keeps the system operating at the inefficient condition and wears the component quickly. A furnace or air-conditioner takes several minutes before reaching "steady-state" performance. "Well," you say, "why not just lengthen the time between starts to avoid short-cycling?" This is possible but at a cost of some discomfort for short time. The longer the time between cycles, the wider the temperature swings in the space.