The variable speed core blower in the system is used to circulate air through and extract heat from the brick core. A heat call from the thermostat energizes the supply air blower which begins to circulate air through the duct work. A discharge air sensor monitors the current discharge air temperature and determines whether or not the discharge air temperature is warm enough (determined by value set in L048 and L049). If the discharge air temperature is too cool, the core blower is energized to draw heat off the brick core until the desired discharge air temperature is satisfied.
Power is sent to the core blower from the base I/O relay board through the blower terminal. The amount of power sent to the blower depends on the current blower speed as indicated in Location 120. The variable speeds range from 0 to 255. For example, a speed of 255 in Location 120 would indicate that 240VAC should be present between the L2 240 terminal and the blower terminal on the base I/O relay board as shown on the Blower/Damper Activation Chart.