To open the front loading door, a 120 volt signal is applied to S1, the coil of the valve that supplies air to the load door or the heat reclaimer’s bottom port. The valve will open, and 80 PSI of air is supplied to the bottom port of the piston. The piston rod will extend, and the door will open. No voltage is applied to S2, the coil of the valve that controls the air supply to the door pistons top port so that this line is bled to the atmosphere.
To close the front loading door or heat reclaimer damper, the voltage signals are reversed, and the loading door will close.
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