Henny Penny 580 Maintenance Manual page 23

The drain valve is found underneath the cookpot in the back
of the fryer. It is opened by pulling the red knob in the front
of the fryer, allowing the shortening to drain from the cookpot.
1.
rain the shortening from the cookpot.
2. Remove right side panel of fryer.
emove the two cotter pins from the drain valve fitting
and drain rod and pull extension from the drain valve, and
let rod drop down.
4. Unscrew the drain shield from the valve.
5. Unscrew drain valve from the cookpot.
6. Replace new drain valve in reverse order.