happen.

The output of the regulator will likely try to go to its full input voltage rail
(because of the high gain of the darlingtons). The feedback loop in the
regulator will try to bring it back down to the set output voltage. It probably
can't because the gain of the darlingtons is too high, and the output stays
banged against the input rail (22V).


I dont understand what you mean by this. The voltage gain of the
darlington transistors is less than unity in this case since they are
being used as emitter followers.

I am dropping 8.5 volts at 20 amps or 170 watts is being dissipated by
the transistors. This may not be a real problem. I know my commercial
power supply of similar size only provides about 18 volts to the
collector of the pass transistors and this would result in about half
as much power being wasted. What voltage would you normally expect at
the the collector of the pass transistors. I have also thought that
maybe I dont have that much of a real problem since I doubt if the
power supply will ever be put under the same demands as it does
working into my load bank. Also I think I should add two more
transistors in paralell with the two I have. I think this would
distribute the heat better over my heat sink and have less localized
heating.

I dont think the size of my heatsink is a problem, it is probably
overkill. it is a 8in chimney type heat sink( i think that what you
call them) 8x8x10 inches finned inside and out. The transistor body is
mount on the outside withe the wires going down the inside of the
chimney. The end of the chimney is designed to take a muffin fan.

Jimmie