Morphing Air Conditioner into Autocascade System

[mytekcontrols]

WIth the suction line access port where do you braze that into so it doesnt freeze over?

Good point! I forgot about that.
Hmmm... my connection is almost 6" away from the suction line... could be a problem. I can insulate the line, but you are right, there will probably still be enough conduction to probably make it sweat (I doubt that it will freeze). I might need to also use some armaflex tape on the painted steel plate, and use small spacers between it and the front panel that it will eventually get mounted to. A little sweating on the exposed end of the access fitting and brass cap should be ok.

...the expansion tank?

Actually one of the access ports does go to the expansion tank as well. Both are needed due to the pressure restriction of the expansion tank captube (couldn't expect to pump a very good vacuum through 12 feet of 0.031" ID captube).

I guess if I really had a freezing problem, a piece of stainless steel tubing could be soldered between the suction line and the manifold port connection. Or a small power resistor (used as a heater) clamped to the backside of the manifold mounting plate and connected to my power would also work. At 120 VAC, a 3K 5 watt resistor would probably do it.

I'll just have to see how it goes (a bit of trial and error).

WHat the purpose of the buffer valve?

If the discharge pressure gets too high during start-up/cool-down, it dumps some of the refrigerant gas into the expansion tank to lower the amount of refrigerant circulating in the system. This reduces the discharge pressure, and then slowly meters the refrigerant back into the system via the expansion tank captube. Since the gas source is taken after the 1st phase separator, we leave the bulk of the highest boiling refrigerants (as separated condensates), to continue the work of cooling the succeeding stages, so that eventually enough of a phase change has occurred in the other circulating refrigerants to keep the discharge at a more reasonable pressure.