Quote Originally Posted by mytekcontrols View Post
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.


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).


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.


That makes sense and would help alot.

Sweating schraider valve will be fine i think. When looking at your
drawings i was interested why there was a access valve on your expansion
tank and though you might have used that to charge and tune the system. I
know when using rotarys with cascades and tunning mine freeze over big
time and you cant remove the refrigerant gauge hose unit will you have
turned the system off and left it for ages. If i take it off even when its
almost defrosted my schraider valve leaks gas which stuffs my charge up.

So i was trying to decide for the cascade im building now to have 2 low
side access points line in your autoC and use the one on the suction line
for vacuuming and then use the one on the expansion tank for charging??
You think thats ok?? or any suggestions. I like you idea of bring all the
access valves together at the one point, will make tunning much easier
with the case all done up.