Have an old R-11 CVHE which is now having high head problems. Running at about 8 psi, I know all the reasons that could cause this prolem. Did the temp-pressure chart deal, saturated cond. liquid temp @ about 80 degrees which should be 1.5 psi cond. pressure. Just did some leak repairs, was able to pull a 500 micron vacuum and hold it. Just can't believe that it is sucking in air. My purge has not pumped out at all. Have other issues also, flow is not at design, delta p is about 4-5, design is 8.3 psi. Tower approach is really wacked out as well, 48 degree w.b. with a leaving tower water temp of 80. My condenser approach is anywhere from 12-14 degrees. I realize there are other issues, but can having tower problems, flow problems, and/or fouled tubes sqew my temp-pressure relationship. Common sense tells me I have got non-condensables, but can my other problems look like this? Thanks for your guys help!!