Does anybody have any insight on the internal design of the heat exchange that would explain a 30psi drop on the source. Yet the heat pump works just fine. In an effort to clean out my Climate Master 036 open loop, water to water heat pump. I took a piece of foam under pressure with water and ran it through the source input side to clean the interior pipes. And it worked pretty well. So I did it again and it worked again. Feeling lucky I did it a third time and it never came out. I just assumed it would be a hollow pipe. Even when I reversed the water direction, it didn’t come out. Since then I have register about 30psi going into the source side. Prior to that I swear it was only a few psi. And this was about 5 years ago. But the heat pump continues to run just fine. I since have tried marshmallows, but those don’t work very well on scraping the interior piping. Or their disintegrating because of the damage the foam did. Question: are you supposed to see 30 psi on the source input side? Or did something bend because of the foam I ran through. I can’t imagine that the foam would last all these years and continue to offer blockage. How is the piping designed?