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charliechaplinspants
If that is the case, then what, in your humble opinion, is the cause of the OP's problems, and what would be the solution?
Expanding water will compress the air inside the rad, taking up the expansion. Come on, even the OP has managed to work that much out.
Can`t see that curing his pressure drop
Also, why would creating extra expansion space in a rad have cured the problem?
Dunno, you seemed to have backed up his explanation, why ask me?