Anyone have any experience trying to clear something blocking my hot water pipes? Thought it was air but after purging air from other zones, one zone would not run/purge/circulate at all. Exploring further, we found one of the round rubber closers on a valve was missing and we suspect it is now plugging the line at some unknown point. We tried back flushing (forcing water the wrong way through the open thermostat valve) but no luck. Next the heating reapirman is bringing a nitrogen tank and will try some higher pressures. I think this could be harmful to the soldered joints but have no other things to suggest. Any help or ideas are welcome.
I just went through this on a large commercial job, it was a real pain. Best of luck. Look for a fitting down line of where the item started out, mine ended up being in a close rough 90. Nitrogen wouldn't move mine at all.