Note- I also posted this in the Boiler forum since the topic seemed to fit both areas. Apologies if this violates cross-posting rules.
Have a 2-story house with one-zone hydronic baseboard heating (upper and lower floors are piped separately, but only one thermostat). This is an old house with heavy cast-iron baseboard radiators.
All rooms get heat EXCEPT one room on the upper floor. Naturally I expected to get air when I opened that room's radiator's bleeder valve. Instead I got lots of cold water and no air coming out (circulating pump was running).
What now? Clearly water is getting into this radiator -else I wouldn't get (cold) water out of the bleeder. After bleeding, the inlet side wasn't even a little bit warm.
Could the outlet side (downstream of the bleeder) be clogged?
Could the inlet valve be faulty (only letting water flow when there's a big pressure differential)?