Hydronic baseboard bleeding problem

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)?

Are you sure the valve to that radiator is open? I have seen the handles become striped. Check to be sure the stem is turning with the handle.


John

Pretty sure. I opened it so far that the stem shot out of the valve and water spurted out. Also, water came out the bleed valve.

pbaxter said:

Pretty sure. I opened it so far that the stem shot out of the valve and water spurted out. Also, water came out the bleed valve.

Click to expand...

Replace the valve. If the stem came out it is no longer working. The water you are getting out of the vent is coming from the return side of the baseboard. Both ends of the baseboard must be open to promote circulation.

John

Good point. I'll look into taht.
Thanks!