I have a boiler with 3 zones, each zone has its own circulator pump (all replaced within the last 6 or so years).
For the past few weeks the zone on the 2nd floor was clanging really loudly when it turned on, it would still heat no problem though (sometimes it was slow but it seemed to depend on the day). This morning, the zone stopped working. Ive tried bleeding this zone, but when I remove the cap, I get a hissing noise and then nothing, water never comes.
When I went down to the boiler, the pipe leading out from the circulator pump is warm, but further up after the open/close valve, the pipe is cold.
I can post pics when I get home from work.
I know Im probably not giving enough info for help, but any suggests I would appreicate!