Turned on my hydronic heat yesterday for the first time this season and all three Alpha zone circulator pumps (four-years young) were seized (Display indicates “- -“ after about a minute of runtime). These pumps were last used in July or August and it’s now almost Thanksgiving.
Removed the pump cartridge from the cast-iron housing (everything was clean except for some black slime on the O-Rings) and manually turned the impeller. It made a “snap” sound and was then free to rotate. Reinstalled and repeated the procedure for the remaining two pumps and now everything works fine.
• Soft city “ground” water (Suffolk County Water, Long Island, NY)
• No glycol or inhibitors
• Boiler water and strainers are clean
• No make-up water to speak of
• Piping is 99% copper w/couple feet of PEX
• High efficiency, condensing gas boiler
• System water temp is typically under 130 deg F
Is this considered normal behavior for some relatively expensive, high-quality pumps? Any suggestions other than exercising them more often during the off-season?