Sometimes a piece of lime can get caught in the impeller. Maybe when you take the pump out it dislodged and it starting running. Its a good idea to run the pumps a couple times during the summer. My domestic pump would not start this fall, its a Armstrong Astro. There is a cap you can remove and turn the impeller on them with a screwdriver, I did and It been running for about 3 weeks now. Sometimes they are just stuck!
Greg Steinacher
This is the EXACT comment I made in an earlier post on here...that I did NOT run my pump during the off season and last October 2012 when I lit the furnace off, I noticed the pump was NOT operating. I did have a back up pump and installed it.
There was a couple fellas on here...one I believe is a Hardy dealer who said the pumps should not lock up and that it was due to the rust blocker solution I had in the boiler. I emphatically stated that the rust blocker was fine and that is was junk from my well water. I took the pump apart and sure enough, there was a piece of sediment wedged in the pump so as to NOT allow it to turn.
This past summer I let the same brand pump run all summer long and upon start up I had NO issues...so either allow th pump to run all off season...cost just pennies to do so, or run it every so often during the summer...BUT UNDER NO CIRCUMSTANCES TELL ME OR INSIST UPON ME THAT IT IS THE RUSTBLOCKER AND NOT THE PUMP!