Hi all, my second story heat and ac is a hydronic system with the air handler in the attic, it is fed by a boiler in my basement. I’ve noticed that the fan continues to run after the thermostat temp is already satisfied and the heat is actually off. I know some run time is normal, but how much? It’s ran for up to 20 minutes after.

There Is an aquastat, clamp on style, on the hydronic heat pipes in the attic, could this be the problem? could there also be a fan limiter on the unit?

other than the fan running a long time everything works as it shoukd

thank you