Hydronic heat is quiet and even until a circulator stops moving water, a zone valve sticks, or the system loses pressure and the low water cutoff shuts the boiler down. In older Mansfield, SD homes without forced air, that usually means one or two rooms go cold while the rest of the house stays warm, or the whole system stops.
Check that the pressure gauge reads in the normal range and that the reset button hasn't tripped before assuming the worst. If you smell gas near the boiler, shut the gas valve and leave the area. Stop and call if the boiler won't hold pressure, keeps shutting off, or radiators stay cold room by room even after bleeding.
An independent local plumber can diagnose and repair boiler and radiator systems, including pre-season checks before the first hard freeze in Mansfield, SD. Call (844) 898-0295 to get connected with a boiler and radiator plumber.