Customer had too much heat on second floor in bedroom zone, thermostat in off position, went to boiler to find zone valve stuck open, had to change ball and motor assembly due to older style where it didn’t match up, drained down zone and replaced zone valve assembly, purged all three zones, tested each zone separately, zone valves opened and closed, supply and returns got hot, also lowered temperature on aquastat for indirect tank water temperature was 160 degrees, lowered to 120, system operational. Boiler is up there in age is about 33 years old just let customer know they should start planning for new boiler in near future.