When heat runs
If it only happens when the heat is on, write that on the work order.
Some leaks follow heating cycles: expansion, circulation, or a heating-pipe failure. Some domestic lines just sit in a warm chase and drip when the building wakes up. The note should say which system lost water, if anyone checked.
Ask whether a heating gauge moved.
A pressure drop on the heating side is a heating clue.
Ask whether domestic hot water was also running.
Morning heat and morning showers coincide. Do not mix them.
Do not turn the building heat off as an experiment.
You can freeze other lines. Isolate locally if you can, and call.
Questions people ask
Is this in-floor heat?
Only if the building has it in that room. Ask before assuming.
Can we wait until spring?
Not if the ceiling is wet now. Seasonal waiting is how small leaks become failed drywall.