What should happen before more heating use?
The medical question and the equipment question need separate attention. After the emergency response, have the relevant fuel-burning appliances checked by a qualified service person. Follow the responders' and service evaluator's instructions about which equipment must remain off. Have qualified service personnel resolve the appliance condition before reuse, following the response instructions. CDC recommends qualified professional care of fuel-burning equipment. CDC prevention guidance.
We recommend describing the pattern clearly: who feels unwell, when symptoms begin, whether they improve away from home, and what heating problem you already noticed. Give that account without recreating exposure. Share alarm type, age, displayed readings you already saw, and maintenance records if available.
For the equipment report, ask what was checked, what was found, and what needs correcting. The concern should not be closed merely by replacing an alarm, changing a filter, or taking one room reading without explaining the appliance assessment.
Why the alarm still matters
Keep suitable CO alarms maintained according to their instructions. CPSC also notes that an alarm's test button checks the circuitry, not the sensor's accuracy. An alarm record is useful evidence; it is not a substitute for addressing symptoms and the furnace problem.
The next action is to protect the people first. Medical help evaluates the headaches. Qualified equipment review establishes what is required before the heating equipment can be used again.