Keep model and serial numbers
They are useful for manuals, service and recall searches.
Record purchase and installation
Age and warranty status become easier to establish.
Follow the manufacturer
Cleaning, filter and service instructions differ by appliance.
Track recurring service
Repeated failures can support a replacement decision without guessing at exact future life.
Safety boundary. This site is for planning, observation and records. Do not improvise electrical, fuel-burning, structural, roof-height or other hazardous work. Follow manufacturer instructions, applicable codes and qualified professional guidance.