Inventory the major systems
Record visible equipment, model numbers, approximate ages and available manuals.
Collect prior records
Keep invoices, permits, warranties, service reports and inspection documents together.
Photograph condition
Date-stamped overview photos can help compare later changes.
Create an unknowns list
Uncertain ages, missing service history and unexplained repairs deserve follow-up rather than guesses.
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.