Before you close on a house, you are committing to every system in it. The install years of those systems are the first facts you can get. Ask for them in writing, check them against the equipment, and write the answers beside each system.
Why the year matters
An install year is the starting point for a planning date. It is not a verdict on the system. Age tells you when the next replacement may come due, which helps you set money aside and ask better questions about the rest of the house.
Ask for the list
Ask the seller to name the year each major system was installed. Cover the heating unit, the cooling unit, the water heater, the electrical panel, and any appliances that stay with the house. Ask whether the heating is a furnace, a boiler, or a heat pump, since the planning window differs for each. Write each answer beside its system name.
Ask for the paper
Ask for the installation paperwork, the manuals, and any permit records from the local office. Ask whether the work on each system was done under a permit. A verbal answer is useful, but a receipt, a permit, or a manual is a better record of the year.
Read the plate yourself
Most major units carry a nameplate with a model and serial number. Read the plate on each system during your visit, and compare it to the seller's list. If the plate and the list disagree, ask the seller to explain before you go further.
Ask what stays with the house
Ask whether any warranty or service agreement on a system stays with the house after the sale. Terms differ, and each one has its own rules for transfer. Ask the seller and the agent to put the answer in writing, and read the terms yourself before you rely on them.
Put the answers on one sheet
Write each system, its install year, and its planning date on one sheet. Compare that sheet to the period you expect to hold the house. A system with a planning date close to your early years of ownership is one to discuss with your inspector and your budget before you commit. The Gas Furnace: typical service life and when to plan and Central Air Conditioner: typical service life and when to plan pages show the planning windows for two common systems.