A house comes with its systems already in place, and most of them were installed before you arrived. The purchase is the time to learn what you are taking on. Each system's planning date starts from its install year, and that year is often easier to find in the paperwork than on the equipment.
Ask the seller for the install records. A permit card, an invoice, or a service receipt usually shows the install year and the name of the installer. If the seller cannot find them, ask who did the work. The record matters more than the name, and a written record is easier to check than a verbal answer.
Walk the house with the seller or the inspector and read each nameplate. The nameplate carries the model and serial numbers. The serial format can often be decoded to an install year, though the method depends on the maker. Copy the numbers into your notes before you leave the house.
Put these questions to the seller in writing:
- What is the install year of the furnace or boiler, the central air unit or heat pump, the water heater, and the electrical panel?
- Who did the last service on each system, and is there a written record?
- Has any system been repaired, and what was replaced?
- Is any system still under a service contract or warranty, and can that paperwork move to you?
- Has the electrical panel been changed, and is there a labeled circuit directory?
- Are there any known water, gas, or venting issues that the seller has not put in writing?
Compare the answers against the typical service life figures for each system. An older system is not a defect. It is a planning input. The question is whether the paper supports the age you were told, and whether the answers leave gaps.
Read any transfer terms before you rely on them. A service contract or warranty may end at sale, may need a form to move to a new owner, or may cover only the original purchaser. Ask the seller or the provider to state the transfer rule in writing, then read the contract itself for its start date, its waiting period, its cancellation terms, and its exclusions. Published figures on this site are general, so the contract in your hand is the source that governs.
Before you commit, set aside planning room for the systems nearest the end of their typical life, and note which ones an inspector should examine more closely. Compare what you were told against the gas furnace service life and the boiler service life pages. Keep every paper in one folder, because the records outlast the sale.