This is one the most crucial aspect of choosing the right air bed. There are several mechanical parts – pumps and remotes that tend to fail. There are also hoses and seals that may wear out. So it is important to check if warranty cover not only sagging of the mattress but also its mechanical parts.
Mechanical parts are usually covered only for the first few years, sometimes as little as 1 year. Typically you are responsible for shipping cost of both, failed and replacement part. After the initial non-prorated period, you will be responsible for a portion of the total cost of replacement part plus the shipping costs.
As the construction varies from model to model so does the warranty. Be extremely diligent to learn about the warranty of any given product. Excessive sagging is typically referred to as an indentation/imprint/depression greater than 1.5”.
Most warranties start with a full mattress replacement for an initial period of time, and change to a limited (pro-rated) warranty as years go by. While comparing air bed warranties, you can find full replacement warranties for as little as 1 years and as high as 10 years, with overall warranty duration up to 20 years.