For most of us, a home is the biggest purchase we’ll ever make. So, naturally, we’d like to know that big, unexpected bills won’t pop up soon afterward.

In this market, lots of sellers are tossing in a promise – in the form of a one-year home warranty – that won’t happen. But buyers shouldn’t blindly accept that a warranty guarantees against any problem dealing with the systems and appliances.

“Read the [warranty] document and know what it is intended to cover,” warns Michael McRaith, Illinois insurance director.

One feature that can create confusion, shares Art Chartrand, spokesman for the National Home Service Contract Association, is that “We won’t provide coverage for something that is already broken.”

Chartrand advises buyers to always hire a qualified home inspector to determine if the heating, air conditioning and other features are in working order. In some states, inspectors will report on the condition of appliances, but it’s not standard, notes Bill Richardson, 2009 president of the American Society of Home Inspectors. If buyers are worried about unexpected costs during the first year of ownership, they should ask an inspector about appliances or check out their condition.

Another reason for a careful read, explains Chartrand, is that “These are contracts of ‘inclusion’ – meaning only named items are covered.”

Sales of warranties that sellers buy and hand off to buyers have held up, despite a drop in overall home sales, says Chartrand. The sales indicate that for those who read the fine print, these contracts are valuable, he concludes.