A home warranty pays repair or replacement costs for the mechanical systems and built-in appliances that break down in a home. Warranties can be purchased by either the buyer or seller in a real estate transaction. When the seller is paying for the warranty, it is usually paid for and goes into effect at closing. The coverage period is normally one year. Usually, central heating and air conditioning systems, electrical, plumbing and major appliances are covered. It's important that you read the policy closely and understand what is and is not covered. The cost for a one year home warranty typically runs between $300 and $450, depending on the size of the home and the specific types of coverage. In addition to the policy premium, there is normally a deductible of $50 - $75 to pay when making a repair claim.