The warranty for Burnham boilers made by the U.S. Boiler Company can be found at U.S. Boiler's official website. The warranty posted there applies to all U.S. Boiler Company water and steam boilers.
To find the warranty for Burnham boilers, go to www.usboiler.net, and mouse over to Resources on top of the screen, scroll down to Manufacturer's Warranty, and left-click it.
You will have to enlarge your monitor screen to read the type. You can do this by holding the Ctrl key and hitting the + key on the upper row of your keyboard. Beneath the last line of the warranty there is a button on the screen you can click to download the document.