Manufacturers will typically NEVER allow a warranty to exceed 2 years. If they do, you will be looking at huge cost to do so, either broken out or hidden in original price; you will pay one way or another.
What will typically happen if you put in 5-yr warranty, a hungry contractor will "promise" the warranty and cross his fingers; it won't be backed up by the manufacturer.
A warranty is for "defects in materials and/or workmanship" in the original manufacturing of the product. If your problems don't manifest themselves until after 12 months, then they were likely NOT due to either of these causes. They were likely due to bad installation, poor application of product, or #1 reason: shabby operations, i.e. not maintaining properly and passing blame off on manufacturer.
It will be EXTREMELY hard (and rare) to prove defects in materials or workmanship with a product that ran fine for 2,3, or even 4 years and then failed. If it ran that long satisfactorily, then it is close to all the proof the manufacturer needs to disclaim the warranty.
Just sayin'......