Burned up conductors on electric furnace.

This is from Trane but most manufacturers have the same requirement:

ELIGIBILITY REQUIREMENTS:  The following items are required in order for the Products to be covered under this limited warranty:

• The Products must be in the same location where they were originally installed.

• The Products must be properly installed, operated, and maintained by a licensed HVAC service provider in accordance with the Product specifications or installation,

operation, and maintenance instructions provided by Company with each Product.  Failure to conform to such specifications and/or instructions shall void this limited

warranty.  Company may request written documentation showing the proper preventative maintenance.

• All Product parts replaced by Company under this limited warranty must be given to the servicing provider for return to Company.

• Air handlers, air conditioners, heat pumps, cased or uncased coils and stand-alone furnaces must be part of an Air Conditioning, Heating, and Refrigeration Institute