Short answer
A warranty claim goes to the manufacturer's authorized service network for your product. Have the model number, serial number, install date and proof of purchase ready, then call the manufacturer's service line or the authorized service company for your area. Terms vary by manufacturer and product line.
Record the model and serial number from the data plate when the unit is installed, and keep the order confirmation. Those details are what a claim needs, and they are harder to reach once the unit is built into a line.
Most commercial equipment warranties are void if the unit is installed in a residential setting.
Many manufacturers also require installation by a qualified, licensed installer following the installation manual, especially for gas and hardwired electrical equipment. Read the warranty terms before installation, not after a fault.
Updated · By Norpex · Edited by John