Majority of manufacturers warranties will be for 12 months so unlikely the installers would guarantee them beyond that period.
Should they fail before the warranty period has expired. From experience, most suppliers will replace the fitting, leaving the installer to 'attempt' to recover any 'call back' costs/labour/travelling from the manufacturer which more often than not doesn't end favourably for the installer!
Should they fail before the warranty period has expired. From experience, most suppliers will replace the fitting, leaving the installer to 'attempt' to recover any 'call back' costs/labour/travelling from the manufacturer which more often than not doesn't end favourably for the installer!