instagas ,,,,,,,,, they are still giving batter quality ,,,,,,,, boss , golden fuji , are also good ,,, nas , canon are total junk ,,,,,,, i use 3 instagas instant heaters for more then 15 years and just recentelly grounded all of them and replaced by rinnai 6L japanese heaters,,,,,,, but in stock condition rinnai is not userfrendly ,,,,,,i have altered them and make a custom made heater ,,,, that tiny 6L heater heat exchanger is efficient enough to compete with my massive instagas water heaters ,,,,,,