They are the biggest maker and supplier of this style of water heater - the noritz tankless hot water heaters are produced in huge numbers based on a long experience.
Starting out with success in their home country, Japan, Noritz have grown to lead the world with their tankless gas water heater range.
The noritz tankless water heaters come sized for every household. These are on-demand units, which means there is as much hot water as you need, whenever you need it, without the need to store gallons of hot water in a tank.
The largest of the noritz tankless hot water heaters weighs in at a hefty 13.2 gallons of hot water per minute. There are few households that will need more hot water than this!
Of course the biggest unit costs the most money, and there really is little point in buying tankless gas hot water heaters beyond your need. With the exception of luxury units like whirlpool baths which need a fair bit of additional hot water, the general trend is currently to use less water in appliances rather than more.
This is a trend set to continue - in any case it makes good sense to fit low flow faucets and shower heads and buy energy star rated products as and when replacements are needed. So buy an on demand tankless gas hot water heater that is carefully sized to your needs. Anything else would be wasteful.