These systems can heat water for the entire house, with the burner activating automatically when any hot tap is turned on. The temperature is thermostatically controlled, usually set to a safe 50°C. Most models are computer-controlled and adjust heat based on demand, with remote control panels available for convenience. 

Since no hot water is stored, there are no standing heat losses. However, BRANZ research shows that homes with instant hot water tend to use more. Continuous flow systems have a flow rate limit, so a shower may lose pressure if other taps are used. Choosing the right size is crucial. 

Though they are the most expensive gas option to buy and install, they are the cheapest to run, especially for larger families.

 Key benefits: endless hot water and space-saving. 

Main drawback: increased water usage due to the convenience.

If you don’t have a street gas connection, a cylinder-swap LPG system is a good alternative.