Deciding which is best an instant water heater or, storage water heater, is only something that you can decide. The purchase and installation costs are considerably higher for an instant water heater than a storage water heater mostly due to the cost of the unit and the large amount of electric or, gas energy required to instantly heat the water vs. the slow heating of the storage type unit.
The instant water heater may have some characteristics that are different from a tank storage water heater. These differences may either be of little consequence to you or, a major annoyance.
The tank storage water heater has a tank full of hot water for use, where the Instant water heater has to detect a flow, turn on, heat up and make the hot water. This results in a time lag before you receive hot water and if you are running the water at a low flow it may not even be enough to turn the unit on. Some users will find this very annoying.
On the other hand the tank with with its tank full of hot water can run out where the instant water heater will produce hot water as long as you want to run the hot water and never run out. This system can excel in multi-head showers as long as the instant water heater is large enough to meet the demand.
If you are in a climate where the winter water supply temperatures are very low the flow of hot water will be seriously reduced as the rate of temperature rise increases with an instant water heater where the storage tank water heater will be unaffected.
In the end your decision should not be made on the cost of the installation or the â€œEnergy Savingsâ€ offered. The longer service life expected from a properly maintained instant water heater is longer than a tank storage water heater, and the cost to heat the water is the same regardless of heating speed with only a small savings from standby loss. This means installation cost and â€œEnergy Savingsâ€ is a wash. So it all comes down to which heater meets your needs best and which one you will be happy with when it comes to your hot water usage.