Determine the amount of time you need the hot water – Eg: household of 4, showers 30 minute each.
Trying to decide if a instant or storage heater would be better for your home? One consideration you would want to include in your calculation is the electrical consumption of both. Here is a simple method you can use to calculate:
First estimate the amount of time the hot water is needed in your home. For this example, we would assume a household of 2 pax each showering 1 hour on average a day
As such, amount of time hot water is needed = 1 hour x 2 = 2 hour
Instant heater: Assuming power consumption for your model is 3kw, that would mean the power consumption per day is 2 x 3 = 6kw.
Storage heater: Assuming you it takes 2kw per hour to heat up the entire tank. To reach the desired temperature it takes 15min in between heating up and switching off. Per day you switch on the heater say 4 time (2 bath for 2 person per day). Total time switch on is 1 hour (of pre heating) + 2 hour of showering at 2kw per hour. therefore total consumption is 6kw per day.
*above calculation does not factor in current water temperature within the heater tank
So there you have it, a simple guide to calculation (you will notice storage heater does have more consideration than instant heater).