actually it can be calculated quite easily. if u have like 4 person in the household.

each person shower for approx 15 mins.

total shower time = 1hr. meaning ur instant heater have to on for 1 hr. lets say it draws 1.5kw/h so total power consumed = 1.5kw.

for storage heater. usually the heater requires more power. some i read are around 3kw/h.

turn on, leave it for 10 mins to heat up. then heaters turn off and water in tank remains hot. 30lit tank can easily accomodate 2 person showering.

4 person showering should turn the heater on for around 20-30 mins. total power consumed is about the same as the instant heater.

and u get better water pressure

I remember hearing that instant heaters use less electricity compared to storage heaters. If that is so, would it be better to install instant heaters in each toilet rather than a lesser number of storage heaters? What advantages do storage heaters have over instant heaters?

if you are the kind that wakes up immediately and shower, get the instant heater. if you are the kind that wakes up dilly dally for ten minutes then shower, get the storage heater as it takes about 15 mins to heat up. unless you leave it on all the time. good thing about storage heaters, link to all the sinks so you can have hot water to wash your dishes too. just my point of view.

actually it can be calculated quite easily. if u have like 4 person in the household.

each person shower for approx 15 mins.

total shower time = 1hr. meaning ur instant heater have to on for 1 hr. lets say it draws 1.5kw/h so total power consumed = 1.5kw.

for storage heater. usually the heater requires more power. some i read are around 3kw/h.

turn on, leave it for 10 mins to heat up. then heaters turn off and water in tank remains hot. 30lit tank can easily accomodate 2 person showering.

4 person showering should turn the heater on for around 20-30 mins. total power consumed is about the same as the instant heater.

and u get better water pressure

mine is the other way round... instant heater 3kWh, storage heater 1.5kWh. cos HDB rule says those homes with 30 Amp mains cannot storage heater > 1.5kWh

following your calculation, for my case:

2 pple, each shower for 15 mins. 15 x 2 = 30 mins.

For instant heater: 3kW/h x 0.5 hr = 1.5kW

For storage heater (switch on for 30 mins): 1.5kW/h x 0.5hr = 0.75kW

So actually i save electricity by using storage heater