Answer: -It is actually similiar to the storage water heater in that u can connect to both toilets & sink etc. So it is not an instant water heater as it(instant) can only serve one toilet. However I was told by PUB staff at HDB that hot water will be available within 10 sec upon turning on. So I guess it is a pretty good deal. -I'm using it too for my 4 roomer.. After 6 months of usage, I feel you should this gas heater in the kitchen and install a electrical heater tank for the bathrooms. what happens is the concept of the Bosch is a instant heater with slight storage, therefore when you turn on hot water in kitchen and bathrooms, only either 1 of the taps will get the hot water.