Hi Sifu,

I have one storage water heater shared by 3 bathrooms). Is it possible to have 3 switches at 3 different location (each inside each room)?

Thanks in advanced.

Can.
Each room use doorbell switch
Control 1 timer.
Timer control contactor
Contactor control heater

Thanks for your sharing. 👍
Sound straightforward yet few components required for this setup. Probably will stick to 2 switches only.

use my design if you want a very long life switch.
the heavy switching is done by the contactor
and with the timer, you wont need to remember if you switched off the heater

My electrician used a relay which is controlled by 3 switches at three separate location. One is switched on, I can see the on led displayed on the other two. However, to switch off, have to be at the same switch. Cannot switch off at other location. Not three ways controls. A bit inconvenient but acceptable.

Thanks for your info sharing.

Yup. the right keyword: contactor is there. This is bulletproof no-nonsense solution.