Bathrooms with extremely low water pressure usually have issue turning on the water heaters, as most water heaters use flow switch to turn on (at minimum consistently maybe around 2 litres / minute water flow, and water heater's heating element and built-in pump might not turn on if water flow is lower than that).

But I saw CENTON has a newly launched instant water heater (Atlantis range, shown below) with a Pump Activator function, which when the button is pressed, it will manually jump starts only the built-in pump to increase water flow enough for the flow switch to turn on the water heater. I think this function should be more important for you. Here is the Shopee link if u need it - Shower Rail / Rainshower



I suggest u to only go for rainshower instant water heater if your original water flow is already sufficient, since built-in pump, regardless of whichever brand u buy, won't cater enough water pressure for your rainshower if your original water pressure is already low.

If rainshower is a must and your bathroom's water pressure is low, I suggest u to install those external booster pump like Grundfos instead (Shopee link here).





Table above and below is taken from Suruhanjaya Tenaga's guideline. So basically for instant water heaters (common ones are from 3.6kW to 4.5kW), they will require the MCBs / RCDs to be 25A rated with 10mA sensitivity (for appliances installed in wet areas). 25A is the current rating (In), 10mA is the trip sensitivity.

In conclusion, I think u will need a 25A rated current, 10mA sensitivity, double pole (cut live and neutral) RCD. Experts, please correct me if I am wrong.



This post has been edited by Selene Yeo: Dec 14 2024, 10:12 PM

4.2kW instant water heater should only require 4mmsq cable, not 6mmsq cable, according to Suruhanjaya Tenaga's table above. If I am reading the table correctly.

A good reminder to always go for good quality cables, eg. like Fajar cables here - Shopee / Lazada

This post has been edited by Selene Yeo: Dec 14 2024, 10:11 PM