According to the website its says zero risk of electrocution coz not using metal heating element.
Still dont know whether to choose Joven (RM 730 at 50L, using metal heating element and more electricity at 3kW+) or this.
Will share more if I try out the hydro one heater.

If you see the spec clearly, it didn't save much or pretty non. It selling point is the heating element.

Joven take 30min at 3kw to boil the water to 70°.

Hydro1 take 36min at 1.5kw to boil to 44°c. See the temp different.

I don't see the Hydro1 save in electricity.

30min at 3kW should be the JH35 model with 35L.

Hydro1 don’t have 30L model so let’s compare the 50L models from both brands.

Joven to 70C @
3kW takes 45mins
1.5kW takes 90 mins

Hydro1 to 44C @ 1.5kW takes 45mins, so it’ll take roughly 1 minute for 1C. To hit 70C I assume it’ll take an additional 26 minutes, so total time will be 71 minutes.

So with my assumption it performs ~26% better than Joven’s.

Please correct if I’m wrong.

So I am going to have one more water heater in my bathroom on ground floor. This bathroom has the best water pressure but unfortunately the developer did not install a water heater switch. Is it safe to add a switch? I think my old house at hometown add the switch for water heater, I just don't remember how they did it.

Thanks. Do you believe when I buy water heater + installation from shops like Sen Heng, Onking etc, the technicians should be trustworthy to handle this?

The "crappy" installation that you cited, good imagination. Though in real life we rarely hear about buildings particularly apartments or condominiums being burnt down because of a wrongly-installed water heater. Most units in apartments would have water heaters installed, and I don't think I have read about any building being burnt down because of poor installation of water heaters. For burnt-down buildings, I believe a fire arson or flying jets crashing into buildings (just like the World Trade Centre) would stand a higher chance of getting the whole building on fire.

In summary, the message I am conveying here is it's not that difficult to find a competent electrician. Of course, one can choose not to trust the electrician since you wont' know his background (unless you scrutinize his credentials for certification) but in reality, most experienced or competent electricians would do fine. Otherwise, we would hear buildings being burnt down in the news every day of the week due to poorly installed water heaters.

do u guys recommend wall mounter instant water heater or storage type water heater? what are the pros & cons?

Isit more costly to install storage type water heater coz need to reroute all de pipes right? Coz my house still empty now so if wana do it wud b dis time

Go for storage.

Instant not mean for strong pressure.

WTA:

Would you paying RM100 service charges for technician visit to inspect you faulty ceramic instant water heater and additional cost for change of part (if any).

Brought 2 units of SEERS instant water heater back in Aug 2014, 1 under utilise and suddenly the pump stop working and no more hot water recently.

1 which daily usage had its pump replaced in 2016, cost me RM250 for it (without RM100 service charge)

if similar replacement incurred, total RM350 expected. this make me think twice before making appointment with technician.

Anyone know what is the reasonable labour charge to dismantle existing water heater & install a new one?

I have the impact drill but i don't have confident to drill the wall tile 

If I just need hot water for shower in 1 bathroom, does it still make sense to go for storage water heater? Currently I'm using Joven instant water heater. I'm quite satisfied with the temperature as I don't really need very hot water for shower but I want to change to big rain shower for personal enjoyment. So far when I read in this thread seems like instant water heater is not recommended to be use big rain shower? or do you guys know any instant water heater that I can use with big shower head maybe like below type?