For WH range of temperatures below 100C not much difference as we're not doing iron melting in furnace.

https://www.heating-element-alloy.com/artic...-and-types.html for further reading

Usually it is plastic insulation to cover the copper tank. Seldom see pure plastic heating tank.

see 5:35



see 4:16


This post has been edited by ceo684: Mar 10 2021, 08:35 PM

Nonstandard use with an external water pump that is above the spec of "max water pressure" supported by the WH can cause this issue.

Under normal circumstances it should last 10 years easily (w/o additional external pump). If using external pump need to check the pump's pressure doesn't exceed the capability of WH (max pressure it can sustain).

After 20 years I replaced the head and hose for my National 1997 era heater with Pana parts, coz of limescale affecting water pressure. Also condo mgmt replaced whole building piping and restored the pressure to pretty good level (as the original iron pipes all rusted internally)

This post has been edited by ceo684: Mar 11 2021, 01:52 AM

Most welcome

You mean this one? http://toshiba.com.my/waterheater/dsk38s5mw.html#tab
Max inlet pressure 0.3MPa = 3bar

Socket is against regulations (ref Suruhanjaya Tenaga) strongly discouraged because of the propensity of loose connection (=causes fires) and underrated (=causes fires) for any WH sold nowadays UNLESS its a 32A commando plug with proper IP rating.



Because any socket of 13A, 15A round plug is UNDERSIZED for a 3600W heater (3600/230 = 15.65A).

Plus the PE (earth) is by law (ref Suruhanjaya Tenaga regulation) need to be a direct connection (i.e. direct flight from the DB box into WH; with zero layby zero stopping zero refuelling).



Last but not least make sure you have a 10mA RCD fitted for the water heater circuit.
Also another statutory requirement.


Attached File(s)
 Guideline_for_The_Design_Installation_Inspection_Testing_Operation_and_Maintenance_of_Water_Heater_Systems.pdf ( 4.49mb ) Number of downloads: 12

A qualified electrician will be your best bet.
I installed myself, since developer already provided the point as a wire sticking out.

If you know what you are doing (since there is a socket there)
Test w test pen before starting to confirm the test pen works
Turn off the whole DB box, everything off.
Test with test pen again to confirm every wire is off.
Test again to be 100% sure.

check the cable is at least 2.5mm². If it is 1.5mm² your cables are undersized and cannot be used and you should call an electrician to install properly sized cabling from DB box.

Remove the 13A socket
Install this https://shopee.com.my/product/94486452/7647...38-1618845770.9 in place of the socket that you just dismantled.
The other end of the centon connector wire goes into the WH unit.

Technically with that Centon connector device we've cleared the electrical part.

For the physical installation most water heaters just need 4 holes for wall plugs..and another 2 holes for the shower head holder

Drilling wise covered in steps 2A-2C below. Pretty simple job if you have a drill.

For the plumbing.. if there is a water point for it that can be connected using flexihose then will be easier.. i.e. if existing is a screw fitting for tap, use a PVC nipple convert to male thread then just screw on flexihose (Hokah brand recommended and it comes in many lengths in 6" step - (ie 6/12/18/24/30 inches and up) according to ur needs.

Roughly these are the steps required
1-First need to mark the holes where to drill using the WH shell (the back part) itself as a reference. Make sure to avoid water pipe (anywhere vertically from water tap or mixer tap etc).
2A- Assuming your bathroom is tiled - need the bosch tile bit to scrape thru the tile slowly (like 5 mins or more) WITHOUT hammer mode - after gone thru already can use normal masonry bit on hammer mode
2B-If the mounting location is untiled (pure brickwall) then just hammer thru directly for the wall plug holes
2C-Shower head holder (can do this last if u need to think how high)
3-Install the WH shell
4-Connect wiring
5-Install WH front cover
6-Connect input piping and output to shower head

For recommendation.. also need your location boss, coz if we recommend KL folks and you're in Penang or JB, will be impractical

This post has been edited by ceo684: Apr 20 2021, 10:24 PM

1. Sizing of WH can base on expected runtime here https://www.aosbath.com/sizing-your-water-heater/

2. Single point of switching recommended. Having many switches will be quite a colossal feat, and is not as per ST guidelines for WH installation.
The first priority is that each unit WH is to be fitted with its own 10mA RCD.

3. Your piping must be able to handle the pressure from the pump output. IIANM it is illegal to pump syabas water direct from the main incomer, your pump if fitted, should only pump from own tangki source.

4. Additional note. For residential homes that don't have constant all hours demand for hot water like hotels...

The built in pump model has no separate button, it uses its own auto flow sensor to operate.

Hi vernee
1.AOS being SG based, may be based on shorter runtime since SG utilities OPEX quite expensive. Joven could be quoting less pax for "hollywood showers" since MY water and electricity is considerably cheaper so people tend to take long shower here.

2. ST main requirement is to be able to isolate WH completely, hence all electric WH need 2 pole switch chopping both live and neutral. It is relatively uncommon to see 2 pole switch also in 2 way (staircase OR mode lighting switch) configuration.

3. Typically pressure rating of downstream fittings will be based on by the bar of the pump. In terms of if shit happens..concealed piping if leak inside wall at the JOINTS will ultimately need hacking. Easier if no tiles. But bathroom any how also will at least have half height tiles.

I imply that most likely you will be going concealed piping, hence in that case buteline will be best idea for the pressurised cold water for less headaches. PVC class 6 or 7 will be able to sustain but the weakest link not the pipe..its still the joints.. which are ALWAYS at higher risk of leaking once pressurised. As PVC regardless class 0 6 7 all still have fundamental weak point of the chloroformed/glued joints.

For the heated unpressurised pipe from storage heater..for the pipes in the air it is wasting heat..this is supposed to be kept warm, sp for rhermal efficiency can use the pool noodle lookalike superlon round tube insulation.. 6 feet only rm2 or so nia. Yes this is the same as aircon insulation.

You must be thinking this girl siao wan..use aircon insulation for heater? If superlon, their datasheet say it can tahan up to 95C IIANM so more than enough temperature safe tolerance. The part buried inside wall wont suffer much heat loss so no need to insulate lah, but if really want also can insulate all the way (though the hacked longkang will need to be slightly larger).

As for backup plan..
Instant heater with DC pump built in typically will work for low pressure condition so you still have enough flowrate to take bath without scorching yourself..but rain shower wise will work lah..just not strong as a proper storage heater and external pump setup. For instant heater w built in pump the default handheld shower head will give good pressure, but adding on rain shower head it will not be same as hotel shower ya.

This post has been edited by ceo684: May 2 2021, 02:23 AM

It is still recommended to cut off the whole supply line into the bathroom, i.e. using DB-box-mounted 10mA RCD (or RCBO).

Wah 10 yrs ago punya question
I think he or she already bought a WH already

Yup its not terribly expensive but it is a very worthwhile investmemt aka one time off life insuramce. It is also a mandatory requirement under the law to have a 10mA RCD for WH (wet floor appliance).

This post has been edited by ceo684: May 3 2021, 11:11 PM

30mA still got chance to save life as the backup (2nd level) protection.
10mA should be the primary protection.

Anything above 50mA building is fire protected but lifes are confirmsure NOT protected. As >50mA @ 230VAC really direct to Nirvana, do not pass go..

This post has been edited by ceo684: May 3 2021, 11:20 PM


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Connect a device known as a hose to the tap.
Turn tap max flow.
Use a thumb to try to stop the water flow.
If its impossible to totally shut off the water w your thumb pressing on the end of the hose (not stuffing the finger inside the hose ya) then your water pressure is not bad.
If it can be stopped easily.. then water pressure is not that good.

Cables come in standard size for the most part.
The CSA (cross sectional area) is calculated from "one strand diameter" x "total nos of strands".

We'll assume ur talking about the solid stranded (stiff cable) not flexicord (the soft n flexible stuff used in appliances/extension cord).

2.5mm² is made of 0.67mm dia per strand x 7 strands.
4.0mm² is made up of 0.85mm dia per strand x 7 strands.

If its labelled on the cable, u can read the size from the cable.

If its not clearly labelled, still can cross check:
Using either a micrometer or vernier caliper to measure a strand, roughly u shud get the 0.67 value if 2.5mm² cable. Plus minus a little maybe 0.65 or 0.68, but if its grossly smaller like 0.5 on every strand of a supposedly 2.5mm² cable, then u know the cable is elcheapo substandard cable.

Weighing cables is inaccurate as the total weight also contain the insulation. Some substandard cable their insulation made thicker and copper made thinner, plastic is cheap ma.

4mm top tier cables go for ~RM180-185/100m roll nowadays. Was RM136 in March. Top tier e.g. Mega Kabel, Caramay, or MCMA cartel members.
You will need LNE (3 rolls).
Loose cut only worth if its short distance.. like below 15-20meter otherwise the loose cut premium is also expensive (can be 50-60% or more) depending on where you source em.

Yes you need to rewire from DB for the most part.
Specifically "DB to WH switch, then switch to WH" for L & N. And DB direct flight to the WH (unbroken earth).

Copper went up ~1st Apr, luckily manage to secure full roll for my needs.
As for the hacking.. at a very minimum (starting from WH) you need to hack the line out from WH up to the ceiling. then horizontal run from there to the DB box ceiling part. Then drop down into DB box. (ending at DB). Ask the electrician don't hangman (cut the wire ends so tight in the DB that you cannot move the MCB later on).. can pusing pusing the extra length ("extra tolerance") around the side of the DB box so that next time want to relocate/replace DB box life is easier... if hangman "cut exactly" really challenging to fit everything in place in future when everything else also 0 tolerance. Since the wire also already paid for and they will have no use for that few inches or 1 feet extra..but leaving "a bit of slack for the next guy" really helps.

It may be easier if you have plaster ceiling so only two main parts (start and end) to conceal, and minor hole to pass the cable thru beams or walls as necessary.
Concealing cost money because of the hacking. There is no harm in installing exposed PVC pipe conduit first, if money is a concern.. aesthetic wise when financially comfortable can conceal later.

This post has been edited by ceo684: May 12 2021, 09:20 PM


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A typical 3kW-class heater will work perfectly fine for normal shower in urban area.

If you're in highlands where its abnormally cold then only use 4.8kW type.

Typically condo water supply is pressurised, and after 20 yrs then pjpe start rusting if iron pipe on the inside, old 50c coin become ciggie size hole, and then they will change the building pipes (hopefully).

U can test w water hose and see if you can stop the water using ur thumbprint. Cannot stop means ok pressure.

Er.. that is going into special industrial equipment already. Have to see RS components

1.0 Generally all instant water heaters for home shower use work on AC power from TNB, SESB, and the other power company in S'wak.
1.1 These WH branch into pump and non-pump type.
1.2 for 3kw class heater with standard wiring this will work-lah.
1.3 for 4.8kw class heater ("highlands model") in short - this need special cables/wiring as it is very heavy appliance. Cannot use with standard developer wiring.

2.0 For with-pump model, there is sub category based on the pump type -
2.1 whether u want a "DC pump" for less noise
2.2 or "AC pump" maybe cheaper but this is more noisy.
2.3 Additional consideration whether there is pump pressure control, or its all automatic (no user adjustment possible)
2.4 Skip to user interface at 4.0

3.0 For non-pump type
3.1 there is NO pump inside.. so basically any non pump is the same.
3.2 Subcategory of non pump is mainly on the user interface

4.0 User interface - for me getting a WH it is better to get a push start button type like the Pana M series or Hitachi series. As those with water valve (to me) feels "cheap" since the 200 bucks model also same way of using.



5.0 Suruhanjaya Tenaga regulations say all WH circuits (wet floor places) need a 10mA RCD for your WH circuit.
5.1 This is pretty easy to install assuming the existing point is already ready.
5.2 Many people dieded because no 10mA RCD was fitted inside the DB box. Every few years, electrocution victim come out in the news.
5.3 The whole house RCD is kind of insensitive and will NOT protect you adequately, or even at all (as some are VERY insensitive) from current leakage of the WH.

An expensive WH without a proper 10mA RCD fitted is very dangerous.
A decent brand WH, with 10mA RCD is safer for everyone.

This post has been edited by ceo684: May 20 2021, 09:36 PM

Installation charges depend on SoW. This is storage heater so it need more work on the power point (as compared to the developer point usually suited for instant WH); and 4mm² cable to be used, and copper cable price skyrocketed wef 2021APR. Plus depending on how many outlets it branch out to - as compared to instant WH in a site where all points are ready by developer: drill six holes, hook up water pipe, hook up power cable..

The plaster ceiling one if just cut and patch back cut line with stopping, fiber netting shouldn't be that expensive unless painting over is included as well?