lol........

water is such a poor conductor of electricity..........conducting through water is the least concern

hmm if like that how people actually get electrocuted from instant water heater ? they touch the conductivity part when there is a leakage ? isn't the body all made from plastic ?

when they use a conductive shower hose.

and a shower with failed rcd

 09_ST_Water_Heater.pdf ( 9.7mb ) Number of downloads: 24
this will be a long read but you can skip to slide 55 for the summary

LIFE PROTECTION
In the event water heater has leakage current to ground, i.e. [L-PE or L-other E] the 10mA RCD will trip as the input current NOT equal to output current (exceeds tolerance of 10mA).
Wet human body also can act as a very good ground.
RCD is very sensitive as it constantly compare input=output current, if at any point the difference exceed RCD tolerance, trip first talk later.
10mA RCD quality ones from top tier mfg RM160-170 for Hager/ABB
10mA 25A RCBO if you are using 4mmsq cable only RM105 from Schneider
There are other brands Made in MY cheaper than these but this is life insurance leh. This one only buy one time. No need yearly renewal premium.

why 10mA? 10mA still within safe zone. >50mA confirm bye bye if it leak through human body.


There is also other things the WH mfg need to follow like only plastic hose to be used. Although the attaching point for input output water all mandatory plastic to limit current, the metal hose is banned (although you can still buy it online as aftermarket replacement at your own risk).

FIRE PROTECTION
In the event there is an OVERLOAD the MCB will handle it.
This MCB will trip instantly if there is a BIG OVERLOAD i.e. short circuit between L-N, this is by the magnetic trip.
The MCB will close one eye for a short while if you have a SMALL OVERLOAD like 22A load on a 20A MCB.. estimate probably 7-15 mins for it to work, this is by the thermal trip.

ST REGULATION ON WH INSTALLATION
There is also spec on the electrical section like minimum wire sizing you need to pull, generally for 3kW heaters regardless storage or instant will be 4mmsq by ST guidelines, pull direct from DB, with 20A double pole water heater switch for the L-N cables and E must be continuous from the DB box to the WH. Cannot join join or loop loop nonsense.

THE PART THAT DOESNT MAKE SENSE
A typical 3kW class WH is to be respected as a 5.0 HP AIRCOND. The load amps for 3300W is about 14A.
A typical AIRCOND 1.5hp current draw hardly exceed 6-7A for 1.5hp
Yet, many wannabe faux electrician put overspec cabling (4mmsq) for AIRCOND circuit and put undersized cabling by ST regulations (2.5mmsq) for WATER HEATER

This post has been edited by ceo684: Apr 2 2021, 12:41 AM

My water heater current using 10mA ELCB at DB. should lower it to 6MA make it more sensitive?

10ma (0.01A not 0.1A) for WH good enough d.

They claim a lot of things but many are not supported by any scientific evidence. Metal heating element is still the most efficient one as heating element. Silicon compound is not any better.

I am not sure how one can believe this leaking current on storage heater bs. All the well designed brands have thermal and electricity cut off and your ELCB will trip in the event of the heating element mulfunctions. For storage heater there is no direct contact between the user and the unit. Water itself is a poor electricity conductor. It is the ions (salts) in water that conduct electricity. To be honest there are instances of people electrocuted from touching the old faulty instances water heater but I have never heard of people injured or died from storage heater leak electrocution

hmm so seems like non metal heater ,non electrocuted just marketing gimmick, another selling point it is low power.

how long can actually this heater can last ? more durable than metal heater ?

This post has been edited by Pain4UrsinZ: Apr 2 2021, 05:17 PM

Metal heating elements consist of many types. So are non metal types and silicon oxide is one of them. It comes down to the quality of the materials used.

An analogy will be diesel or petrol engine better? No definite answer depending on the design and materials.

Lower power = need more time to warm up for the same energy i.e. in short = LPPL

E = Pt = VIt

Energy = Power x time = Voltage(std 230) x Current x time

Not all WH come with RCD.

WH ELB/ELCB only work if it so perfectly leaked from L to PE (earth wire). Usually PE is 0 current as it is on standby only but if it registered current rising then only it trip.
Whereas L-other ground leak include leak through human body is covered by 10mA RCD.
L-N fault ie big overload in short circuit condition is covered by MCB.

Not all heater come with built in RCD.
http://eng-au.faq.panasonic.com/app/answer.../p/1635/c/47632
They come with ELB/ELCB but as per ST guideline says, install the mandatory 10mA RCD. At 230V very little current (50mA) is needed to kill someone.

This post has been edited by ceo684: Apr 3 2021, 01:03 AM

I suggest to go for storage water heater newer enamel-coated tank technology (CENTON, MIDEA, XIAOMI, BEEBEST), rather than the older stainless steel technology (JOVEN, ALPHA, ELTON, PECOL).

Lately CENTON has been getting lots of good reviews, and quite easily purchase via Shopee / Lazada.

Hi Sifus, need advice please. I have 5 bathrooms upstairs (4 daily use bathroom for parents and children; + 1 guest bathroom). In terms of usage, there’s a high possibility that at least 2-3 persons will bath at the same time and possibly up to 4 pax at the same time

Can I get advise on 3 questions : (assuming no rain shower in any bathrooms)

1. I’m planning to get Joven storage water heater. Would it be better to get :
A) 91L to supply all 4+1 bathrooms
(am concerned that 91L would take too long to heat up and in the event of “malfunction” all bathrooms no hot water and costly to replace vs Option B)

OR

B) 68L to 3 daily usage bathrooms (rooms are next to each other) + 25 or 35L to 2 bathrooms (daily usage bathroom + guest bathroom)

2. Whichever the option, is there anything in particular I need look into in terms of wiring/switches?
Sorry if it’s a noob question, Is it possible to have 5 way switches to control one heater tank (option A – 91L) or 3+2way switches to control 2 tanks (option B 68L + 35L). Ie, each room has their own heater switch and turns on the heater when they need to shower. Any issues if 2 persons turns on the heater switch to the same heater tank?

3. Based on the preferred options, is there a difference to the number and HP of water pumps I need, or I just need 1 as usual, at the main water inlet right after the POE filter? What HP water pump should I get? (I’m presuming I’ll need water pump as I’m installing a storage heater tank, right?)


Thank you very much in advance for all advice

Cheers!

Vern

Hi all, I would like to get your advise regarding storage water heater. The purpose is only for shower for 3 bedroom. Initially to buy 80L but after ask from the seller, he told me ;

Not recommend 1 tank for 3 bathroom. Ususally 3 bathroom sharing 1 tank.

Is it correct? Will it add cost to the wiring & plumbing? Thank you so much!

1 tank for 3 bathroom and 3 bathroom sharing 1 tank, what's the difference???

Reminds me of what we did to avoid plagiarism

It is not about the number of bathrooms u connect the storage water heater to, but the number of people showering in those 3 bathrooms at nearly the same time. Eg. if u have 3 bathrooms but maybe 2 of them very seldom u have people showering in them, then maybe it is enough.

Also, the further away the bathrooms are from the storage water heater, the longer distance the hot water has to travel, causing a lot of heat loss. Do bare that in mind if you are planning to install 1 heater for 3 bathroom, where the furthest bathroom might have generally colder water compared to the bathrooms closer to the storage water heater. And you have to be very careful where you plan to place the copper piping connection, since they are quite hot and might be dangerous for kids / pets if they are easily accessible (better to be hidden).

oh sorry . it supposed to be according to his advise

2 tank for 3 bahthroom. 1 tank for masterbedroom another tank sharing 2 bathroom.

How many people usually bath at the same time will make a difference in the "size" of the storage heater, not the number of storage heater, no?



From my previous research into this, the main issue for me if I were to have 1 tank to supply 3 bathrooms is that I can only have 1 heater switch

my current condo has a heater storage tank for master bathroom, and the heater switch is the usual spot, just before entering the bathroom. We turn on and off after each usage (2 adults + 3 kids using). Even 5 ppl bath one after another immediately, still getting enough warm water (mine is currently 68L). No issues with getting hot water upon immediate switch on, but of course if you want really really warm water, wait 3-5 minutes after turning on switch
If 1 switch for 3 bathrooms, means the users have to come out of their room to turn on and off every time they use, or unless u plan to leave it on for some time?

Having 1 huge 80-90L tank will also take longer time to heat up compared to 1x60L (2 bathrooms), 1 x 30L (master) tank

Logically, I would presume Hot water piping is dependent on your room location and the heater storage tank I guess. But the quote I received was lump sum eg. hot water concealed piping to 5 bathroom = RM5k.

Even with 1 tank to masterbedroom and 1 tank to other 2 bathrooms, the switch has to be strategically located

having 2 tanks definitely should be more ex as the "lump sum" quotation for piping wouldn't differ much (assuming contractor does take into account length of hot water piping required) but the storage heater tank is the one which will increase your budget. eg. of my previous calculation (pricing are estimate from lazada/internet sources),

Joven (with installation, average about RM300-RM350 per tank)
2tanks for 3 bathrooms :
JH-68 with install RM1270
JH-35 with install RM1015

(will also need to budget in wiring x 2)

VS

Joven JH-91 with install 1420

Do remember to budget in shower head and mixer (does cost quite a bit when x 3)

This post has been edited by vernee26: May 21 2021, 09:58 PM

As mentioned above, it is about 'the number of people using it at the same time' factor that we need to take into account when choosing the capacity (and if one is not enough, then multiple storage water heater), and not the 'the number of bathrooms' factor.


Something like this (look at the recommended number of users table):




And the other factor is the distance between the storage water heater to the bathroom (or bathrooms if the storage water heater is shared amongst few bathrooms). The shorter distance the better. Longer distance should cost more on the piping / hacking side + heat loss.

Dear Selene & Vernee, thank you so much for the clear explanation. i do now know which one fit my requirement