Recommend water heater

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aCuria

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feeltherain said:
I am really about the electrocuted news too so I am in a dilemma. storage type water heater I just cannot tahan anymore
Click to expand...

If you buy 3kw storage heater with small capacity, it heats up very fast. For example the Rheem EHG30 (30L). In my experience you can turn it on for 2-3 min, and the water is hot enough already.

The reason why we look for 3kw, is that the power point in your house maxes out at 13A. 240v * 13A = 3kw.

The annoying heaters are the ones which use less power, for example 1.5kw storage heater will take double the time to get sufficiently hot. The large capacity ones have the same issue, 60L will take double the time of a 30L.

to raise the temperature of 1g of water by 1C you need 4.184 joules. 30L of water by 1C is 4.184 * 30000 = 125,520j A 3kw heater supplies 3000j/s so it takes 41.84s to raise the water temperature in a 30L heater by 1C

We only need to get the water to about 37C which is about 10 degrees above room temperature, which would take 418s (7min) in the worst case

However there is another effect here which is thermal stratification. The water at the top of the tank can be much hotter than water at the bottom of the tank, and the heater draws water from the top of the tank where it is the hottest.

For this reason in practice you do not need to wait the full 7 min before showering. We only need the top layer of water in the tank to hit 37C and from experience this is achieved in 2-3 min.

There is a secondary concern here which is that the 3kw heater will heat water faster than you can use it, so as you shower the water gets hotter. With those 1.5kw heaters the water may get colder as you use it...
 
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lampano

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my ariston storage water broke down after 6yrs...
gg to change..

any good brands? i just need 20L will do.. no need for wifi completed function also
i see Ariston tio whack left right centre....alot complaints
 
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lampano

lampano

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siaoliaolor said:
I feel water storage the water not hot as much as standalone

Standalone better leh
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spore so hot why need so hot water...
i bathe wo heater 90% of time..
if not missus need ..no need at all for me
 
ceestudent

ceestudent

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lampano said:
my ariston storage water broke down after 6yrs...
gg to change..

any good brands? i just need 20L will do.. no need for wifi completed function also
i see Ariston tio whack left right centre....alot complaints
Click to expand...
Just change Joven or Rheem 30L/35L, whichever is available.
Mine is about 8 years before it start to corrode and dripping. Ok lah. Electricity also not use a lot.

I dislike to use the instant one, lousy pressure and usually can be very hot when you start opening the tap.
 
randyap

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panasonic_water_heater_dh3dl2s_1557063765_428db619_progressive.jpg

Water heater better be very basic with rccb, without superfluous functions and good to go for many years.
 
ceestudent

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Actually the rust coming from the tank is sort of expected.

I remember reading somewhere that inside the tank should have sacrificial anode and it need to be replaced every 2-3 year to prevent the rusty tank. But the storage heater sold here is purposely made as non user replaceable, obviously to let people change the new one lah. So it is not practical to change the anode by yourself.

A bit wasted actually. Gov talk a lot about green and sustainable. blah blah. But end up we just throw and change new. Bo bian, buy new one is more profitable to the company than just do maintenance.
 
haiyata

haiyata

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randyap said:
panasonic_water_heater_dh3dl2s_1557063765_428db619_progressive.jpg

Water heater better be very basic with rccb, without superfluous functions and good to go for many years.
Click to expand...


one of my previous water heater is also Panasonic. the brand is surprisingly very good.

now I using some stupid gas heater. takes forever for the water to get hot.
 
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chaiscool

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aCuria said:
If you buy 3kw storage heater with small capacity, it heats up very fast. For example the Rheem EHG30 (30L). In my experience you can turn it on for 2-3 min, and the water is hot enough already.

The reason why we look for 3kw, is that the power point in your house maxes out at 13A. 240v * 13A = 3kw.

The annoying heaters are the ones which use less power, for example 1.5kw storage heater will take double the time to get sufficiently hot. The large capacity ones have the same issue, 60L will take double the time of a 30L.

to raise the temperature of 1g of water by 1C you need 4.184 joules. 30L of water by 1C is 4.184 * 30000 = 125,520j A 3kw heater supplies 3000j/s so it takes 41.84s to raise the water temperature in a 30L heater by 1C

We only need to get the water to about 37C which is about 10 degrees above room temperature, which would take 418s (7min) in the worst case

However there is another effect here which is thermal stratification. The water at the top of the tank can be much hotter than water at the bottom of the tank, and the heater draws water from the top of the tank where it is the hottest.

For this reason in practice you do not need to wait the full 7 min before showering. We only need the top layer of water in the tank to hit 37C and from experience this is achieved in 2-3 min.

There is a secondary concern here which is that the 3kw heater will heat water faster than you can use it, so as you shower the water gets hotter. With those 1.5kw heaters the water may get colder as you use it...
Click to expand...
Why not just use instant one, way easier than this
 
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