Put a bigger tank on the same 1.5kW element and you wait longer for it: Ariston's AN2 15 LUX prints 25 minutes to heat its 15 litres, and the AN2 30 TOP WIFI, also 1.5kW, prints 50 minutes for 30. Litres are what the tank holds and kW is how fast it heats them, so the common mistake is reading the kW figure as the size.
The short version
Choose the litres for how much hot water you want at once, then read the kW for how long it takes to heat. At 1.5kW, 15 litres takes 25 minutes and 30 litres takes 50. At 3kW, 30 litres takes 26. And before you set two heat-up times side by side, check they are printed for the same temperature rise: two listings here use 45°C, not 35°C.
Same 1.5kW, twice the tank, twice the wait
| Model | Tank | Power | Heat-up at a 35°C rise | Minutes per litre |
|---|---|---|---|---|
| AN2 15 LUX 1.5 SIN | 15 litres | 1.5kW | 25 min | 1.67 |
| AN2 30 TOP WIFI 1.5 SIN | 30 litres | 1.5kW | 50 min | 1.67 |
| PRO R S 30SHE SIN3 | 30 litres | 3kW | 26 min | 0.87 |
| PRO R S 40SHE SIN3 | 40 litres | 3kW | 34 min | 0.85 |
21 storage water heaters live in /collections/water-heaters, censused 15-09-2026: 31 in the collection, less 5 drafts and 5 instant heaters. 6 of the 21 print a heat-up time. These 4 print it for a 35°C rise; the other 2 use 45°C and are in the next table. Minutes per litre is the printed minutes divided by the litres.
Within each power rating the minutes per litre barely move: 1.67 at 1.5kW, 0.85 to 0.87 at 3kW. The two 30-litre heaters hold the same water and finish 24 minutes apart, and element power is the only input in the table that differs between them. Step from the AN2 15 LUX to the AN2 30 TOP WIFI and you keep the 1.5kW, double the tank, and double the printed time.
Does a 3kW water heater hold more hot water than a 1.5kW one?
No. Tank size sets how much hot water you get and power sets how fast it heats. The PRO R S 30SHE SIN3 at 3kW and the AN2 30 TOP WIFI 1.5 SIN at 1.5kW both hold 30 litres. The 30SHE prints 26 minutes to heat it through a 35°C rise, and the AN2 30 TOP WIFI prints 50.
Two listings time a 45°C rise, and one product name hides its litres
| Model | Tank | Power | Heat-up as printed | Temperature rise it is printed for |
|---|---|---|---|---|
| SL 30 2.5 SIN | 30 litres | 2.5kW | 33 min | 45°C |
| PRO R S 100HE SIN3 | 100 litres | 3kW | 86 min | 45°C |
Heat-up time and temperature rise as printed on the SL 30 2.5 SIN and PRO R S 100HE SIN3 listings, read 15-09-2026. They are the only 2 of the 21 live storage heaters that print a 45°C figure.
Heating water through 45°C takes more energy than heating it through 35°C, so a 45°C time looks slow next to a 35°C one. The SL 30's 33 minutes already beats the AN2 30 TOP WIFI's 50 for the same 30 litres, and at a 35°C rise it would come in lower still.
The names are the other trap. 'ANDRIS LUX 30 1,5KW SIN' writes 1.5kW with a comma for the decimal point and gives its size as a bare 30, and the description under it prints neither figure. That 30 is litres: Ariston's Singapore catalogue lists the model's code, 3100564, as 30 litres at 1500W, and 'ANDRIS LUX 15 OR 1,5KW SIN' (code 3100565) as the 15-litre version at the same power. Most listings print no heat-up time at all. 15 of the 21 live storage heaters leave it out, including all five 707 models, which put their litres in the title and give no power figure in the description.
What does 1,5KW mean in a water heater's name?
It means 1.5 kilowatts, with a comma as the decimal point. That is the element's power. On 'ANDRIS LUX 30 1,5KW SIN' the size is the 30, in litres: Ariston's Singapore catalogue lists code 3100564 as 30 litres at 1500W.
How do I compare heat-up times printed for different temperature rises?
Only compare minutes printed for the same rise. Heating through 45°C takes more energy than through 35°C, so the SL 30 2.5 SIN's 33 minutes at a 45°C rise would be lower at 35°C. Keep that in mind before setting it against the 35°C figures on the AN2 and PRO R S listings.
Power is the first line on the listing, and capacity is the ninth
| Line as printed on the AN2 15 LUX | What it settles |
|---|---|
| 'Power: 1.5 kW' | How fast the tank heats |
| 'Voltage: 230 V' | That it matches Singapore's supply |
| 'IP Protection: IPX1' | Its rating against dripping water |
| 'Capacity:15 Litre' | How much hot water the tank holds |
| 'Heating Time (∆T=35°C):0h 25min' | Minutes to heat the full tank through a 35°C rise |
| 'Dimensions W x H x D (mm):360 x 360 x 324' | The box size to measure your space against |
| 'Safety Mark Number:190039-11' | The registration to look up with CPSO |
7 of the 13 spec lines on the AN2 15 LUX 1.5 SIN listing, read 15-09-2026, quoted as printed and in page order. Warranty is line eight, between IP Protection and Capacity.
Power heads the block and capacity turns up at line nine, which is how a kW figure gets mistaken for a size. Read capacity and heating time together, because the minutes mean little until you know how many litres they cover. The dimensions line is the one to measure your space against. For tank diameter on the PRO R S range, see where to buy a water heater in Singapore.
Does a storage water heater need a SAFETY Mark in Singapore?
Yes. The Consumer Product Safety Office lists household water heaters of the instantaneous and storage types, rated at not more than 250 VAC, as controlled goods in its high-risk tier. A controlled good has to be tested, registered and carry the SAFETY Mark before it is sold in Singapore. Six storage heaters here print the number on the listing; on the AN2 15 LUX it is 190039-11.
The two cheapest timed heaters are the 3kW ones
| Model | Price | Tank | Power | Heat-up as printed |
|---|---|---|---|---|
| PRO R S 30SHE SIN3 | $270.71 | 30 litres | 3kW | 26 min at 35°C |
| PRO R S 40SHE SIN3 | $288.37 | 40 litres | 3kW | 34 min at 35°C |
| AN2 15 LUX 1.5 SIN | $344.86 | 15 litres | 1.5kW | 25 min at 35°C |
| SL 30 2.5 SIN | $363.69 | 30 litres | 2.5kW | 33 min at 45°C |
| AN2 30 TOP WIFI 1.5 SIN | $456.68 | 30 litres | 1.5kW | 50 min at 35°C |
| PRO R S 100HE SIN3 | $466.09 | 100 litres | 3kW | 86 min at 45°C |
The 6 of 21 live storage heaters that print a heat-up time, censused 15-09-2026 and sorted by price. Prices were pulled live that day and can change; the product page carries the current figure.
Price does not climb with kW here. The PRO R S 30SHE heats twice the water of the AN2 15 LUX in one more minute, on a 3kW element, for $74.15 less. The AN2 15 LUX is lighter, 8 kg against the 30SHE's 13 kg, and its listing prints an exact box size, 360 x 360 x 324mm, which the 30SHE's does not.
So if 15 litres is enough and you want a box size to measure against before you order, the AN2 15 LUX 1.5 SIN at $344.86 as at 15 September 2026 heats that tank in 25 minutes on half the power of the PRO R S pair. If you need 30 litres in about the same time, go up in kW rather than tank: the 30SHE does it in 26 minutes.
The AN2 30 TOP WIFI costs $111.82 more than the AN2 15 LUX. For that you get double the litres, double the wait, and a touch display with Wi-Fi.
Which heater here heats 30 litres in under half an hour for the least money?
Of the six storage heaters here that print a heat-up time, the PRO R S 30SHE SIN3 at $270.71 as at 15 September 2026. It prints 26 minutes to heat 30 litres through a 35°C rise, on a 3kW element.
Related guides
707 vs Ariston Storage Water Heaters: Tank Size, Warranty and Price Compared and instant shower heaters: power, pressure and IP rating.