An instant shower heater is an electrical appliance that happens to be plumbed in. Stand in front of one in a showroom and you can judge the spray pattern, the finish and how big the unit really is. What you cannot see is how much power it draws, what inlet pressure it needs to fire, or how well it is sealed against water.
Those numbers live on the product listing. Not every listing publishes them.
What four live listings actually publish
Three of these four publish a spec block. The fourth publishes a nine-item feature list and no numbers at all. Figures below are read from each product page as written.
| Published spec | 707 Kingston | 707 Wellington | Ariston Aures SM33 SB | 707 Princeton |
|---|---|---|---|---|
| Price (SGD, at time of writing) | $469.62 | $315.44 | $148.30 | $319.00 |
| Power rating | 3.3kW | 3.3kW (listed as "Rated Rating") | Not published | Not published |
| Voltage | 230V a.c | 230V a.c | 230 V | Not published |
| Ingress protection | IPX5 | Not published | IP25 | Not published |
| Permissible inlet pressure | 0.1MPa to 0.3MPa (1 to 3 bar) | 0.1MPa (1 Bar) to 0.3MPa (3 Bar) | Minimum 30 kPa (0.3 Bar) | Not published |
| Minimum water flow rate | 2L/min | Not published | 2 Lit/Min | Not published |
| Recommended water flow rate | 4 to 6L/min | 4 to 6ℓ/min | Not published | Not published |
| Water connection | Ø15mm (1/2" BSP) | 1/2' BSP | 1/2, 15 BSP | Not published |
| Weight | 1.8kg | 1.6kg | Not published | Not published |
| Published warranty | 2 years heater parts, 5 years heater element | Not published | 5 years on heating elements | 10 years, stated against the stretchable hose bullet only |
Prices are current at the time of writing and can change. Check the product page for today's price.
Power, and what your distribution board has to carry
An instant heater takes its heat from the circuit at the moment you shower. There is no tank warming up quietly over the previous hour. The 707 Kingston shower set publishes a power rating of 3.3kW at 230V a.c. The 707 Wellington publishes the same 3.3kW at 230V. Divide it out: 3,300 W at 230 V works out to roughly 14.3 amps while the heater is running.
That is a real electrical load, and a real question for your distribution board. A showroom demo unit runs on the showroom's own supply, wired and protected for a display bay. It tells you nothing about the circuit in your flat.
Take the kW figure and the voltage off the listing and give them to a licensed electrician before you order. Sizing the circuit and its protection is their call, not something to work out from a product page.
The Kingston listing also names an Earth Leakage Sensing Device, Double Safety Anti-Scald Protection and an Overheat Indicator. The 707 Princeton lists an Anti-scald Safety Device among its bullets. Both are published claims you can read before buying.
Inlet pressure and minimum flow
An instant heater needs water moving through it before it will fire at all.
The Kingston publishes a permissible inlet water pressure of 0.1MPa to 0.3MPa, which its own listing states as 1 to 3 bar. It needs a minimum water flow rate of 2L/min and recommends 4 to 6L/min. The Wellington publishes the same permissible range and recommends an inlet pressure of 0.1MPa, or 1 bar. The Ariston Aures SM33 SB publishes a minimum water pressure of 30 kPa, which is 0.3 bar, and a minimum water flow of 2 Lit/Min.
So the bottom of the Kingston's permissible range is 1 bar, while the Aures states a minimum of 0.3 bar. That is more than three times the difference at the low end. If you are on a high floor, or you already know your pressure is weak, that is the number worth looking at.
The Kingston's listing names an Inverter DC Booster Pump as part of the set. The Princeton's nine bullets name no pump. That is the clearest difference between the two listings, and a photograph cannot show it to you.
IP rating and what it does not tell you
The Kingston publishes an ingress protection rating of IPX5. The Ariston Aures publishes IP25. Both carry a 5 in the second position, the digit covering protection against water jets. They differ in the first position: the Aures declares a 2 for solid objects, while the Kingston publishes an X, meaning the solids rating was not declared. An X is not a zero.
The Wellington and the Princeton publish no IP figure at all.
For the full scale and what each digit covers, we broke it down in our guide to bathroom IP ratings.
What a showroom does better
A showroom lets you turn the knob and feel the resistance in it. You can put a hand on the casing and judge the build quality yourself, see the unit at its real size next to a person, and look at the finish under room light instead of in a product photo. No listing does any of that.
The honest version is narrow. A showroom answers whether you like it. A listing answers whether it will work in your flat. Buying well means getting both answers, and they come from different places. We went through the wider trade-offs in buying bathroom fixtures online versus in a showroom.
One more thing worth knowing before you choose: an instant heater and a storage heater are sized on completely different terms. We compared tank sizes, warranties and prices in 707 versus Ariston storage water heaters.
Common questions
How much power does an instant shower heater use?
Both the 707 Kingston and the 707 Wellington publish a rating of 3.3kW at 230V a.c. At 230 V, 3,300 W works out to roughly 14.3 amps while the heater is running. Not every listing publishes a power rating, so check the product page before you order and give the figure to a licensed electrician.
What water pressure does an instant shower heater need?
The 707 Kingston publishes a permissible inlet water pressure of 0.1MPa to 0.3MPa, stated on its own listing as 1 to 3 bar, with a minimum water flow rate of 2L/min. The Ariston Aures SM33 SB publishes a lower minimum of 30 kPa, which is 0.3 bar. Minimum pressure varies between models, so read it off the listing.
What does IPX5 mean on a shower heater?
The second digit is the water rating, and 5 covers protection against water jets. The X in the first position means the solids rating was not declared, which is different from a zero. The 707 Kingston publishes IPX5 and the Ariston Aures SM33 SB publishes IP25, so both carry the same water rating and differ only on solids.
Do all shower heater listings publish full specifications?
No. Of the four listings compared here, three publish a spec block and the 707 Princeton publishes a nine-item feature list with no power rating, voltage, IP rating or pressure figures. A feature list tells you what the unit has. Only the spec block tells you what it needs.
Compare specs before you buy. Every published power rating, pressure range and IP figure sits on the product page itself. Shop rain showers at ThatRenoStore.