How to pick a water heater
How to pick a water heater
When choosing a household electric storage water heater in Hong Kong, determine the pressure type first, then consider tank capacity and body depth according to water use and the installation space.
The following three points must be distinguished first. They concern safety, not merely whether the pipework will connect.
- Shower-type / low-pressure heater: supplies hot water to the shower only. It does not supply a wash-basin tap.
- High-pressure / unvented heater: may supply other outlets, including a wash-basin tap.
- Never install a low-pressure heater on a high-pressure installation. Excess pressure can cause the tank to explode.
Installation must be carried out by a water-heater licensed technician（熱水爐牌師傅）. The fixed electrical installation must be undertaken by a Registered Electrical Contractor（註冊電業承辦商）; the water pipes must be undertaken by a WSD designated person / licensed plumber（持牌水喉匠）. A high-pressure unvented storage heater also requires permission from the Water Supplies Department before installation.
WhatsApp: +852 9684 8806 · See also How to order and Delivery & Installation.
1. Determine the pressure type first
EMSD groups household electric water heaters as instantaneous, shower type (low-pressure storage or open type), and unvented thermal storage (high-pressure). When replacing a heater, the new unit should match the existing type unless a qualified person has inspected the water supply and pipework. An incorrect pressure type will often fail to connect to the existing outlets. Installing a shower-type low-pressure heater on a high-pressure system is not only non-compliant — it is dangerous.
| Type | Intended use | Catalogue label (this site) |
|---|---|---|
| Shower-type / low-pressure | Hot water to the shower only (shower-type / open-outlet storage). The outlet must not be connected to a wash-basin tap. | IT series — shower / low-pressure |
| High-pressure / unvented | May supply other outlets, including a wash-basin tap. Pipework is arranged for a high-pressure / unvented storage heater. Current high-pressure listings on this site are thermostatic. | ITU series — high-pressure |
EMSD warning (shower-type / low-pressure)
For a shower-type heater:
- Do not connect the outlet to a basin or bathtub — excess pressure can cause the tank to explode.
- Do not install a shower head with an on/off valve.
- Use the manufacturer-approved mixing faucet and fittings.
EMSD states that incidents arise mainly from improper installation and lack of maintenance. Official notes: Safety tips for using electric water heaters.
If the existing type cannot be confirmed, a photograph of the old unit and the pipe connections may be sent by WhatsApp for checking.
Standard installation is quoted separately. Starting fees for low-pressure storage and high-pressure thermostatic heaters differ; see Delivery & Installation. Work outside the standard scope is charged in addition.
2. Safety and licensed installation
A water heater must not be installed or modified by the householder. Installation must be carried out by a water-heater licensed technician（熱水爐牌師傅）.
- EMSD: the fixed electrical installation must be carried out by a Registered Electrical Contractor (註冊電業承辦商).
- WSD: the water pipes must be carried out by a designated person / licensed plumber (持牌水喉匠).
- A high-pressure unvented storage heater also requires permission from the Water Authority before installation. Replacement of the same type within an individual flat may be treated as minor works and handled by the licensed plumber.
Official references (government pages prevail):
- EMSD — Safety tips for using electric water heaters
- EMSD — Installing shower-type and vented storage heaters (Chinese)
- EMSD safety poster (PDF)
- WSD — Installation of unvented thermal storage type electric water heaters
Installation for larger / central storage water heaters is quoted separately.
3. Tank capacity
These are electric storage heaters: water is heated in a tank and then drawn from that store. They are not instantaneous (tankless) units. A larger capacity stores more hot water and requires a larger body.
| When this size is typically considered | Published capacities on current listings |
|---|---|
| Limited space, or lower stored-water demand | Low-pressure: approx. 15 litres; 18 litres |
| Everyday household use | Low-pressure: approx. 22 litres. High-pressure: approx. 24 litres |
| Consecutive showers, or a longer shower | High-pressure: approx. 37 litres |
The figures above are taken from current product listings (some are stated as approximate). Actual need varies with use; the product page and a site inspection should prevail.
4. Body depth — super-thin and standard
Hong Kong bathrooms often have limited depth. Super-thin bodies reduce the front-to-back measurement while retaining the listed capacity. On current listings, super-thin depth is about 180–200 mm; standard square bodies are about 266 mm deep. Super-thin units are generally taller or wider. Height, wall space and door swing should be checked before ordering, not depth alone.
5. Current listings on this site
Current listings are electric storage heaters (not instantaneous). Features stated on the product pages include a stainless-steel inner tank, a white easy-clean exterior, and 3000 W heating. ITU models are listed as thermostatic; IT models are listed as low-pressure shower type and supply the shower only.
Current low-pressure (shower-type) models: IT-4, IT-18, IT-6, IT-25. Current high-pressure models: ITU-6.5, ITU-25S, ITU-10.
A dedicated supply, pipe alterations, or a pressure-reducing / PTV valve — if required — are quoted separately. See Delivery & Installation.
Catalogue: Water Heaters · Low-pressure (shower-type) · High-pressure.
6. Information to provide when enquiring
- Pressure type of the existing heater (or a photograph of the old unit and pipe connections)
- Preferred model, if already chosen (for example IT-18 or ITU-6.5)
- District · delivery or collection · whether installation is required · whether the old unit is to be removed
- Photograph of the wall space or bathroom (optional; useful when choosing super-thin or standard)
Price, delivery and installation will be confirmed in writing. Quotations are generally valid for seven days. Cash on delivery (COD) is available unless otherwise agreed.