9 Interesting Facts About Water Heaters

Let’s dive into some lesser-known facts about water heaters, and what makes them so invaluable today.

1. Heat pump water heaters use free air heat to heat water

Instead of relying on electricity or gas, heat pump water heaters absorb heat from the surrounding air to heat water. They transfer this free heat into the heater tank. 

Heat pumps are ideal in places with tropical climates, like Singapore. They  operate at high efficiency in temperatures above 15ºC. Heat pumps are not as efficient in cold climates where they are only functional for about 6 to 8 months. 

Heat pumps can work all-year-round in Singapore. They are the reverse of an air-conditioner, but with much lower running costs because of our hot climate. Compared to solar heaters, they save more. Solar saves 50% of energy compared to a heat pump that can save 80%.

2. Aircon linked-water heaters don’t work so well

An aircon water heater uses heat from the aircon compressor to heat up hot water. 

It seems energy-efficient in theory, but this couldn’t be further from the truth. You’ll need to turn on multiple aircons in 3 separate rooms for 12 hours before they can heat up a small 30-litre tank. Aircon heaters end up consuming more because users are forced to use more aircon to get hot water.

Want an energy-efficient unit? Go for a renewable energy water heater instead. 

Turning on air conditioner

3. The Romans used solar water heaters

Did you know the Romans were already using solar heating 6,000 years ago? In Roman baths, the sun’s rays would heat the windows, reflecting heat into the water. This method could sustain temperatures up to 37°C indoors, even if it was -1°C outdoors.

On cloudy days, Romans used a water heating technology known as the Hypocaust. The hypocaust is a furnace that circulates heat between the ground and floor. 

No matter how primitive these ancient healing techniques were, it is still nice to look back and see how far solar water heating has come. Modern solar heaters still share similar principles with ancient technology.

The Romans used solar water heaters

4. Water heaters should last 10 years

The average lifespan of a water heater is estimated to be 10 years. But today’s heaters in Singapore can last only 5 years. Why? In today’s globalised world, manufacture of heaters are usually out-sourced and that results in a quality control drop.

Choose a factory where heaters are made in-house. The higher quality standards will give you better peace of mind and save more money in the long run. 

Water heaters should last 10 years

5. A Norwegian engineer invented the first patented water heater in 1889

Norwegian-American engineer Edwin Ruud patented the first successful automatic storage heater in 1889. Many consider him the father of the modern water heater. His unit made it more accessible and convenient for households to get hot water.

Ruud’s water heater was also much more energy-efficient than previous hot water systems. It was the first heater to use a heating element to heat water in an insulated tank.  For the first time, water could be stored at a constant temperature. This reduced the amount of energy needed to heat the water.

6. Water heaters account for up to 18% of a household’s energy use

Water heaters have high energy consumption and can take up to 18% of a household’s energy usage! An environment of rising energy costs have given us some great energy-efficient appliances. As homeowners, it is important to select a green heater to reduce running costs.

If you’re buying a new water heater, check its energy efficiency with the Energy Factor or EF rating. It is an international standard that measures the water heater’s energy consumption. The higher the EF, the more energy-saving the unit is.

Water heaters account for up to 18% of a household's energy use

7. Use the temperature control feature to save energy

New water heaters have temperature control features. These can help you maximise energy savings. It is best to lower your thermostat from the default 70ºC to 50°C.

In Singapore, 50ºC will provide enough hot water for a family of four. 50ºC is also the best temperature to prevent bacteria growth.

8. Timer functions are great if you keep forgetting to power off

If your water heater has a timer function, use it. The timer is designed to help you save energy and money. If there are members in your family who keep forgetting to power off, a timer will come in handy.

Should you need hot showers before going to work, set your usage hour on the timer. The timer goes off when you leave the home and reduces energy wastage. Timers lower your monthly energy bills since you only heat water when you need it.

  1. O. Smith Gen 6 and Gen 8 digital water heaters have built-in timers. Their digital control panels allow you to schedule your custom usage times. If you have a Gen 1 heater and want to add a timer function, you can link the unit to a smart home system.

9. Storage heaters give you 2 times more water pressure than an instant heater

Tank-style heaters store hot water in a tank and maintain it at a set temperature until required. This means that a steady supply of pressurised hot water is always available. 

In contrast, instant water heaters or gas heaters heat water on the go. As the heating is instant, you may experience pressure and temperature changes.  

If you are planning on using a rain shower or bathtub, go for a storage heater over an instant heater. Storage heaters are the default choice for 5-star hotels. 


Interested in more water heater facts? AOS Bath’s water heater specialists in Singapore are your go-to experts. Get in touch with us to learn how we can help.

Frequently Asked Questions On Facts About Water Heaters

What water heater size do I need for a family of four?

A 40-litre Gen 6 digital heater can provide enough hot water for a family of four. A household with more people may require a larger capacity water heater tank.

The time it takes to replace a water heater depends on the complexity of the job site, and type of heater being installed.. A skilled technician can usually replace a water heater in about 2 hours.

It is not worth repairing a heater if the costs exceed 50% of the heater or if the system is over 8 years old. 

Yes. If your heater is more than 8 years old and is experiencing issues frequently, it is advisable to purchase and install a newer, more energy-efficient model.

Water heater replacements and installations start at $270. Expect to spend over $450 if you have a false ceiling.

Look out for the following signs it’s time to replace your water heater:

  • Age of the unit
  • Higher electricity bills
  • Tank corrosion
  • Frequent repairs
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AOS Bath Team