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Do Tankless Water Heaters Work When the Power Goes Out?

| Monday September 26, 2022

If you have lived in an area which experiences frequent power trips or power outages, you would know that once the power goes out, many appliances in the household would stop working. Nowadays, almost every household is outfitted with the latest and most advanced household appliances. Some of these appliances include fridges, kitchen stovetops, washing and drying machines, air conditioners and water heaters. Although modern appliances are much more advanced, if it depends on electricity to operate, it would mean that during power outages, these appliances would be negatively affected. Because of this, many would wonder if their appliance would be able to continue working even when the power goes out. 

Below, we are tackling the question of whether tankless water heaters would still be able to operate during power outages or power trips. While power outages are not as common as water rationing in Malaysia, when a power outage occurs, it would be in the best interest of homeowners to know whether the water heating appliance would still be able to operate and how to properly protect your appliance from any potential power outage damage. 

So, are tankless water heaters able to operate when there is a power outage? 

The short answer is: not without an extra battery or backup generator. The water heating appliance’s ability to operate during a power outage, power trip or power failure depends on the type of tankless water heater and the fuel source of the water heater.

Most tankless gas water heaters in Malaysian households have an internal PC board, electronic ignition, and an electronic thermostat that requires electricity to operate. These components will not operate without a power source, which means you would still have to wait for the electricity to be restored before you can enjoy your next hot shower. 


An Introduction to Different Types of Water Heaters and Their Fuel Supply

As mentioned above, whether your water heater is able to work during a power outage depends on its reliance on electricity. The fastest and easiest way to assess this is to check if your water heater is connected to a power outlet – if it is, it means that hot water would not be available until the power is back on. 


Electric Conventional Storage Tank Water Heaters

A conventional storage-tank water heater is powered by electricity, which means it will stop heating in the event of a power outage. However, water that has already been heated up to the point when the power goes out will remain hot for some time while stored in the insulated tank. If the area you reside in is prone to power outages, investing in a storage water heater would be recommended as you would still be able to enjoy hot showers even when there is no running electricity.


Gas Conventional Tank Water Heaters

If your gas storage tank water heater uses a continuous gas pilot light, it is likely that your gas water heater will continue to function normally in the event of a power outage. In cases like this, your water heater is still able to supply hot water for a few days even without electricity. If the storage water heater relies solely on gas to operate, operating during a power outage should be no issue. This would also be a good solution for areas that experience frequent power issues. 

One way to find out if the storage gas water heater operates only on gas is by checking if the water heating unit is attached to a power cord. If the water heater has a power cord attached to a power socket, it would mean that the water heater also relies on electricity to operate, meaning that it would be affected by a power outage. 


Electric On-Demand Water Heaters

An electric on-demand water heater uses electricity to heat water on the spot for immediate use. Since this water heating appliance operates solely on electricity, it will no longer provide any hot water from the time of a power outage. No hot water would be stored inside the unit as well because these water heating units do not come with an external storage tank. 


Gas On-Demand Water Heaters

While on-demand gas water heaters do not rely on electricity to heat up water, they usually have a control panel that is powered by electricity. So, even tankless gas water heaters would not work during a power outage.


Solar Water Heaters

Solar water heaters usually depend solely on a natural renewable energy source to operate. As long as the solar water heater has absorbed enough solar energy from the sun’s rays, the water heating appliance would have the ability to transfer the heat energy to the water flowing through the appliance. However, in some instances, solar water heaters are still connected to the electricity grid to provide hot water to the household. Thus, to check if a solar water heater is still able to work during a power outage, homeowners should find out if their solar water heater relies on mains electricity. 


In general, a passive solar water heating system is usually not connected to the electricity grid and would still be able to provide hot water to the household even during a power outage. However, with an active solar water heating system, the water heater usually relies on electricity to operate and thus, will not be able to provide heated water to the household during power outages. 

Keeping Your Tankless Water Heater Running During a Power Outage

For those living in areas that experience many instances of power outages or blackouts, it would be recommended to invest in a portable generator as a backup power source. This would not only help provide your water heater with enough electricity to continue operating during the power outage but will also provide enough power for other essential electrical household appliances such as refrigerators, stoves and lights to continue running as well.

Another way to prevent your hot water supply from being lost during power outages is by installing a battery backup system. These batteries are relatively affordable. They are connected to your tankless water heater and provide emergency electric power whenever your primary source of electricity goes down. Backup batteries may not work as efficiently as a generator, but it is more cost-effective compared to purchasing a portable backup generator. 

Protecting Your Electrical Appliances When There is a Power Outage

Power outages and blackouts cause many inconveniences and issues to electrical appliances. To better protect your electrical appliances, it would be recommended to unplug your electrical appliances from power sockets when there is a power outage. This is because, when the power comes back, there may be a power surge that could potentially harm the inner components of the electrical appliance. 


Rheem’s Water Heating Solutions 

If power outages are affecting your household, it would be recommended to choose your water heating appliance with careful consideration. While tankless on-demand water heating solutions may be more convenient and energy-efficient, if there are frequent electricity outages, the appliance is not able to operate and the hot water for showers would not be able to be enjoyed. In this case, purchasing a storage water heater may make more sense for your household as it is able to hold you out until the power comes back on. 

Looking for reliable, intuitive and high-quality water heaters? Rheem Malaysia offers a wide range of water heaters for both residential and commercial uses. Choose the best water heating solution to suit your needs for any circumstance with Rheem. With over 1,000,000 water heaters installed across Southeast Asia, you can trust us to deliver quality, innovative, and advanced water heating solutions to you.


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