Why Is My Instant Water Heater’s Temperature Not Consistent?

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Increasingly families in Singapore are opting to install an instant water heater in their homes since it is compact and will help reduce the electricity bill. The instant water heater is usually directly connected to the shower.

One of the common water heater problems faced while using the instant water heater is that the water temperature fluctuates, especially if the tap is switched on and off. This can adversely affect the bathing experience for the user of the instant water heater. Some of the reasons why the temperature changes from hot to cold are listed below so that you take suitable corrective action.


Low Water Pressure 


One of the reasons the water is not getting heated is that the water pressure at the inlet is low. Usually, the water heater or the pilot burner in the instant water heater will only get activated when the water pressure is above the specified activation pressure. The feature is provided to prevent any energy wastage when there is no water flowing in the heater – making the water heater energy efficiency.

Due to water shortage, the water pressure may be low or there may be a plumbing problem. Usually, it will take more time to fill the water when the water pressure is low. Fixing the problem with the water supply can increase the water pressure to the desired level.

Dirty Water Inlet Filter


The quality of water that flows through a water heater varies depending on the source. In many cases, people are using well water or groundwater, which has solids dissolved or suspended particles. The water heater will have an inlet filter to remove the dirt from the inlet water. Since this could affect the performance of other components of the instant water heater, it could lead to the water heater being faulty – one of the signs that your water heater is faulty is if it makes noise.

After the water heater is used for a few months or years, the filter could become clogged with dirt. Hence, there will be a hindrance when the water is entering the filter. Cleaning the filter periodically can fix the problem.


Mixing Valve Issues


Typically, the user can adjust the temperature of the water he uses by changing the setting of the mixing valve, which mixes cold and hot water depending on the preset temperature. In some cases, the valve or water heater may have issues despite setting the temperature. The water may not be mixed in the right proportion, due to which the desired temperature is not reached. A plumber should be contacted to troubleshoot to fix the problem with the mixing valve.

Clogged Heat Exchanger

Over time the heat exchanger may become clogged with minerals, reducing the water flow to a great extent which can result in water temperature fluctuations. Hence, it is advisable to clean the heat exchanger regularly to remove the sediments and deposits inside. The water heater manufacturer will provide guidelines for unclogging the heat exchanger.


The reasons why your water heater’s temperature is inconsistent can be due to factors such as low water pressure, dirty inlet filter, mixing valve issues, and clogged heat exchanger. Knowing these can help you to understand if you need to hire a professional to repair or replace your water heater.

Water Heater City Singapore is your trusted partner for comprehensive water heater services. With over a decade of experience, we pride ourselves on being a reliable water heater company. Our services such as water heater installation/replacement including instant water heater services installation and storage water heater installations are done efficiently by our expert team. Moreover, we will ensure your storage water heaters are Licensed Installation with PUB Submission and all works comply with standards prescribed/stipulated by PUB. If required, we are also able to open a false ceiling, patch it back up, and paint it to restore it to its original condition. 

We supply a wide selection of water heaters from top brands like Ariston, Rheem, Joven, 707, Rubine, and Champs. With a proven track record of successful past projects and a number of positive customer reviews on Google and Facebook, we ensure every service we provide will be done efficiently and with the utmost attention to detail. Contact us on WhatsApp at +65 8241 0032 for transparent quotations and honest pricing for all your water heater needs!