Tankless Water Heater Too Hot! What to Do?

Tankless water heaters are efficient devices, but sometimes they can produce water that’s excessively hot. This issue can arise even in the lowest setting, causing discomfort and potential safety concerns.

Many RV owners and users of brands like Girard and Fogatti have reported their tankless water heaters getting too hot. Furrion tankless water heater users have also noted instances of their units overheating. So, why is this happening? There are several reasons behind this phenomenon.

A tankless water heater might overheat if it doesn’t have enough cold water to absorb the heat it produces. This imbalance can lead to water temperatures that are uncomfortably high.

Another potential reason is a broken flow sensor, which can cause the heater to alternate between hot and cold water. This inconsistency can be both annoying and potentially harmful.

Checking the thermostat is a good starting point. Be sure that the tankless water heater’s thermostat is turned down to its lowest setting. If the water is still too hot, it’s possible that the unit’s temperature is set too high.

Adjusting this can help regulate the water temperature and prevent it from becoming too hot. If these solutions don’t work, consulting a professional is advised to ensure safety and proper functionality.

Read More: Best Propane Instant Hot Water Heaters

why is Your tankless water heater too hot?

Tankless water heaters are renowned for their efficiency and convenience. Yet, like all appliances, they can face issues. Here are some common reasons for tankless water heaters running too hot and their respective solutions:

1. Insufficient Cold Water Flow

Tankless water heaters rely on a balance of hot and cold water. If there’s a reduced flow of cold water, the heater can produce water that’s too hot.

Solution: Regularly check the cold water inlet for any blockages or obstructions. Ensure that the water supply valve is fully open. If the issue persists, consider installing a water softener to prevent mineral buildup which can restrict water flow.

2. Faulty Flow Sensor

The flow sensor monitors the amount of water passing through the unit and adjusts the burner accordingly. A malfunctioning sensor can misread the flow rate, causing the heater to overheat.

Solution: Inspect the flow sensor for any signs of damage or wear. Clean it regularly to ensure it’s free from debris. If the sensor is faulty, replace it with a new one.

3. High-Temperature Setting

Sometimes, the unit’s default or set temperature might be too high for your needs.

Solution: Access the heater’s control panel and adjust the temperature to a more suitable level. Regularly monitor the set temperature, especially after power outages or resets.

4. Malfunctioning Thermostat

A thermostat that’s not reading temperatures accurately can cause the water to become too hot.

Solution: Test the thermostat by comparing its readings with an external thermometer. If there’s a significant discrepancy, it might be time to replace the thermostat.

5. Scale Buildup

Over time, minerals in the water can accumulate inside the heater, affecting its performance and causing it to overheat.

Solution: Perform regular descaling procedures using a suitable descaling solution. If you live in an area with hard water, consider using a water softener to reduce mineral buildup.

6. Damaged Heat Exchanger

The heat exchanger is crucial for heating the water. If it’s damaged, it can cause the water to overheat.

Solution: Inspect the heat exchanger for any signs of damage or wear. If it’s compromised, it’s best to replace it. Regular maintenance can also prolong its lifespan.

Tankless Water Heater Overheating: Preventive Measures

Tankless water heaters are a popular choice for many homeowners due to their efficiency and space-saving design. Yet, like all appliances, they can sometimes run into issues, one of which is overheating. Here are some preventive actions to ensure your tankless water heater doesn’t get too hot:

Regular Maintenance: Scheduling regular maintenance checks can help identify potential problems before they escalate. This includes checking for mineral buildup, inspecting the heat exchanger, and ensuring the flow sensor is functioning correctly.

Adjust Temperature Settings: Ensure the temperature settings are not set too high. A moderate setting can prevent overheating and still provide comfortably warm water.

Install a Water Softener: Hard water can lead to mineral buildup inside the heater, affecting its performance. A water softener can help reduce this buildup, ensuring smoother operation.

Monitor Water Flow: Ensure there’s a consistent flow of cold water. Any obstructions or blockages can affect the balance of hot and cold water, leading to overheating.

Check for External Factors: Ensure the heater is not exposed to direct sunlight or placed near heat-emitting appliances. External heat sources can cause the unit to overheat.

Learn More: Symptoms, Causes, and Replacement of a Bad Thermocouple in a Water Heater

Some Common Questions and Answers on Tankless Water Heater Overheating

1. Can external weather conditions affect my tankless water heater’s performance?

Yes, extremely cold or hot weather can impact the efficiency and performance of the heater. It’s advisable to protect the unit from direct sunlight and freezing temperatures.

2. How often should I descale my tankless water heater?

Descaling frequency depends on water hardness. In areas with hard water, descaling every 6-12 months is recommended. In softer water regions, once a year should suffice.

3. Are there any visual signs of an overheating tankless water heater?

Yes, discoloration or warping of the outer casing can indicate overheating. If you notice these signs, seek professional assistance.

4. Can an old unit be more prone to overheating?

Age can impact performance. Older units might not have the latest safety features or might have wear and tear, making them more susceptible to overheating.

5. Does the size of the heater affect its tendency to overheat?

Yes, a unit that’s too small for the household’s needs might work harder and overheat. It’s crucial to choose the right size for your requirements.

6. Can a faulty installation lead to overheating?

Improper installation can impact the unit’s efficiency and lead to issues like overheating. Always ensure a professional installs the heater.

7. Are there any alarms or indicators for overheating in modern units?

Many modern tankless water heaters come with safety features, including alarms or indicators that alert users to potential overheating. Always refer to the user manual for specific features.