Hot water heater sensor failure [portable power guide]

What are the signs your hot water heater sensor is going out? The sensor controls the temperature in the heating circuit and water heater. The temperature sensor works on the same principle as a thermometer. If the water heater sensor failure occurs, the water in the heating circuit will be cold or lukewarm water.

The main causes of the malfunction

1.      The electronics burned out.

2.      The copper tube does not work: There is cold water in the circuit.

3.      The heating element turns on randomly.

4.      The device is not turning on.

Water heater indicators are visible on the panel. The water heater temperature sensor protects the device from overheating. If the temperature rises, the sensor is triggered.


The signal is sent to the function module, the water heater is switched off.

How to identify water heater problems

The temperature sensor sometimes breaks down. You can eliminate breakdowns yourself.

The main reasons

1.      The heating element does not work: it is necessary to clean the heating element, replace the magnesium anode and check gas control knob.

2. The faulty temperature heat sensor is broken. To check this fact is simple: it is necessary to test the sensor resistance. If there are no changes in the device, you should buy a new device.

Inspecting the water heater’s temperature sensor

The water temperature setting is checking a tester. Before starting work, it is necessary to find the sensor resistance level in the technical passport. The NTC1/NTC2 temperature sensors and gas control valve also sometimes break down (there is no gas supply). Heat transfer surface also checking the tester.

How does a water heater sensor work?

The faulty temperature sensor disrupts the temperature balance. If the circuit is broken, there is no heating of the liquid. The sensor also protects the system: if the electric water heater warms the water too much, then a shutdown follows. Hot and cold connections depend on the intensity of the device.

A faulty sensor can cause a water heater to boil off. The principle of operation of the device is based on the deformation of metal plates that are bonded to each other.

Each of them has a coefficient of thermal expansion.

The plates touch, the circuit closes. Another useful property of the thermostat is the reduction of water heating costs and electricity consumption.

What are the signs of a temperature sensor failure on a hot water heater?

Malfunctions are associated with some of the factors:

•  mechanical disturbances

•        violation of hot and cold water connections

•        breakdown of electronic elements

•        disruption of gas shut-off valve

•        faulty sensor.

The main signs of block temperature sensor failure are:

1.      Water temperature is very low (or lack thereof).

2.      Arbitrary switching on and off.

3.      High tank temperature.

Insulate the water heater

Insulation plays an important role: it reduces heat losses. The hot water in the tank cools down much more slowly (up to 50% of the time), due to this energy is saved.

Wrap the water heater in an insulation

If the device has modern insulation, then heat losses are reduced to 45.5%. The amount of electricity for making hot water is reduced to 20%.

Hot water heater sensor failure

Special markings are installed on individual panels. Before starting the operation, it is necessary to carefully read the technical data sheet: Operating rules.

How do you know your Honeywell water heater temperature sensor is going out?

There are several reasons: why the water heater sensor stops working.

The most common reason is a violation of contact.

A breakdown of the sensor leads to heating up a water tank. The water heater’s efficiency declined, and also it can provoke a short circuit.

What does the status light mean on a water heater?

Modern boilers are equipped with light indicators. It’s displaying functionality. If the light bulb starts to flicker (or stops glowing). Thus, the technique warns that there are problems in the work. If there is a similar case, then you need to contact the service repair service.

Too hot water

One of the clearest signs that the sensor will soon break: is when the hot water gets too much to the desired temperature. If this happens regularly, it is better to contact the water heater maintenance (repair service).

Functioning gas control valve

The gas valve of the boiler is created from two coils:

1. Locking.

2. Modulating.

If 220 volts are supplied to the locking gas valve, then a minimum of gas supply is required. The gas flow consumption is regulated. The new gas valve work is interconnected. If an electric pulse does not come, the sensor is faulty. In this case, there is a malfunction in the gas valve.

How to power the Honeywell water heater?

The sensor is subjected to various loads during operation. The failure of this important element is a phenomenon that occurs quite often. Sometimes, it is necessary to install a new sensor. To perform such an operation, it is required:

1.      Test the gas control valve.

2.      Remove the thermostat and heaters.

3.      Turn off the heat pump for 6-10 seconds.

4.      Wait for the excess heat to leave the heater.

5.      Turn on the indicator.

6.      Check burner assembly manifold cover.

7.      Set the function button pilot light.

8.      Making burner assembly.

Is the blinking water heater light dangerous?

The LED indicator is installed by the manufacturers to show the operating mode of the device. If there are problems in the system, the indicator starts flashing (or signal switch) – it is maybe a malfunction warning.

What to do if a water heater sensor fails?

The sensor sometimes fails. The main task of this element is to control the water heater temperature in the tank. If the sensor breaks, then it is necessary to do the following:

1. The cord is pulled out of the socket.

2. Wait for hot water pipes to cool down.

3. Check test gas control valve.

4. Test the wiring using the device.

How to replace the Honeywell water heater temperature sensor?

To dismantle the old device and install a new one, you will need to take some actions:

1.      Turn off the equipment.

2.      Block the water supply.

3.      Тank drains the water.

4.      Remove the water heater.

5.      Checkthe gas valve, the gas supply.

The thermostat is located at the bottom: the wiring is disconnected, and the sensor is removed.

Take all the necessary actions and use the tools:

·         screwdrivers

·         wrench

·         tester with pin probes

If there is no spark plug in the device, then it is disconnected using a 7/8-inch wrench.

ow to test your Honeywell water heater sensor?

To understand the condition of the heater sensor, it is necessary to use a tester: a multimeter.

Hot water heater sensor failure

The standard operation is done according to the algorithm:

1. The multimeter with pin probes is set to the mode: Resistance measurement.

2. The probes are applied to the contacts.

3. If there is no resistance reading on the scoreboard, then the element must be changed.

If resistance is present, then an operation is performed:

1. The multimeter is set to the value: minimum.

2. The thermostat tube warms up with a lighter.

3. The arrow on the multimeter should move.

The conclusion can be unambiguous: there is resistance reading good, which means: the protective relay is working.

Other options are also possible:

1. The gas valve is disassembled.

2. The tester is installed on the front control panel.

3. The probes are attached to the connector pin.

Such actions allow you to safely check the operation of contacts. Blocking is completely excluded in this case.

How to improve water heater’s efficiency

To extend the service life of the device, it is necessary to operate following the recommendations.

It is also necessary to regularly carry out a technical inspection of the heater.

It is recommended to pay attention to different temperatures during the operation.

Drain the water tank and wash out the sediment

Precipitation inevitably occurs during the operation of the heater. Sediment over time can cause a malfunction of the device, and its efficiency decreases.

For example, the thermometer begins to show the unreal water temperature in the tank.

The sediment also provokes too much consumption of electrical energy.

To clear the tank of sediment, it is required to:

1.      Disconnect from the electrical network.

2.      Drain the water from the center hole of the tank.

3.      Carry out cleaning.

Functions of thermocouple in water heater

A thermocouple is installed inside the gas water heater. This element is designed to automate the switching on and off of the heater.


The water temperature level at which the heater stops working is set on the adjusting thermostat. This unit is mounted at the bottom. The heater temperature sensor attached hard must be checked periodically. A multimeter is used for this.

What to do if replacing the sensor doesn’t work?

When replacing the thermostat, check the heating defective sensor. If the new device does not work, it is better to seek advice from a specialist.


How do you reset the temperature sensor on a hot water heater?

There is a red reset button on the back panel (it is located next to thermostats or behind metal panels). You need to press and release the button, then pilot light is turning on.

What does temperature sensor failure mean?

If the sensor does not work correctly, it leads to too much loss of electrical energy. The temperature relay, which is responsible for working the water heater, can also break. As a result of such failures, incorrect information enters the digital chip, and this can provoke heater temperature sensor failure, violation of the entire system.

What does a water heater sensor do?

The water heater temperature sensor controls and protects the system. If the water temperature is too high, the sensor turns off the heating.


The hot water heater sensor failure can be repaired by yourself. Sometimes it is necessary to consult a specialist about heater temperature sensor failure.

Robert Brooks

I have an engineering background. I have my own house, where I live with my wife and children. I want to say that the most important thing when equipping a house is to choose the right heating, ventilation, and air conditioning systems.

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