Thermocouple for a gas water heater: how to check and replace on your own

click fraud protection

Modern gas water heaters and boilers are equipped with a variety of different sensors. This is an obvious point, given the fully automatic mode of operation of such equipment. With the help of sensors, various parameters of the system are analyzed, and the end result is the correct adjustment of the gas equipment to the appropriate operating mode.

One of the important technological sensors is a thermocouple for a gas column, which monitors changes in operating temperature. In this article, we will talk about the device and the principle of operation of the thermocouple, methods of testing the operability. We will also consider how you can replace this element with your own hands.

The content of the article:

  • The device and purpose of the thermocouple
    • Thermocouple design features
    • The principle of operation and purpose of the sensor
  • Checking the thermocouple of a home gas water heater
    • Stage # 1 - preparation for testing by the tester
    • Stage # 2 - visual inspection for defects
    • Stage # 3 - testing the performance of the sensor
  • instagram viewer
  • How to replace the temperature sensor?
  • Conclusions and useful video on the topic

The device and purpose of the thermocouple

Sensor elements, structurally representing a thermocouple, have found wide application not only in household appliances, but also in industrial equipment. Essentially, a thermocouple should be viewed as a thermoelectric converter.

Typically, such a transmitter is used to measure ambient temperature. In particular, if you study how a thermocouple works in a gas boiler design, it can be noted that thanks to such a sensor, the temperature of the gas flame is monitored (measured) burners.

Appearance of a classic thermocouple

Here, approximately, this is how a thermocouple looks externally, but not for all exclusively designs of gas columns. Certain pieces of equipment may be equipped with sensors of a different configuration

Thermocouple design features

The implementation of the thermocouple is not particularly difficult, but from a technological point of view, the manufacture of this element requires high accuracy and compliance with the characteristics of the components used.

Actually, the main components of the sensor are two metal elements with different physical properties.

These elements (wires) are soldered at the ends on one side, while the end pieces on the other side remain free - used to connect to the thermo-EMF converter and transfer the difference potentials.

Schematic representation of the principle of operation of a thermocouple

Schematic of a classic thermocouple: 1 - junction point (actually a control element); 2 - metal with one EMF value; 3 - metal with a different EMF value; 4 - voltmeter, with which you can take readings in millivolts when the sensor is heated

The principle of operation and purpose of the sensor

The thermoelectric effect (in other words, the Zebbeck effect) determines the principle of operation of the device under consideration. Conductors made of different metals connected at one point form a potential difference, taking into account the fact that different metals have a different thermo-EMF coefficient.

With regard to the gas column, the operation of the thermocouple provides combustion control and protection from possible gas contamination. When the burner of a gas boiler or water heater operates in active mode (throws out a flame), a thermocouple installed in the flame zone generates an electric current under heating. The current is sufficient to control the opening and holding of the gas valve.

Diagram of a gas column assembly with a thermocouple

Classic type diagram for gas columns, clearly showing the operation of the equipment: 1 - flame control sensor / thermocouple; 2 - relay providing thermal protection; 3 - solenoid valve mechanics

If the heating temperature drops sharply (extinguished flame of the burner), the value of the generated current also decreases, which leads to the closing of the gas valve. Accordingly, the gas supply to the system is blocked, which ensures the safe operation of the equipment.

If your gas valve on the gas column does not work, we recommend that you familiarize yourself with inspection and repair methods.

Checking the thermocouple of a home gas water heater

Long-term operation of a home gas water heater allows for such a moment when the thermocouple fails. In this case, it is necessary to check the functioning of the system and, accordingly, check the control sensor directly.

Of course, not all owners of gas equipment are able to do this kind of work. And from a safety point of view, the best solution would be to contact gas company to solve such a problem.

But at the same time, situations can be different, including the impossibility of contacting specialists for some reason. Then the only way out is to try to do the work with your own hands.

Column thermocouple

The picture shows one of the options for the installed thermocouple, which needs to be checked: 1 - directly hot area of ​​the sensor, most often amenable to destruction; 2 - fastening nut, which must be unscrewed for dismantling; The same nut can be used on the other end of the thermocouple

In this scenario, an inexperienced user in gas affairs is interested in how check the thermocouple on the gas boiler using a tester - a common electrical diagnostic tool and electronics. Let's try to reveal this technological moment in order to facilitate the task.

Stage # 1 - preparation for testing by the tester

To begin with, we recall that the tester is a measuring device - dial or digital, with which it is possible to measure:

  • resistance;
  • voltage value (alternating and direct);
  • current strength (alternating, direct).

The marked measured values ​​are a kind of basic. And also, modern testers are able to check a number of other parameters, for example, inductance or capacitance.

But taking into account the principle of operation of the thermocouple of a domestic gas boiler, the voltage measurement mode in the millivolt range is quite sufficient.

Checking a thermocouple with a tester

The procedure for testing a thermocouple using a measuring device and a simple heating element - a paraffin candle. As can be seen from the tester readings (25 mV), the flame control sensor of the gas burner is working properly.

In addition to the measuring device (tester), the adjuster will need another fairly simple tool - a heating source. It is better if such a source has the ability to emit an open flame. Therefore, the best option here would be to use a regular paraffin candle.

Stage # 2 - visual inspection for defects

The very procedure for testing the flame control sensor is simple. However, before proceeding with a hot test, it is recommended that you carefully examine the thermocouple visually from the outside.

When examining the area of ​​the seam and the descending rod, physical defects of the metal, including burnout areas, should not be visible on the surface.

Stage # 3 - testing the performance of the sensor

After completing the visual inspection, you can proceed directly to the hot check. For this, the junction area and the descending section of the thermocouple rod of the gas column is placed above the wick of the candle.

Next, a measuring device (tester) is connected to the terminal ends of the thermocouple, after which the candle is lit. The generated potential is observed on the working scale of the measuring device.

Checking the functionality of the thermocouple with a lighter

Basically, any suitable heating source, such as a household lighter, can be used to test the sensor's functionality. True, depending on the power of the heating source, the readings on the tester may be below normal or, conversely, above normal.

The absence of any electrical potential readings clearly indicates a sensor malfunction. In case of partial defects, the measuring device may show chaotic (unstable) readings of units of millivolts. If the geyser sensor is serviceable, a stable value equal to tens of millivolts (20-30 mV) is usually recorded on the device.

Moreover, as the thermocouple body is heated by the flame of a candle, the readings on the scale of the device slightly change upward. If the candle flame is extinguished, the tester readings will go to zero as the rod body and the junction area cool down. That's all, actually. With this development of events, the thermocouple, as it is completely serviceable, can be safely placed in the place of action.

How to replace the temperature sensor?

Most of the options for repairing (replacing) the thermocouple of a household gas water heater require the dismantling of this element from the equipment structure. Accordingly, a potential technician needs to be aware of how to remove and install the sensor. Consider how the replacement of a thermocouple is performed in a gas boiler and what is needed for this.

The toolkit is quite simple. Usually one or two open-end wrenches are required for a 14 (or 15) nut.

It is worth noting that, based on a specific boiler model, the size of the fastening nuts may differ, as well as the design of the thermocouple itself. On some models, the thermocouple is secured with screws.

Dismantling the thermocouple of the gas column

Dismantling the control sensor on the gas water heater for subsequent performance testing. Depending on the boiler model, the mounting options for the sensor may differ

Thus, the master needs to free the sensor from the mounting screws, after which the structure is removed and can be repaired or replaced with a new one. Installation of a new element is carried out in reverse order.

Are you having problems with your gas water heater thermocouple? In this case, we recommend that you familiarize yourself with repair and replacement manual.

Conclusions and useful video on the topic

The video below demonstrates the process of testing a thermocouple installed on one of the models of gas boilers.

The video material explains in detail how to shoot, check, change a significant component of the gas column, without which the equipment actually remains operational only in the uncontrolled mode, which is extremely dangerous for the end user:

Replacing the sensor with your own hands is possible. However, for this, the home craftsman must have locksmith skills, be able to use measuring instruments:

Thanks to the thermocouple, the ignition and heating process is automated, the degree of safety of operation of the gas water heater and boiler increases. The material considered makes it possible not only to fully assess the technological significance of the thermocouple device in the design gas-using equipment and understand the structural intricacies of home boilers, but also, if necessary, repair equipment do it yourself. At the same time, it is important to remember about the safety rules, and if you have doubts about your own abilities, it is better to turn to specialists.

Would you like to share your personal experience of checking the functionality of a thermocouple? Or do you have useful information on the topic of the article and would like to share your knowledge with other users? Write your comments, participate in discussions - the feedback form is located below.

How to choose a water-heater: what is better + top brands

How to choose a water-heater: what is better + top brandsWater Heaters And Boilers

Agree, nice when the tap is always flowing hot water, regardless of its filing municipal utility companies. disruptions problem will help solve the instantaneous water heater installation. But the ...

Read More
Boiler indirect heating: an apparatus and principle of operation

Boiler indirect heating: an apparatus and principle of operationWater Heaters And Boilers

In private homes, cottages, sports complexes and hotels often use indirect heating boiler - water heater operates without connection to the public water supply. This equipment handles large volumes...

Read More
Indirect heating boiler own hands: a device of homemade boiler

Indirect heating boiler own hands: a device of homemade boilerWater Heaters And Boilers

Availability of water supply with hot water - is part of the usual comfort for the modern home. However, not always possible to solve the problem of centralized communications to the suburban real ...

Read More
Instagram story viewer