pressure gauges with thermometer or separate thermometer what is better

Choosing between a manometer with an integrated thermometer and a separate thermometer in the heating system is a common dilemma, to which there is no universal answer. The correct decision primarily depends on the type of boiler, the available space for installation, and the specific requirements for monitoring operational parameters.

When is a combined thermomanometer worth choosing

An integrated solution that combines pressure and temperature measurement in one body is ideal for standard apartment heating and smaller home boilers, where space on the boiler panel is limited. These devices, such as axial thermomanometer 0°C - 120°C 0 - 6 bar, 63 mm, allow the technician to check both critical values at a glance without the need to install additional accessories. An advantage is the lower price per unit and the minimization of the number of open threads on the water manifold, which directly reduces the risk of liquid leakage.

This type of device is, however, not suitable for all situations, especially if you need high accuracy of temperature measurement separately from pressure. In the case of professional systems, where independent control of both parameters is required for fault diagnosis, integration into one body can be a source of errors, as mechanical pressure can affect the accuracy of the thermometer part or vice versa.

Advantages and disadvantages of separate devices

Separate installations offer maximum flexibility in selecting the range and type of measurement, which is crucial for specific applications. If you need a manometer with a range of 0 to 10 bar for higher systems, while the temperature will be around 80 °C, you can buy axial manometer 0 - 10 bar, 63 mm and add axial thermometer 0°C - 120°C, 100 mm with a larger diameter for better readability.

• Measurement independence: A failure in one part (e.g., clogging of a gas capillary) does not mean loss of data on the other value.
• Accuracy: Separate thermometers often have higher accuracy and resistance to vibrations than integrated versions.
• Mounting variability: You can place the thermometer even out of the reach of the manometer, for example directly into the heat accumulator.
• Disadvantage: Higher overall cost of two devices and the need for multiple holes in the pipe or panel.

Physical limitations and the influence of vibrations on accuracy

Heating systems are exposed to constant pressure changes and vibrations that arise during the start-up and shutdown of the pump or burner. In combined thermomanometers, these factors can interfere with each other, as the thermometer mechanism is often more sensitive to overpressure and shocks than the manometer's spring element itself. Therefore, in practice, it is recommended to use separate thermometers with capillary tubing for heavy industrial applications, which are isolated from vibrations.

For this reason, it is often better to use a quality separate manometer and thermometer with modern condensing boilers that operate in a variable combustion mode, so you can be sure that no value is distorted by mechanical transfer of vibrations through the common body of the device.

Practical examples from installation practice

In a standard apartment boiler room, one well-adjusted thermomanometer with a range of 0 to 6 bar is often sufficient to cover the system's needs. For older solid fuel boilers or heat pumps, where it is necessary to monitor the temperature of the return and supply pipes simultaneously with pressure, the installation of two separate devices is recommended. For example, axial manometer 0 - 6 bar, 63 mm is ideal for measuring pressure in the system, while a thermometer with a longer probe or capillary is mounted directly into the pipe.

One of our jobs involved diagnosing an unbalanced system, where the thermomanometer showed a stable value, but a separate thermometer revealed a sharp drop in temperature due to a clogged filter. If we had used only an integrated solution, the problem would have gone unnoticed, as the mechanism was stable under pressure, but the temperature sensor was affected by the flow.

Maintenance, calibration, and device lifespan

The lifespan and maintenance of combined devices are more complex, as when disassembling them, you must check the seals and calibration of both measuring elements at once. Separate thermometers often have a simpler construction and are cheaper to replace if only the thermometer part is damaged. In regular maintenance in professional heating, a strategy is often chosen where the manometer is calibrated once every two years, while the thermometer is replaced or checked separately as needed.

• Combined: Easier installation, but in case of failure, the whole unit must be replaced.
• Separate: Possibility of quick replacement of one sensor without affecting the other.
• Calibration: Separate devices allow independent verification of accuracy according to standards.
• Maintenance cost: In the long run, the separate solution often pays off more, as spare parts are cheaper.

What to choose for different types of boilers

The decision should be based on the type of boiler and its operating environment. For condensing boilers that operate in a wide range of temperatures and pressures, it is safer to use separate elements that will not influence each other due to their construction. On the contrary, for simple gas boilers in apartment buildings, where parameters are stable, a thermomanometer is fully sufficient and more economically advantageous. It is always important to observe the correct measurement range to avoid excessive wear of the spring.

Mounting points and their impact on flow characteristics

An additional opening for a separate thermometer can affect the hydraulic balance of the system, so a three-way valve or a T-piece with a specially shaped tip that minimizes turbulence is often used.

Possible calibration issues and thermal expansion effects

During long-term operation of combined instruments, different thermal expansion of internal spring and thermometer tube materials may occur, leading to gradual shifting of the zero point for both indicators simultaneously.

Frequently asked questions

Can I use a thermomanometer instead of two separate instruments?

Yes, if you have limited space on the boiler panel and do not require extremely high temperature measurement accuracy, a thermomanometer is a functional alternative.

What is the difference in accuracy between a thermomanometer and separate instruments?

Separate instruments usually have higher accuracy and are less affected by vibrations, which can distort measurements in integrated models.

Which type is more suitable for heat pumps?

For heat pumps, separate instruments are recommended due to the need for precise monitoring of temperature gradients, which are critical for their efficiency.

In conclusion, neither solution is automatically better - it depends on your specific needs and budget. If you are looking for simplicity and space saving, choose a thermomanometer. If maximum accuracy and maintenance flexibility are important to you, invest in separate instruments.

Do you have a question about this topic?

Not sure which option to choose or dealing with a specific situation in your home? Write to us - we are happy to help.