A digital psychrometer is essentially the type of hygrometer. It’s the tool that is used to measure relative humidity. However, both of them are different in terms of how it works. The psychrometer does measure relative humidity by utilizing two thermometers called dry bulb and wet bulb.
There are three types of psychrometer: Analog, Sling, and Digital. But today’s most commonly used are the digital type. It provides greater benefits surely. It’s more portable, easy to carry around, fast reading, and better accuracy.
Many jobs take advantage of this digital psychrometer such as HVAC engineers. If you are an HVAC professional and want to purchase a new one, then we have several options you could take a look at on this page.
In this chance, we share with you our top 10 picks best digital psychrometer through the following list. We cover them from the most entry-level to the most high-end one. Perhaps, it’s similar to from the most affordable to the most expensive one.
Top 10 Best Digital Psychrometer Reviews 2024
| Products | Pictures | Description | Price |
|---|---|---|---|
| 1. Preciva |  | - Great to use for room relative humidity | Price! |
| 2. Cooper-Atkins |  | - Uses two probes | Price! |
| 3. Vlike |  | - Great to use for room relative humidity | Price! |
| 4. Fluke 971 |  | - Great to use for room relative humidity | Price! |
| 5. Extech 445580 |  | - Pocket size - Great to use for room relative humidity | Price! |
| 6. Fieldpiece PRH2 |  | - Pocket-size - Easy to carry | Price! |
| 7. Testo 0560 |  | - for HVAC - for room relative humidity - The reading is on smartphone | Price! |
| 8. UEi Test DTH35 |  | - for HVAC | Price! |
| 9. Fieldpiece SRH3 |  | - For HVAC - In-duct measurement | Price! |
| 10. Fieldpiece JL3RH |  | - For HVAC - In-duct measurement - Hands free | Price! |
1. Preciva Digital Psychrometer
The first digital psychrometer we recommend is from Preciva. This is ideal for open room measurements such as in the house, office, laboratory, planting field, factory, etc. If you have tools that are easy to rust, then monitoring the relative humidity of the room with this tool is ideal as well.
It’s easy and quick to read as the relative humidity reading is displayed clearly and largely on the screen. Even though we consider it as entry-level, it nicely provides other several important readings. It’s able to measure humidity meter, temperature meter, wet bulb temperature, and dewpoint temperature.
It comes with little buttons but they are actually very intuitive to use. The screen is equipped with a backlight so that you are able to use it in dim ambient light and in bright light as well. Don’t worry! It only needs a 9-volt battery to run all the systems properly.
Overall this Preciva digital psychrometer is a wise choice if you need the simple one and charges you only a small amount of money (totally affordable).
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2. Cooper-Atkins SRH77A-E Digital Psychrometer
Cooper Atkins SRH77A-E comes with two probes that you could use to measure the temperature in two areas at the same time. Meanwhile, they both will be the dry and wet bulb thermometers that you could use to measure the relative humidity in a certain area.
This is a great tool. It has a wide temperature range and an excellent warranty. It can handle temperatures from 40° to 300°F which is outstanding. And the warranty is 5 years for the tool and 1 year for the probe. You must consider this one.
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3. VLIKE Digital Psychrometer
From the design, we have easily recognized the purpose of this psychrometer. The probe is quite big. The Vlike digital psychrometer is suitable to use both for an indoor and outdoor room. However, it’s not recommended to use it for in-duct purposes.
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4. Fluke 971
Fluke is one of the popular brands in terms of measuring instruments. In this case, we include Fluke 971 as one digital psychrometer that deserves to get your attention.
Another relative humidity tester available is Fluke 971. At a glance, there is no much difference with Vlike above. It looks like aimed for room relative humidity measurement.
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5. Extech 445580 Pocket Size Psychrometer
Extech 445580 is a nice pocket-size digital psychrometer that will detect the humidity level in your room.
It’s a simple tool. Through its screen, it displays relative humidity (10-90%), ambient temperature (32-122°F), and minimum-maximum reading.
If you are buying a psychrometer for general purposes (not for professional works), this choice is suitable for that.
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6. Fieldpiece PRH2 Affordable Psychomotor
Fieldpiece PRH2 is a pocket type digital psychrometer that comes with a friendly price point. This tool is very easy to use, slim, and provides instant reading through the screen over the wet bulb, %RH, dew point, and dry bulb temperatures.
Due to the small 2-inch length probe, we classify this one as the entry-level model for duct inspection works. However, most importantly, it suffices to help you get the reading through the hole you have made.
It’s powered by an AA battery that you can easily get from the nearest electronic store. This power will let it last up to 100 hours of use. If you want to first try the digital psychrometer, this one suits you.
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7. Testo 605i Wireless Probe Psychrometer
Another great relative humidity measuring tool is this versatile Testo 0560 1605 605i psychrometer. It can be used to inspect duct and room relative humidity. What makes it set apart from the others is the wireless reading. There is no screen, the reading is presented on a Testo Smart Probes app by Bluetooth 4.0 connection.
You could read the dew point and wet bulb temperature there with 0.1 °F resolution. This one is accurate. If you matter accuracy, this one is the right pick.
Testo 605i is a battery-powered tool. It uses 3 units of AAA that will last for 350 hours of use. Make sure your smartphone has been enforced with at least iOS 8.3 or Android 4.3 specification to run the reading app.
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8. UEi Test Instruments DTH35 Digital Psychrometer
Another simple digital psychrometer that you could purchase is this DTH35 from UEi Test Instrument. The display is built-in along with the probe. It has a long probe that is designed for in-duct measurement. It’s a sign of a good choice to pick up for your HVAC job.
It’s important to know that this stuff comes with enthalpy reading. You know that it needs to calculator or spreadsheet to count it. Along with this digital psychrometer, you are served with some important readings such as temperature, relative humidity, wet bulb, dew point, and enthalpy.
Keep in mind that this instrument doesn’t need water again to measure. Also, it’s equipped with a backlight so it’s clear to read the reading in dim light.
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9. Fieldpiece SRH3 In-Duct Digital Psychrometer for HVAC
Fieldpiece SRH3 is a perfect digital psychrometer for an HVAC technician. It has a tiny probe to provide an accurate reading. The probe can be easily attached to the hole and let it there. Enjoy it with your hands-free.
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10. Fieldpiece JL3RH Psychrometer with Remote Data Logging
Fieldpiece JL3RH is the best high-end digital psychrometer on the list. It’s great to use for HVAC when dealing with duct inspection, etc.
The flexible 9.25 inch (23.5cm) long and 0.36 inch (0.9cm) diameter probe will allow you to easily insert this tool to the duct system. The nice thing is it can stick steadily on the place due to the magnetic slide. So, your hands are totally free.
Aside from that, you could leave it alone to finish another job because it’s accessible through an app. Get the remote reading even up to 350 feet distance through the “Fieldpiece Job Link” app that is easily downloadable. Ensure that your smartphone meets the specification since it only works at least on iOS 7 and Android 5. On the app, you could access the parameters as below:
- Dry bulb
- Wet-bulb
- %RH
- Dew point
- Enthalpy
What is Relative Humidity?
Relative humidity (RH) is a term to describe the percentage of moisture content/water pavor in the air; as we know that air contains water vapor, nitrogen, oxygen, carbon dioxide, argon, etc [Source: Nasa.gov]. Water from lake, river, etc evaporates into the air, the air then contains water in the shape of gas.
Since it’s expressed in percentage, the relative humidity range is from 0% to 100%.
When the relative humidity is 0%, it means the air is highly dry. An example of this situation is the sky without clouds. It’s predicted rain will not happen. Conversely, when the relative humidity is 100%, it means the air is saturated with moisture. If it’s saturated further, rain can occur.
The temperature when the relative humidity reaches 100% is called the “dew point”.
Keep in mind that the term RELATIVE means it’s relative to the temperature. Suppose that the amount of moisture (gram) doesn’t change in a certain volume, its relative humidity in the temperature of 40°F will be different from in the temperature of 60°F. For example, RH is 100% when it’s 40°F. But it can drop to be 80% when it’s 60°F.
That’s due to the air can contain more moisture when it’s hotter. Conversely, the air can contain less moisture when it’s cooler.
Perhaps, the following video will explain in better visualization of relative humidity.
In measuring instrument maintenance and calibration, relative humidity is a vital thing. It can the reason for corrosion. Temperature and relative humidity are taken into account when calibration a certain measuring instrument. In daily life, people will feel comfortable when the relative humidity is about 50-60%.
Sling Psychrometer
In the past before the popularity of digital psychrometer, people use sling psychrometer. It consists of two liquid thermometers: dry bulb thermometer and wet bulb thermometer. The dry bulb measures the air temperature, while the wet bulb measures the temperature generated from the evaporation of the wet cloth.
You have to swing the two thermometers several minutes before taking the reading of the dry bulb and wet bulb temperatures. The differential value between them is called depression. This depression value is important to determine the relative humidity and the dew point later on.
If you employ an analog psychrometer like the sling psychrometer, you cannot directly read the reading of the relative humidity. A chart of “Dry bulb temperature Vs Depression for Relative Humidity” is needed to determine the relative humidity value. The chart of “Dry bulb temperature vs Depression for Dew Point” is also required to decide the dew point temperature.
In contrast, a digital psychrometer will display the relative humidity without requires you to read the chart. The microcontroller inside will do the job for you. Aside from that, its sensor doesn’t require swinging. On the display, you will get the reading of some parameters such as ambient temperature, dew point temperature reading, RH, etc.
The existence of this instrument makes it easy to measure in-duct relative humidity. It’s simple and quick, no need to swing inside the duct system. Even further, a duct psychrometer has an extension probe that lets you do the measurements hands-free.
Conclusion
Choosing the best digital psychrometer is not an easy task. Since this tool is relatively expensive, picking up one of them should be done carefully to not waste your money. Aside from that, you also have to avoid the failed one. Here we have reviewed some of the best psychrometers on the market. But we narrow it to the digital type because it’s simple and compatible with any occasion.