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Ear Thermometer

How do ear thermometers work?

The ear drum shares its blood supply with the temperature control center of the brain, so changes in body temperature are reflected sooner and more accurately in the ear than in other places.

In addition, the ear drum is not affected by breathing, sweat, diet and other factors. It is the best indicator
of body temperature.

°C / °F Switch

In “Power Off” mode, press and hold the “SCAN” button, then press the “ON/MEM” button for 3-5 seconds, icon “°C” will be switched to icon “°F”. You can also use the same process to change the LCD display from °F to °C.

How to install the probe cover?

Please follow the instructions below.

Probe Cover Installation Video
(1)  Place a new probe cover on the connection ring. (See Figure 1)
NOTE Make sure to place the “Adhesive Side” of probe cover “Upward.”
(2)  Align the probe with the center of probe cover. Insert the probe into the probe cover on the connection ring. (See Figure 2)
(3)  Push the connection ring until the “Click” sound. This means the probe cover has been installed successfully.
NOTE The probe cover detector is optional. If the probe cover did not connect firmly, the “” icon will flash on the LCD screen.
  Please check the setting of probe cover again.
Figure 1   Figure 2

* WarningKeep the probe covers and connection ring away from children.

Why is my measurement too low or high?

You may check by following items:

Ear Canal:   Earwax might block the infrared measure accuracy.
Probe Cover:   The most popular situation is the probe stuck with earwax that blocked infrared transmission and lower the measurement. If you bought a probe cover model, we recommend user to change probe cover each time to avoid cross contamination.
Note:   If you bought a probe cover model, the probe cover may break and affect the accuracy after using for several times or receive external hit. We recommend user to check probe cover's integrity before every measurement. If the probe cover is broken, please change a new one.
Lens:   If you bought a probe cover model, the most common situation is user measure without installing probe cover. The probe lens is stuck with earwax and lower the measurement. If the lens is dirty, please follow the manual's instruction to clean lens with cotton swab.
Note:   User hit the thermometer carelessly might cause the probe lens damage. Please return full package to retailer for service if there is damage.

How to get a precise measurement?

Check the five steps to get the best measurement:

 STEP 1 : Is the ambient temperature stable?
 STEP 2 : If you bought a probe cover model, is the probe cover a new one?
 STEP 3 : Is ear canal clear without earwax?
 STEP 4 : Is the ear canal straight during the measurement?
 STEP 5 : Did you take out thermometer after “Beep” sound?

May I reuse the probe cover?
If you bought a probe cover model, in order to avoid cross contamination, we recommend user to change probe cover after each measurement. Also, check the probe cover is in good shape and the ear canal is clear without earwax.

Why do I get different temperature for continuous measurement? Sometimes in normal, sometimes in lower, sometimes in higher temperature.

The user and thermometer need to adapt to ambient temperature. The rapid temperature change may cause the inaccurate measurement.

Before the measurement, please stay in a stable environment for 5 minutes and avoid exercise, bath for 30mins.

We recommend user to place thermometer indoor for 15 minutes to adapt to temperature and get the correct measurement.

How to open the battery cover to replace battery?

Please use the incisive tool, for example: Pen tip…And so on. Inserts on battery cover's safely vent,
under the effort presses, simultaneously uses the thumb downward to shove open the battery cover,
then replaces the battery.

(Battery installation picture take TH809 for example. For other models, please refer to the user's manual.)

How do I have my ear thermometer repaired?

Please send the complete device to the nearest retailer for service.

I lost my ear thermometer's manual.

Don't worry. RADIANT INNOVATION provides consumer online thermometer manuals to download.

My temperature measured in the right ear is different from that measured in left ear?

The ear canal of both ears is not totally the same. Some people can get same temperature but most people could get 0.5 ~ 1.0 ° C different temperatures. It is recommended that you measure 3 times with the same ear. If the 3 measurements are different, select the highest temperature.

The measurement in air conditioning room is different from that in non- air conditioning room?

When ear thermometer is under rapid temperature change, we recommend user to place thermometer for 15 minutes to adapt to temperature and get the right temperature.

Does forehead mode need to touch body?

Infrared Forehead Thermometer-TH0XF, TH2XF series
Multi-function Thermometer (Forehead Mode)
Please measure close to “the temples” about 0.5 cm distance.

Non-contact Forehead Thermometer-TH30F
Hold the thermometer 1 to 3 cm from “the central forehead”.

Although the thermometer does not touch body, please also follow the instruction for clean and storage to keep accuracy.

What is the normal body temperature?

A normal range for body temperature is 35.8°C ~ 38.0°C (96.4°F ~ 100.4°F). Each person has different temperature, please contact qualified doctor for details.

Here are the normal body temperatures for reference:

Ear Temperature: 35.7°C ~ 37.5°C
Rectal temperature: 35.7°C ~ 37.5°C
Oral temperature: 35.5°C ~ 37.5°C
Armpit temperature: 34.7°C ~ 37.3°C

Body temperature variations affected by age:

0 ~ 2 years: 36.4°C ~ 38.0°C
3 ~ 10 years: 36.1°C ~ 37.8°C
11 ~ 65 years: 35.9°C ~ 37.6°C
  > 65 years: 35.8°C ~ 37.5°C


1. Chamberlain, J.M., Terndrup, T.E., New Light on Ear Thermometer Readings, Contemporary Pediatrics, March 1994.
2. Chamberlain, J.M., et al., Determination of Normal Ear Temperature with an Infrared Emission Detection Thermometer, Annals of Emergency Medicine, January 1995.

What is the standard for fever?

Different site in the body and different thermometers may get different temperatures.
Recommended fever standards stated below:

Site Fever Standard Measuring Time
Oral 37.5 °C 1 min. half - 2 min.
Forehead 37.5 °C Several seconds
Ear 38.0 °C Several seconds
Axillary 37.0 °C 3 min.
Rectal 38.0 °C 1 min. - 1 min. half

Source: Centers for Disease Control , R.O.C.(Taiwan)

The baby’s ear canal is too small to insert the probe. How do I measure the temperature?
Don’t worry. You can pull the baby’s ear straight back to make sure the ear canal is straight. Make the probe lens face to the ear drum and get the temperature.


For children under 2 years old, pull the ear straight back.
For adults and children over 2 years old, pull the ear up and back.
0-2 years >2 years  

Does ear thermometer need to maintain regularly?

Ear thermometer is a health care product that needs maintenance, you could use soft cloth to wipe the appearance. Never use benzene for cleaning and never submerge thermometer into water or any liquids. Probe lens is the most delicate part of thermometer, please use cotton swab with alcohol (70%) to wipe it.

Follow the below instruction and video to clean the probe lens.

Probe Lens Cleaning Video

1. Before using the cotton swap with 70% alcohol to wipe the lens, slightly flip the cotton swab to cut down the spare alcohol.
2. If there is no 70% alcohol, use alcohol prep pad to soak the cotton swab.

Important: Do not use sharp pointed object to wipe the lens.

Does summer and winter ambient temperature affect the measurement?

RADIANT INNOVATION ear thermometer compares ambient temperature and makes compensation. The measurement between 10°C~40°C (50°F~104°F) is the same, but the human body changes a little in different season and different environment. For example, the body temperature becomes hotter after exercise and hot shower.

Is the ear temperature more precise than oral temperature?

The ear canal of both ears is not totally the same. Some people can get same temperature but most people get 0.5 ~ 1.0 ° C different temperatures. RADIANT INNOVATION consider the 0.4°C inaccuracy is due to the sensor did not completely receive the ear's infrared. Basically, when the self diagnosis function is normal, the different temperature is affected by the measuring probe's location. It is recommended that you measure 3 times with the same ear. If the 3 measurements are different, select the highest temperature.

Why do I have to wait for 6 seconds during constantly measurement?

Wait 6 seconds is to reduce the thermal shock effect result from probe of thermometer contact with ear channel, and hence reduce the chance to affect the accuracy.

Can I measure without probe cover?

If you bought a probe cover model, we recommend user to install probe cover before measurement base on hygienic principal. A thermometer measurement without probe cover might cause 1° C inaccuracy.

The measurement only takes 1 second?

Yes, it's real. The infrared thermometer sensor could easily receive the infrared ray sent out from human body. RADIANT INNOVATION ear thermometer breaks the old measure style about how long and which part. Just put ear thermometer into the ear canal and press SCAN button for 1 second to get temperature. From now on, parents could easily get your excited baby's body temperature without breaking the mercurial thermometer.

Is the thermometer waterproof?
Be careful! The thermometer is not waterproof. Please do not submerge in any liquid and avoid the direct sunlight over 10°C to 40°C (50°F to 104°F) environment.

How long do I have to change thermometer's battery?

RADIANT INNOVATION thermometer uses a lithium battery (CR2032). Battery life is estimated at 3,000 readings. Enable normal use: 1 year.
The battery life depends on the frequency you use. Please change a new battery when the LCD battery icon flashing.

Does the ear thermometer I bought only measure ear temperature?

General professional ear thermometers only measure ear temperature. RADIANT INNOVATION ear thermometer is designed for ear temperature measurement.

Can I measure under sunlight?

The ultraviolet ray in sunlight will damage the ear thermometer, we recommend user to measure indoor.

Does ear thermometer radiate infrared?

The ear thermometer receives the ear drum's infrared and switch to body temperature; therefore, it does not radiate infrared.

Do I have to lie down while I use ear thermometer?

You don't need to lie down. You may use at any place, any time, even when you are boarding.

Radiant Innovation Inc. was established in year 2000 and mainly focus on Infrared Technology. Our RD, QA, Manufacture Team have been in this field for more than 20 years. Therefore, we are able to provide high-quality & good-design products to all of our customers in the world. There are three product-lines in Radiant in the moment.

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