Digital Thermo-Hygrometers

Quick Answer: A digital thermo-hygrometer is a small electronic instrument that displays air temperature and relative humidity on one screen, used to keep watch on rooms, stores and cabinets where both matter. This listing is the plain model in the range; its display, ranges and any extra functions are confirmed on request.

Reading Temperature and Humidity Together

Relative humidity is the amount of water vapour in the air compared with the most the air could hold at its current temperature. Because warm air can hold more water, the same air shows a lower relative humidity when it is heated and a higher one when it cools. That is why a thermo-hygrometer shows both values: a humidity reading means little without the temperature beside it.

In a laboratory the combination matters in several places. Microscopes and other optical instruments kept in damp rooms grow fungus on their lenses; hygroscopic chemicals such as calcium chloride and sodium hydroxide absorb water in humid stores; analytical balances drift when humidity changes; and herbarium sheets, seeds and paper records deteriorate in damp air. A digital thermo-hygrometer on the wall or shelf shows when the room needs ventilating, dehumidifying or heating.

Place it at the height of what you are protecting, out of direct sun and away from heaters, air-conditioning outlets and outside doors, and give it several minutes to settle after moving it. Humidity sensors drift slowly with age, so compare the reading occasionally with a whirling hygrometer.

Applications

• Watching humidity in microscope and optical instrument rooms to prevent lens fungus
• Monitoring chemical stores that hold hygroscopic or moisture-sensitive substances
• Keeping records for balance rooms, where humidity changes disturb weighing
• Classroom weather and comfort observations in geography and science lessons

Specifications

Care & Handling

• Keep the sensor vents clear of dust and never spray cleaner onto them.
• Allow several minutes for the reading to settle after moving the unit between rooms.
• Avoid places where condensation can form on the unit, such as a cold store doorway.
• Replace the battery before it runs flat, as low voltage can make displays unreliable.

Why Choose LabEquip

Schools, colleges, pharmacies and museums buy simple thermo-hygrometers for every room and store where damp or heat can damage stock. LabEquip offers this plain model in its General Lab Products range, with an Advanced version for users who need more functions; contact LabEquip for quantities.

Frequently Asked Questions

Why does humidity go down when the room heats up?

Relative humidity compares the water vapour present with what the air could hold. Warm air can hold more, so heating the same air lowers its relative humidity even though no water has been removed.

What humidity is suitable for a microscope room?

Drier is better for optics, because fungus grows on lenses in persistently damp conditions. Many labs keep instrument rooms dry with ventilation or a dehumidifier; follow the instrument maker’s storage guidance.

How accurate is a digital humidity reading?

Electronic humidity sensors are less accurate than temperature sensors and drift slowly with age. For important records, compare the reading from time to time with a whirling hygrometer.

Where should I place the thermo-hygrometer?

At the height of what you are protecting, away from direct sun, heaters, air-conditioning outlets and outside doors. Readings near these spots do not represent the room.

What is the difference between this and the Advanced model?

This is the plain model, which displays temperature and humidity. The Advanced model is listed separately for users who need more functions; which functions each has is confirmed when you enquire.

Can the unit be used outdoors?

It is designed for indoor air. Rain, direct sun and condensation damage humidity sensors and give false readings; for outdoor temperatures, use the IN-OUT model with its separate outside sensor or a sheltered weather screen.

Last Updated: September 2026