HomeInOn – Hygrometers for home or shop
Also known as a humidity meter, humidity gauge and hydro-thermometer, a hygrometer is a device for measuring humidity – the amount of water vapor in the air.
Humidity levels are generally expressed as relative humidity (RH), a ratio of the amount of water vapor in the air and the maximum amount of vapor the air can potentially hold at a given temperature. The range is from 0% (bone dry) to 100% (soaking wet).
Why would I need one?
Too much humidity in your home or workshop can be just as harmful as too little. In Canada, humidity levels are typically higher in the summer and lower in the winter. You’ve probably noticed that when you start to heat your home in the winter the indoor air gets noticeably dryer. If you have carpeted or laminate floors you may get occasional static shocks. Low humidity levels can also cause scratchy throats, itchy eyes, dehydrated skin, nosebleeds and the like. If you have eczema or acne, you’re likely to experience more frequent flare-ups. It can also cause cracking, splitting and bending in wood furniture, trim work and flooring.
When the humidity level gets too high mould and mildew can start to grow, which can exacerbate respiratory conditions like asthma and bronchitis and skin conditions like eczema. High humidity can also cause paint to flake, wallpaper to discolour or curl, wood floors and trim to warp, and wood drawers and doors to stick.
Most research studies concur that the ideal RH range for your health and comfort is between 30% and 50%. While you can guesstimate what the RH level is, the more accurate and easy way to know is with a hygrometer.
Two Basic Types
The two most common types of hygrometers are analog and digital. Most analog hygrometers use some kind of composite coil – typically a thin metal strip bonded to a paper polymer – that contracts and expands with changes in humidity. Digital hygrometers, which use resistive or capacitive sensors, are much more accurate. Some enable you to take readings remotely via Bluetooth or Wi-Fi with a mobile device, and can integrate multiple sensors that you place around the house, inside and out. There are hundreds of different hygrometer models on the market with a wide range of features and price points. Here are three examples of digital hygrometers. As you can see in the main photos, humidity readings vary slightly (from 46.8% to 50%), while temperature readings are much more consistent (26° to 26.5°).
AcuRite Weather Forecaster with Wireless Charging Pad
#01193M, $54.99 US plus $33.10 shipping, Acurite.com
This AC-powered model comes with a base unit and an indoor/outdoor remote transmitter. The transmitter has a 165-foot range. The base unit features a large dimmable LCD display and a Qi-charging pad. Any Qi-equipped phone or headphones that you place on the pad will be charged in about three hours. It also has an alarm clock with snooze button so you not only wake up to a fully charged phone but with up-to-the minute humidity and temperature readings. It has a humidity accuracy of +/- 3% to 5%, depending on the RH level.
Extech Multi-Channel Wireless Hygro-Thermometer
#RH200W, $119 CAD, Extech.com
This battery-operated model consists of a base unit that displays oversized digits and an indoor/outdoor transmitter with a 98-foot range. It can be connected to up to eight transmitters. The LCD display has a handy auto-night light. Trend arrows on the display indicate changes in humidity and temperature readings, while icons notify you if conditions are too cold, too hot or humid, or within the comfort zone. It also displays maximum and minimum humidity and temperature readings. It has an accuracy of +/- 5%.
SensorPush Wireless Thermometer & Hygrometer
from $65.99 CAD, SensorPush.com
If a high level of accuracy and wireless connectivity is your cup of tea, this US-made model is a good choice. The tiny (1.57″ x 1.57″ x .65″) sensor is powered by a CR2477 coin cell battery that delivers about two years of runtime. It offers Bluetooth connectivity and has a 325-foot line-of-sight range. There’s an optional Wi-Fi gateway that enables you to monitor the sensor remotely from anywhere via the internet. The SensorPush takes readings every minute and can store up to 45 days of data internally (HT.w model) and an unlimited amount of data via the free SensorPush app. The app can manage an unlimited number of sensors. The HT1 has a humidity accuracy of ±4.5% while the HTP.xw has an accuracy of ±2.0% and also measures barometric pressure.
Basic No-Frills Analog
Analog hygrometers cost between $5 and $20. While inexpensive, they are inaccurate; expect upwards of a 10% variation from actual humidity levels. However, they are useful if all you want to know is whether the humidity level in your home is roughly within the optimum range (30% to 50%). Those that include a thermometer give a much more reliable reading. Home Hardware Indoor Thermometer & Hygrometer (#4470-156, $12.99, HomeHardware.ca)
Carl Duguay - [email protected]
Carl is a Victoria-based furniture maker and the web editor at Canadian Woodworking & Home Improvement.