What is Humidistat?

OK, now let’s cut through the clutter and get to something that could actually affect how you feel, how healthy you are and even how substantial your wallet feels: humidity. We’ve all been there, right? You know, that sticky, clammy sensation when the air’s too thick, or that dry, crackly feeling that makes your skin itch and your throat sore. You may be asking yourself, what is a humidistat and will it really solve these problems?

In its simplest terms, it’s a nifty device that measures and adjusts the humidity levels within your household air. Consider it the air’s thermostat, but rather than temperature, it’s humidity that is being controlled. It is the unsung hero beavering away in the background so that your home is not too wet and mouldy, nor too dry and dusty.

The Importance Of Humidity Control (And It’s Not Just Comfort)

I mean, living somewhere with whacky humidity is not just annoying, it’s a legit problem. Getting this right isn’t some highfalutin luxury; it is, instead, a basic cheat code for a more pleasant living environment. Here’s why you want to pay attention to the details:

Your Health: Breathe Easier, Live Better

If the humidity’s off, your body’s going to let you know.

• Too High (over 50-60% RH): Here’s where the folks you don’t like come out to play. I’m talking moulds, mildews, dust mites, bacteria and viruses. These can lead to respiratory problems, asthma, bronchitis and even nasty allergies. No one wants a home filled with airborne nasties.
• Too Low (less than 30% RH): Conversely, super-dry air is your skin’s worst nightmare, turning it flaky and itchy. Chap lips, dry nasal passages and an irritated throat are a thing of the past. And it can even leave you more susceptible to catching colds and other respiratory issues. Oh, and who can forget the static electricity that turns your hair into a science fair project every time you grab a doorknob.

Keeping the relative humidity between 30% and 50% (or, in warmer climates, up to 60%) is the sweet spot for human health. Some even cut it down to 40-45% for optimal comfort and health. It cuts down allergens and wards off those pesky winter bugs.

Providing you with The best barrier coverage: Bye Bye Warped Wood And Damaged Drywall

Your house’s bones — and your favorite things — aren’t so down with these humidity changes, either.

• Moisture: The humidity not only creates mould and mildew on walls and ceilings, but it can also warp wooden furniture, and musical instruments and wood flooring, while even electronics and leather can be damaged. Just think of your cherished antique table cracking, or your drywall peeling — that kind of expensive damage you want to avoid.
• Lack of Moisture: Too-dry air deserves its due. It may crack drywall, wood furniture and leather. It’s not just cosmetic; over time it can affect the structural integrity of your home.

That’s what a humidistat is for, your home’s own bodyguard, so to speak, to protect from these unseen dangers and guarantee your home has a long life.

Saving Energy: Lower Bills, More Comfort

Here’s a solid bonus: too much or too little humidity can actually cost you money.

• Perceived Temperature: When air is too humid, the feel of it is warmer than the actual temperature. When it’s too dry, it seems colder. This powerfully tends to induce you to crank up the air conditioning or the heat more than you really need and burn more energy, and therefore drive up those utility bills.
• AC Efficiency: Your air conditioning system has to work longer keep a comfortable humidity balance. By maintaining proper humidity levels, your humidistat helps your heating and cooling system work more efficiently, lessening the work load on your system, and possibly decreasing your energy consumption. It’s about working smarter, not harder.

So essentially, a humidistat does not only make you feel great; it keeps your home together and more money in your pocket.

Types of Humidistats: All the Ways to Keep Control

Just as there is more than one way to brew a coffee, there are a couple of flavours of humidistat also out there.

• Analog Humidistats: These are classic, usually with a manual dial or gauge to adjust your preferred humidity. Minimal, functional, less exact.
• Digital Humidistats: A step up, these include digital displays, which work on a similar principle to your thermostat at home, providing more accurate readings and permitting more precise adjustments using buttons or touchscreens. You have real-time monitoring and that’s a game changer.
• Smart Humidistats: This is where the nerdy part comes into play. These bad boys will connect to your Wi-Fi, so you can control them via your phone remotely. They can even connect to other smart home systems, learn from your habits and adjust based on the weather, leading to significant energy savings and convenience.
• Whole-Home Humidistats: Molded directly into your HVAC system, whole-home humidistats act with your air conditioner and heater to regulate the humidity in your home in general, rather than only one room. You generally won’t need to do as much maintenance as with portable units, where water buckets need to be refilled routinely.
• Laboratory-Scale Humidistats: Now we’re talking, these are the big boys, commonly built to the specification for very precise and stable control of humidity in scientific experiments. They accomplish the air mixing using microcontrollers, such as those in the Arduino, advanced sensors, and proportional solenoid valves that together deliver exact amounts of dry and humid air. That may seem like overkill for your home, but the technology behind these products illustrates just how precise humidity control can be.

But for most homes, it’s likely a digital or smart humidistat that’s wired into your existing HVAC is the best play.

How Your Humidistat Works (The Simple Version)

You don’t have to be an engineer to grasp this, but it helps to know the basics. A humidistat basically operates by constantly checking the relative humidity (RH) of the air. RH is essentially the ratio of the amount of water vapour in the air compared to the maximum it can hold at a specific temperature, typically written as a percentage.

Here is the simple chain of events explaining their fears:

1. Feeling with the Air: The humidistat is a moisture sensor. These sensors can be quite nifty, sometimes working by measuring the the difference in electrical resistance or capacitance of the air due to the presence of moisture. As an example: a typical sensor such as the AM2302 (DHT22) uses a polymer capacitive element; the capacitance of the polymer varies by the relative humidity.

2. The Brain (Microcontroller/Control Board): The sensor reports its readings to a “brain” — a microcontroller (such as an Arduino Uno in lab settings) or a specialized control board in your home device. This brain is measuring the current humidity reading (the Process Variable or PV) and comparing it to your set level (the SetPoint or SP).

3. The Decision Maker (PID Control): In higher end humidistats, including high precision ones used in laboratories, this brain utilizes what’s called PID (Proportional-Integral-Derivative) control. Now stay with me, because while there are a few equations involved, PID is basically an intelligent algorithm that’s always working out how much to tweak things to get the humidity just where you want it, and then keep it there, even if something changes. It learns from mistakes of the past and tries to anticipate errors in the future, to ensure the system reacts rapidly and smoothly.

4. Calling the Shots (Actuators): When the humidity isn’t right, a signal is sent by the brain of the humidistat.

• If it’s too dry: It triggers a humidifier to take the air’s moisture up a notch. This action may be opening a solenoid valve to discharge a mist of moisture, or turning on a motor which moves a humidifier drum.
• If it’s too moist: It tells a dehumidifier or even your air conditioner to suck away the extra moisture. This might mean switching on a compressor or circulating fan.

5. The Loop: The entire system is a feedback control system. The humidistat is constantly re-measuring, re-assessing and re-adjusting, resulting in a constant up and down cycle to reach and maintain your desired humidity setting.

How to Set Your Humidistat: It’s a Moving Target

This is not a year-round, set-it-and-forget-it proposition. Just as your wardrobe changes with the seasons, so will your ideal humidity levels.

Comfort Zone: Around 30%-60% RH is common for an indoor environment during dry or wet months. Some even go up to 60% in some climates.

Here, polled from a variety of vets, is a loose sketch guide for winter conditions, according to outdoor temperatures:

• Winter Tweaks: When it’s cold out, the air is typically drier. If you maintain the level of indoor humidity too high, there is a chance for the condensate on windows and walls, which in turn can cause growth. So you’ll want to shoot for the lower end, perhaps 30-40%.
• Summer Changes: Your home will be overtaken by high humidity spikes in the summer months, creating an uncomfortable and muggy air throughout your home. If you’re sensitive to that sticky sensation, you’ll probably want to turn your humidifier down a notch, to about 40-50%, Cates says.
• While You’re Away: If you plan on being away for an extended period of time, setting your humidistat at around 58% with the temperature at around 25°C (78°F) for around 25°C can keep levels consistent.

In the end, it really depends on your own comfort level and actual climate. If you see condensation or still feel uncomfortable, adjust the settings until it feels right.

Where to Place Your Humidistat: Location, Location, Location

Placement matters for accurate readings and for controlling humidity.

• Whole-Home Systems: If you have a whole-home system integrated into your HVAC system, then the humidistat probe is usually mounted in the return air duct, and in most cases upstream (before) of the humidifier unit. This particular spot will provide a good average reading of the humidity in the air that’s being distributed throughout your home.
• Single Rooms: If you are a single room or you have a specific problem area such as a wet basement or attic, then your air compressors humidistat should be placed within that area itself. If you’re in a bathroom, for example, install it high and well outside the confines of the shower.

Crucial Fact: A humidistat will only measure humidity in the local area around itself. “Just a few feet away, the air might be different. That’s why some experts advise purchasing an additional, portable hygrometer. This stand-alone unit can be put elsewhere in the room to verify the readings on your humidistat and ensure a properly controlled whole room. It’s your second set of eyes, making sure you don’t over-humidify or miss a spot.

Humidistat Troubleshooting: When Things Don’t Add Up

The best of tech can have a bad day. If the humidity level at your house is running away without your humidistat, here’s how to find out what’s going on.

How To Tell If Your Humidistat Is On The Blink

• Extreme Swings in Humidity: Your home’s humidity levels are erratic and change significantly.
• Stubborn Mold: Mold is still appearing on your walls, even though you believe your humidistat is functioning.
• Discomfort: You’re sticky and dry (or not) despite what your humidistat tells you.
• System Failure: Your humidifier or dehumidifier is not turning on (or off) when it should be.
• Eerie Sounds / Sky-High Bills Your system is making all sorts of strange noises, or your energy bills suddenly skyrocket when it’s definitely doing nothing but cooling.

Simple Checks Before You Bring in the Cavalry

1. Power Up: Start by making sure the device is plugged in and turned on. Check the pilot light. If it is off, inspect the outlet, circuit breaker, or unit fuse.
2. Float Switch: A float switch is found in many humidifiers (primarily drum models), which won’t run when the water pan is either empty or full. Disconnect the unit and bypass the float switch by jumping the wires. If the unit now powers up when plugged back in, you have your culprit: a bad float switch.
3. Turn Up the Setting: Changing the setting may help, if you are using the device for a humidifier, try turning the humidistat to its highest setting – on the other side, it is fine to turn the humidistat to its lowest setting for a dehumidifier. If it is still unresponsive, you may have a more serious problem.
4. Sensor Cleanliness And, sometimes, it really is just dirt. Clean any sensors and ensure there are no blockages around the unit.
5. Water Supply (for Humidifiers): Make sure your humidifier’s water line is open and water is flowing. Push the float down to test the valve. If it’s a steam humidifier, inspect the injector nozzle to see if it’s blocked.
6. Solenoid Valve: On a humidifier, if your water isn’t moving through it, you may have a broken solenoid valve. When it receives a 24-volt electrical signal, this valve opens to allow water flow. You can test it yourself with a multimeter to confirm that it’s being powered and that it’s opening when you send a signal.

When to Bring in the Pros

If that doesn’t solve your problem, or if you’re working with electrical parts and are not confident, just don’t fuck around. Call an HVAC professional. They have the equipment and know-how to diagnose more general problems like a broken fan motor, a compressor problem or a control board failure. For example a compressor problem may require a replacement refrigeration gas and that is certainly not a job for you.

Humidistat vs. Hygrometer: The Distinction You Should Know

This is one that leads to confusion, but let’s unconfuse it.

• Hygrometer: This is instrument for measurement. Its purpose is to let you know what the humidity level is, plain and simple. It’s like a thermometer for humidity. It gauges but it doesn’t do anything about it.
• Humidistat (or Hygrostat): A control. It includes a hygrometer so that it can detect the humidity, but its primary function is to do something further with that information. It’s what makes your humidifier or dehumidifier come on or shut off in order to keep the humidity level where you want it.

So, your hygrometer says it’s 70% RH or whatever, and the humidistat takes that info and does something about it so the thing clicks on and off until your house/onboard/moldy-bike-room is back in your personal, preferred range. Big difference.

The Future is Smart: The Hydration Edition

The game is changing, and smart humidistats are at the forefront. These aren’t gimmicks, they’re real power tools that make your life easier and make you more productive.

• Remote Control: Connect your humidifier, use 4L, 1 Gallon, 2 Gallon tank, directly with your smartphone with Honeywell’s evohome app. Returning to an air-conditioned home after a sweaty day? Kick on the dehumidifier from your desk, even.
• Automation: They can change automatically based on real-time data, weather forecasts and even learn your habits. That gets you less fiddling and more consistent comfort.
• Compatibility: A lot of smart humidistats will work with other smart home systems — for example, with your smart thermostat or air purifier. This results in a cohesive, customized system in which everything cooperates to maintain your home’s air quality spot-on.
• Insights & Diagnostics: A number of models track data, so, for example, you can see the trend of humidity over time. This makes it easier for you to catch problems before they turn into expensive messes. And self-diagnostic capabilities allow for you to keep it in great shape longer with notification features such as reminders for maintenance.

A smart humidistat is like living with your own private air quality manager. It’s a good investment that can provide more convenience, possible energy savings and a healthier home.

Wrapping It Up: Your Home’s Best Friend

So, what is a humidistat? It’s way beyond just a sensor pinprick in wall; it’s one of the most important devices to actually DO SOMETHING with your air, one of the things in your home doing the most for your own health and comfort and the long life of your house. And whether you’re looking to protect against nasty mould, static shocks or are just keeping an eye on bills, it’s an essential ingredient for all round indoor air quality. Whether you prefer a simple analog model or go all smart home, accurate humidity control is a decision you won’t regret. It’s the ultimate home upgrade for your home’s unseen “drip.”

FAQ

What is a good humidity level for a house?

The perfect relative humidity for the average home falls between 30% and 50%. That said, it depends on your climate and comfort level for sure. In very cold winters, you may need to drop it a little lower to avoid condensation.

Where is the best location to install a humidistat?

A humidistat probe is typically installed in the return air duct for whole house HVAC systems. It’s to be installed on a wall for single rooms or problem areas, such as a bathroom, where you need to monitor humidity, preferably high up and away from direct sources of moisture such as a shower.

Would a humidistat take precedent over a thermostat?

Yes, in a way. Just as a thermostat regulates temperature, a humidistat regulates humidity. If the humidity is too high or too low, your humidistat can tell your HVAC system (which includes your air conditioner as well as your humidifier/dehumidifier) to turn off or on, even if the temperature setting hasn’t been reached. This way humidity is controlled separately.

How frequently should I monitor the setting on my humidistat?

It’s a good idea to do this seasonally, by the way. You’ll want lower humidity in the winter to prevent condensation and higher humidity in the summer for your comfort and to reduce your AC’s labor. Periodic inspection, particularly during severe weather, results in maximum performance.

What is the difference between a humidistat and a dehumidistat?

A humidistat is a generic term for a device that sets or controls the humidity, and can apply to devices that add or remove humidity. A dehumidistat is a type of humidistat whose sole purpose is to operate a dehumidifier to reduce moisture in the air. A humidistat can control either a humidifier and a dehumidifier, or one or the other, depending on the device’s design and how it is incorporated into your system.