In winter the air in your heated house gets really dry and can lead to allergies, skin irritations and even nosebleeds. To ensure that the air in your home remains at the ideal humidity you need to install the best furnace humidifier that matches the size of your home, as well as your budget.
Furnace humidifiers, also known as whole house humidifiers, come in a few different configurations. Each of these different types have furnace humidifier pros and cons that you'll need to consider.
We’ve put together some furnace humidifier reviews of the 10 best whole house humidifiers on the market as well as a buying guide to help you choose the best furnace humidifier for your needs.
Best Furnace Humidifier Comparison Table
Best Furnace Humidifier Reviews
We've put together whole house humidifier reviews of our top 10 units.
If we were looking to buy the best furnace humidifier for the money then it would be this one. A lot of furnace humidifiers struggle to adequately humidify large homes but not this unit.
It does a great job with bigger homes and will humidify a tightly sealed home of up to 4,200 square feet making it the best whole house humidifier on the market. If you compare this unit with similarly priced humidifiers you’ll find that it produces as much as 50% more moisture.
It has an evaporation capacity of 0.75 gallons per hour which is among the highest we’ve seen for these kinds of humidifiers.
The automatic controller provides temperature and humidity readings as well as important service information. While it has the automatic function you can also run it in manual mode. Installation was pretty simple and the instructions were very clear.
The controller needs to be mounted on the humidifier so make sure you choose a spot that you can easily access to change settings. It runs really quietly as well. Even when you’re in the basement all you hear is the solenoid clicking on and the sound of water entering the humidifier. If you're looking for the best furnace humidifier then this is the one to buy.
Honeywell have a well earned reputation for making great temperature and humidity control devices. If you read home humidifier reviews then you'll see many of their products listed.
This powered flow through humidifier is simple to install and is one of your best options if you have a variable speed or multi-stage furnace system in your home.
It is designed to humidify homes of up to 4,200 square feet. The instructions aren’t the greatest but installation was fairly simple and took around 2 -3 hours. Amazon say that a separate installation kit is required but ignore this.
It comes with supply & drain tubing, a tapper valve and a mechanical humidistat. You might need some more ¼ inch tubing. We’d recommend getting a sail switch (Honeywell S688 Sail Switch) so the humidifier knows when the furnace is on.
Using the sail switch will save you having to mess with electrical wiring from the furnace to the humidifier. It works really quickly and you’ll feel a noticeable difference in your home within a few hours. It runs pretty quietly and you certainly won’t hear it over your furnace.
The concern some people have with bypass humidifiers is how much water they use. This is one of our favorite bypass units because it’s drainless and is designed to use 100% of the water going into it.
Instead of having the water continuously flowing into the tray it senses when a little cup below the pad is full and then shuts the water off.
This way you get the benefit of no drainage while also avoiding the issues that go along with stagnant standing water.
The only time you’ll see any water draining out of this unit is if there’s a problem with the shutoff, or a blockage somewhere.
It comes with an automatic digital controller that is fairly simple to use and gives feedback on temperature, humidity and service info. This unit has an evaporating capacity of 0.7 gallons per hour and is suitable for homes of up to 4,000 square feet. It's not surprising that we keep seeing this unit in furnace mount humidifier reviews.
If your house doesn’t have a forced air system then a steam humidifier is your best bet. This whole house steam humidifier is also a great solution if you want a humidifier that runs independently of your furnace.
It regulates the humidity according to the control it receives from the automatic humidistat and simply turns the furnace blower fan on when it needs to send humidity into your home.
This makes for far more efficient running of the humidifier. You can also wire it to work only when your furnace is on if you want.
Maintenance of these whole house humidifiers is really simple. No need for filter, or pad replacements. Simply give the water reservoir a clean once a year and you’re all set. If you have really hard water then you may need to do some descaling eventually. In this case it might be a good idea to install a water softener.
If you’ve tried without success to get your home’s humidity up to an optimum level then it may be time for a good steam humidifier. This is one of the best steam humidifier options if your house is 2,500 square feet or smaller and you'll see it feature regularly in whole house steam humidifier reviews .
Some bypass flow through humidifiers struggle in larger homes but this high capacity unit is rated for homes of up to 4,000 square feet.
Installation is really simple and mounts on either supply or return ducts. Amazon says that it needs a separate installation kit but that’s not the case.
It comes supplied with tubing, clamps, humidistat and filter, which is pretty much all you need.
The installation kit comes with a sail switch, solenoid with transformer and some extra ducting bits. You’re better off buying your own sail switch or just pick up the 24V straight from your furnace.
The instructions that come supplied with the unit aren’t the greatest but there are better instructions available on the internet. The instruction sheet serves as the template for the cutout of the duct so that’ll save you some measuring.
This is not the cheapest furnace humidifier but it is one of the best powered fan humidifiers available.
It’s part of their Elite series and comes supplied with a digital humidistat and the controller allows for automatic or manual operation.
It also has an outdoor sensor to control based on outdoor relative humidity and indoor temperature. If you have a medium sized home then this is a good option as it is rated for homes of up to 3,000 square feet.
The humidifier comes with an integrated humidity control bypass damper so that you can easily isolate the humidifier during the summer months when you’re using your AC. It comes with a 10 year warranty but this is only valid if you have it installed by a professional contractor.
The 600M is one of the best bypass humidifiers on the market today. This 24V unit delivers as much as 50% more humidity than other similarly priced units.
It evaporates 0.7 gallons per hour and is capable of humidifying a home of up to 4,000 square feet.
There is an integrated bypass damper that is operated by a small handle. The label on the bypass makes it easy to adjust the damper for summer or winter.
The “M” in the model number indicates that this comes with a manual humidistat controller. These are really simple to set so there’s no fiddling with digital controllers. You can, of course, get rid of the manual humidistat controller and connect it up to a smarter thermostat that has humidity control if you prefer.
If you experience big winter temperature variations where you live then the 600A, with it’s automatic controller and outdoor sensor, may be worth the extra money. Otherwise, just go with the manual controller. It’s a simpler installation and works beautifully.
If you’re looking for a budget option for a small to medium sized house this drum humidifier is good option if you’re looking for basic humidification.
It comes supplied with an automatic relative humidity control as well as an installation kit.
The great benefit of these drum furnace humidifiers is that they don’t require a drain. 100% of the water that goes into the humidifier gets converted into humidity so no water is wasted.
It has an overflow line but the only time you’ll see anything come out of it is if there’s a problem with the humidifier. The auto shut off valve regulates water flowing into the humidifier but if you have hard water then it can get clogged with scale.
You’ll need to replace the filter at least once a year and give the tray a clean twice a year to get rid of mineral buildup.
This 24V bypass humidifier is a great option for medium sized homes of up to 3,000 square feet.
It’s water use efficiency is pretty good for a bypass humidifier and it delivers 0.5 gallons per hour of humidity.
It comes supplied with a digital controller, an outdoor sensor as well as the 110V to 24V transformer. You can ditch the transformer if you prefer to pick up the 24V from your furnace panel.
This unit also has an integrated bypass damper so you can close it off for the summer months.
It only uses water when the controller switches the humidifier on and the outdoor sensor results in far better control of your home’s humidity.
This was not the easiest humidifier to install, though, so bank on around 5 or 6 hours of work.
Drum humidifiers are not the best furnace humidifier option but if you don’t have access to a drain, or you’re looking to save water, then this is a good budget option.
The housing is made from durable thermoplastic so you won’t get the rust, corrosion and warping issues that some of the older units suffered from. It will provide around 0.7 gallons per hour and is suitable for use in a house of up to 4,000 square feet if it’s tightly sealed.
It comes supplied with an installation kit. If you have hard water then it would be a good idea to get the Skuttle Automatic Flushing Timer as well. This flushes the humidifier periodically with fresh, clean water to prevent mold buildup and reduce cleaning and servicing requirements.
Furnace Humidifier Buying Guide
When you're looking to buy a furnace dehumidifier you first need to select a type and then make sure the capacity is sufficient for the size of your home. Here are some pointers to help you make a good choice when buying the best whole house humidifier.
Types Of Furnace Humidifiers
Whole house humidifiers, or furnace humidifiers, come in 4 main types. We've listed the furnace humidifier pros and cons of each type below.
Bypass Flow-Through Humidifier
With a bypass flow through humidifier some of the warm air from the supply side of the furnace is directed into the bypass duct of the humidifier. The humidifier has a tray that allows water to flow onto a pad that soaks up the water. The warm air that passes across the pad causes some of the water to evaporate and this evaporated water joins the air in your duct and humidifies it.
The ducting then takes the warm, moist air into your house. It’s called a flow-through humidifier because the water that isn’t absorbed by the pad flows through it rather than being collected in a pan. This flushes the unit continually which helps keep the unit clean. These units normally need to drain excess water into a drain but you do also get drainless bypass humidifiers. In duct humidifier reviews will normally state that this type is the best whole home humidifier option to go for.
Drum Furnace Humidifier
These are very similar to the bypass flow through humidifier but they have a rotating evaporator pad rather than a stationary one. The pad rotates through a pan containing water and the water is then lifted into the warm air as it continues to rotate. The evaporated water is then carried into the ducting of your system.
These units are 100% efficient as they don’t lose any water and they deliver more humidity than the regular bypass units will. They are prone to buildup of mineral deposits, mold and bacteria because of the water that lies stagnant in the pan. To avoid this you can get an automatic flushing timer that flushes clean water through your humidifier periodically and prevents mold and mineral buildup.
Fan-powered furnace humidifier
A fan-powered humidifier, also simply known as a power humidifier, has a built in fan that blows air across the water soaked pad. Because it generates its own air flow it doesn’t need warm air to be ducted into it to cause the water to evaporate.
You would typically get about a gallon more humidity from these units than you would from a bypass humidifier. Because you don’t have to install a bypass duct these humidifiers are a good choice if you’re trying to fit a furnace humidifier into a tight space.
Steam Furnace Humidifier
A steam humidifier boils water to create humidity and then this steam is fed into the supply duct of your furnace system. These are a great solution if you’re looking for fast and efficient humidifying of your home. Because they don’t need hot air pushed into them these can be used in a home that doesn’t have a forced air system. They use a lot less water than the bypass units but they do use a lot of electricity.
Whole House Humidifier Ratings:
Once you've decided on which type of furnace humidifier to buy you need to decide on a specific model. Home furnace humidifier reviews will often quote a number of details but these are the two main ones you should look out for:
Furnace Humidifier Coverage - The capacity of the furnace humidifier is given in square feet and indicates the maximum size home that the humidifier would be able to humidify. Bear in mind that this figure is given based on your home being tightly sealed. Take this figure with a pinch of salt and rather choose a humidifier with a slightly higher capacity than your home’s actual square footage. (Similar thought goes into choosing the right size dehumidifier.)
Furnace Humidifier Output capacity - This is quoted in gallons per hour or gallons per day and indicates how much moisture your humidifier will deliver into the air. If your air gets very dry then go for a higher gallons per day rating to make sure you get the humidity you're after.
Furnace Humidifier Installation
Your furnace humidifier will no doubt come with comprehensive installation instructions specific to the model that you buy. That being said, here are some general installation issues to remember.
- When cutting into the ducting to install your furnace humidifier make sure that you don’t drill into your air conditioning coil. You can usually see where the coils are by looking for small copper tubes that will be coming out of the ducting. You want to mount the humidifier at least 1 inch away from the air conditioning coil.
- Remember that at some point you will need to perform some routine maintenance so make sure that you leave enough room around the unit so that you can easily access it later.
- Do not install the humidifier on the furnace itself.
- Some furnace humidifiers require external drainage so make sure the unit is within close access to a floor drain.
- Make sure that it’s close enough to the water supply so that your feed hose will reach.
- Depending on which furnace humidifier you buy, it may require installation by a licensed HVAC professional. Make sure that your warranty will still be honored if you do the installation yourself.
- If your humidifier uses a humidistat then this can be installed on your cold air duct or, preferably, on a wall in your living space.
- Flow through bypass furnace humidifiers can be mounted on either the supply side or return side of the furnace. The air being ducted to the intake, or bypass duct, of the humidifier needs to come from the warm air supply side though as this is used to promote good evaporation of the water in the pad.
- Fan powered furnace humidifiers can only be installed on the supply plenum of a forced-air furnace system.
- If you have an electronic air cleaner in your system then make sure that your humidifier is installed downstream from this.
- With a steam furnace humidifier the output of the humidifier needs to be directed into the supply duct.
Whole House Humidifier Installation - Return Side or Supply Side?
The short answer is: It doesn’t really matter. If you’re installing a flow through bypass humidifier then, technically, you can install it on either the cold air return side or on the warm air supply side.
Your best bet is to follow the recommendation in the instruction manual. If you’re struggling to decide then look for which option will give you the easiest access for future maintenance.
There are some benefits to installing on the cold air return side, though. On the off chance that your humidifier develops a water leak then you won’t be leaking water into your furnace.
Just remember that if you’re installing a fan powered flow through humidifier then it must be installed on the supply side. Also, your humidistat needs to be installed upstream from the furnace humidifier.
Do I Need A Bypass Damper?
While some furnace humidifiers come with a built-in damper this is not always the case. You only really need a bypass damper if you have a bypass humidifier and your system also incorporates air conditioning. During the warmer months you need to make sure that the bypass duct to your humidifier is blocked off.
Your furnace humidifier may have a built-in damper that you can turn or you may need to install one in your ducting. You could also slide a sheet of metal between the bypass duct and the supply duct.
Not using a damper can reduce the effectiveness of your air conditioner or even cause it to ice up and get damaged.
What Is The Optimum Humidity For My Home?
During winter your home is heated and the moisture that is normally in the air is dried out. This leads to very dry air that can feel quite uncomfortable and can even lead to some health problems like allergies.
When the air is too dry it can also lead to warped wood flooring, cracked leather upholstery, wood finishings and buildup of static electricity.
The optimum humidity level to maintain in your home is around 35% to 55%. Any higher than this and you could end up with mold developing.
You can get a cheap hygrometer and keep it somewhere in your living space to make sure that your air is within these limits.
A great benefit of having more humid air in your home is the comfort factor and energy savings you can achieve. Dry air doesn’t store heat very well.
Moist air, on the other hand, retains heat a lot better so your house will feel warmer when the humidity is a higher.
This means that you can set your heating down a few degrees and still feel comfortable while saving on your heating bill. If your home gets too humid in summer then you’re going to need to buy a good dehumidifier.
In general whole house humidifiers are designed to work in the 35% - 40% humidity range. The temperature of the air outside and the relative humidity of the air inside your home will have an effect on how effective your humidifier is at regulating the humidity.
Relative humidity is a measure of how much moisture air can hold at a specific temperature. Depending on the temperature outside of your home you could end up with condensation on the inside of your windows that could eventually lead to mold.
To cater for this, some of the better humidifiers use an outdoor temperature sensor to better regulate the indoor humidity. If you find that you wake up in the morning with some condensation on your windows and you don't have one of these smart humidifiers then just reduce the humidity setting on your humidifier a little.
As the temperature outside fluctuates you may need to make additional adjustments.
If you heat your home during winter then buying the best furnace humidifier is essential. Having the best whole house humidifier will make your home feel more comfortable and you’ll avoid those winter nose bleeds and dry skin.
Read our furnace humidifier reviews above and then make sure that you choose one that is rated for the size of your home. Also, be aware of the pros and cons of the different types of furnace humidifiers.
Once you’ve installed your furnace humidifier and got the humidistat setting just right then you shouldn’t have to touch it again until it’s time for your end of winter maintenance.
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