Your portable humidifier isn't giving you the moisture coverage you need, and you've decided you're interested in purchasing and installing a ducted, whole-house humidifier. Where do you start? How do you choose the right one?
First, let’s examine the differences between the most common types of ducted whole-house humidifiers: flow-through and drum humidifiers.
How do HVAC Humidifiers Work?
Flow-Through Humidifiers:
- Warm air from your furnace moves through the evaporator pad while water from your water supply moistens the pad.
- That warm air absorbs the moisture to create humidified air.
- Air then flows through the ductwork into your home to evaporate and leave moisture behind.
Drum Humidifiers:
- A rotating evaporator pad spins in the unit's water pan, lifting water into the warm air stream.
- Then, the warm, humidified air is distributed into your home through ductwork.
What's the Main Difference in Operation?
A flow-through humidifier uses an evaporator pad and warm air to create humidified air, while a drum humidifier uses a rotating pad to create moisture.
Ease of Installation
Powerful performance is ideal, but you also want a humidifier that's easy to set up. Each whole-house humidifier type has its benefits and drawbacks regarding installation.
Flow-Through Humidifier Installation
- The installation location on your furnace is on either the warm air supply or the cold air return plenum.
- Requires a nearby floor drain.
- Installation kit usually included.
- DIY or professional installation.
Drum Humidifier Installation
- The installation location on your furnace is on either the warm air supply or the cold air return plenum.
- No floor drain is required.
- Installation kit usually included.
- DIY or professional installation.
Which Has the Most Moisture Output?
If you're looking for a humidifier with the most moisture output possible, a drum humidifier typically delivers more moisture than flow-through models.
How Efficient is an HVAC Humidifier?
Flow-Through Humidifier Efficiency
Generally, flow-through whole-house humidifiers are around 30% to 40% efficient. For example, one gallon of water is delivered into the air for every two gallons of water that flows through the humidifier.
Drum Humidifier Efficiency
On the other hand, drum whole-house humidifiers are 100% efficient. All water supplied to the humidifier is transformed into humidity.
What Do Whole-House Humidifiers Cost?
Now, it comes down to everyone's favorite topic: price. How much does buying, running, and maintaining an HVAC humidifier cost?
Generally, flow-through humidifiers have slightly higher prices and will use more water but have less frequent maintenance and lower maintenance costs.
On the other hand, drum humidifiers have a lower initial price point but typically have higher annual maintenance costs.
The Bottom Line
Flow-through and drum humidifiers each have unique benefits. Selecting the right one for you depends on several factors, including the desired installation location, the importance of efficiency, and annual operating costs.
Still Have Questions?
We know choosing a whole-house humidifier is a challenging decision. To learn more about humidifiers and how to shop for one, visit our Humidifier Knowledge Center. Or, if you’re unsure what's the best fit for you, we can help take the guesswork out of decision-making. Call us at 1-800-934-9194.
Check Out These Other Helpful Resources
- Sylvane's Bestselling Whole House Humidifiers
- Humidifier Buying Guide
- Honeywell Flow-Through and Drum Humidifiers
