Adding a whole house dehumidifier can dramatically improve your home’s air quality, comfort, and energy efficiency. This guide walks you through every step—from choosing the right unit to installation and maintenance—so you can enjoy drier, healthier air throughout your home.
Quick Answers to Common Questions
Tip/Question?
Can I install a whole house dehumidifier myself?
Tip/Question?
While DIY installation is possible, we recommend hiring a licensed HVAC technician to ensure safety, proper integration, and warranty compliance.
Tip/Question?
How often should I clean the filter?
Tip/Question?
Clean or replace the air filter every 1–3 months, or more often if you have pets or high dust levels.
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What’s the ideal indoor humidity level?
Tip/Question?
Keep indoor humidity between 30% and 50% for optimal comfort and mold prevention.
Tip/Question?
Do I need a condensate pump?
Tip/Question?
Only if you can’t gravity-drain to a floor drain. A pump is needed when the drain is above the unit or far away.
Tip/Question?
Will a dehumidifier lower my energy bills?
Tip/Question?
Yes—by making air feel cooler, you can raise your thermostat in summer, reducing AC usage and saving energy.
How to Add Whole House Dehumidifier
High humidity in your home can lead to a host of problems—mold growth, musty odors, warped wood, and even health issues like allergies and respiratory discomfort. While portable dehumidifiers work for single rooms, they’re not practical for larger homes. That’s where a whole house dehumidifier comes in. These systems are designed to remove excess moisture from the air throughout your entire home, working seamlessly with your HVAC system.
In this comprehensive guide, you’ll learn how to add a whole house dehumidifier the right way. We’ll cover everything from assessing your home’s needs and choosing the best model to installation, maintenance, and troubleshooting. Whether you’re a DIY enthusiast or planning to hire a pro, this guide will give you the knowledge and confidence to improve your indoor air quality and comfort.
Why You Need a Whole House Dehumidifier
Before diving into installation, it’s important to understand why a whole house dehumidifier is worth the investment. Unlike portable units that only treat one room at a time, whole house models connect directly to your home’s ductwork. This allows them to treat air as it circulates through your heating and cooling system, ensuring consistent humidity control in every room.
Visual guide about How to Add Whole House Dehumidifier
Image source: static.grainger.com
Here are the top benefits:
- Improved Air Quality: Lower humidity reduces mold, mildew, dust mites, and other allergens.
- Enhanced Comfort: Air feels cooler and less sticky when humidity is controlled, even at higher temperatures.
- Energy Savings: Dry air feels more comfortable, so you can set your thermostat higher in summer without sacrificing comfort.
- Protects Your Home: Prevents damage to wood floors, furniture, and drywall caused by excess moisture.
- Reduces Odors: Musty smells from damp basements or crawl spaces disappear.
If you live in a humid climate, have a basement, or notice condensation on windows, a whole house dehumidifier is likely a smart upgrade.
Step 1: Assess Your Home’s Humidity Needs
The first step in adding a whole house dehumidifier is determining whether you actually need one—and if so, what size and type will work best. Start by measuring the current humidity levels in your home.
Check Indoor Humidity Levels
Use a hygrometer (a small, inexpensive device available at hardware stores or online) to measure the relative humidity (RH) in different areas of your home. Ideal indoor humidity should be between 30% and 50%. Levels above 60% create a breeding ground for mold and dust mites.
Check multiple locations, especially in basements, bathrooms, and laundry rooms—areas prone to high moisture. Take readings at different times of day, as humidity can fluctuate.
Evaluate Your Home’s Size and Layout
Whole house dehumidifiers are rated by how many pints of moisture they can remove per day. To choose the right size, consider:
- Square footage: Larger homes need higher-capacity units.
- Climate: Homes in humid regions (like the Southeast U.S.) may need more powerful systems.
- Number of occupants: More people = more moisture from breathing, cooking, and showering.
- Basement or crawl space: These areas often require additional dehumidification.
As a general rule:
- Up to 2,500 sq. ft.: 30–50 pint unit
- 2,500–4,000 sq. ft.: 50–70 pint unit
- Over 4,000 sq. ft.: 70+ pint unit
Some manufacturers provide online sizing calculators—use them to get a more accurate recommendation.
Identify Problem Areas
Walk through your home and look for signs of excess moisture:
- Condensation on windows or walls
- Peeling paint or wallpaper
- Musty odors
- Warped wood or flooring
- Visible mold or mildew
If you spot these issues, a whole house dehumidifier can help—but you may also need to address underlying causes like poor ventilation, leaks, or inadequate insulation.
Step 2: Choose the Right Whole House Dehumidifier
Not all whole house dehumidifiers are created equal. There are several types and features to consider before making a purchase.
Types of Whole House Dehumidifiers
There are two main types:
1. Bypass Dehumidifiers: These are integrated into your HVAC system and use your furnace or air handler to circulate air. They’re energy-efficient and ideal for homes with central air.
2. Standalone (Ducted) Dehumidifiers: These are self-contained units that connect directly to your ductwork. They have their own fan and don’t rely on your HVAC system to move air. Great for homes without central air or in humid climates.
Most homeowners opt for a bypass model because it’s more efficient and easier to install with existing systems.
Key Features to Look For
When shopping, prioritize these features:
- Capacity: Match pints per day to your home’s needs.
- ENERGY STAR Certification: Ensures energy efficiency and lower operating costs.
- Humidistat: Allows you to set and maintain a target humidity level automatically.
- Automatic Defrost: Prevents ice buildup in cold environments (important for basements).
- Drainage Options: Look for models with built-in condensate pumps or gravity drain compatibility.
- Warranty: At least 2–5 years on parts and labor.
Popular brands include AprilAire, Santa Fe, Honeywell, and Ultra-Aire. Read customer reviews and consult with an HVAC professional for recommendations.
New Construction vs. Existing Homes
If you’re building a new home, it’s easier to plan ductwork and electrical connections for a dehumidifier from the start. For existing homes, installation may require minor modifications to your HVAC system.
Don’t forget to check local building codes and permits—some areas require professional installation for HVAC-related equipment.
Step 3: Plan the Installation
Proper planning ensures a smooth installation and optimal performance. Here’s what to consider before you begin.
Location Matters
The dehumidifier should be installed in a central location within your HVAC system. Common spots include:
- Near the air handler or furnace: This allows the unit to treat air before it’s distributed.
- In the basement: Ideal for homes with basements, especially if that’s where humidity is highest.
- Attic or utility room: Less common but possible if ductwork allows.
Avoid placing the unit in tight, enclosed spaces without ventilation. It needs airflow to operate efficiently.
Electrical Requirements
Most whole house dehumidifiers require a dedicated 120V or 240V circuit. Check the manufacturer’s specifications. If your electrical panel doesn’t have space, you may need to upgrade or install a subpanel.
Always turn off power at the breaker before working on electrical connections.
Drainage Setup
The dehumidifier removes moisture from the air, which turns into water (condensate) that must be drained. You have three options:
- Gravity Drain: Run a hose from the unit to a floor drain, sink, or sump pump. Requires a downward slope.
- Condensate Pump: Use a small pump to push water to a higher elevation (e.g., a sink or outside).
- Self-Evaporating: Some units evaporate moisture back into the air, but this reduces efficiency and isn’t ideal for high-humidity areas.
Gravity drainage is simplest if you have a nearby drain. Otherwise, a condensate pump is a reliable solution.
Ductwork Modifications
Your HVAC technician will need to cut into the ductwork to install the dehumidifier. This typically involves:
- Cutting a section of return duct
- Installing a bypass duct (for bypass models)
- Connecting the dehumidifier with flexible ducting or metal transitions
- Sealing all joints with mastic or foil tape to prevent air leaks
Proper sealing is critical—leaky ducts reduce efficiency and can cause condensation issues.
Step 4: Install the Whole House Dehumidifier
Now it’s time to install the unit. While some homeowners tackle this as a DIY project, we strongly recommend hiring a licensed HVAC technician. They have the tools, experience, and knowledge to ensure safe, code-compliant installation.
Step-by-Step Installation Process
1. Turn Off Power and HVAC System
Before starting, shut off power to your furnace and air handler at the breaker. Also, turn off the thermostat.
2. Mount the Dehumidifier
Secure the unit to a wall or floor stand using the manufacturer’s mounting hardware. Ensure it’s level and stable. Leave enough space around the unit for airflow and maintenance access.
3. Connect to Ductwork
For a bypass model:
- Cut a section of the return duct near the air handler.
- Install a bypass duct that routes air from the return into the dehumidifier and back into the supply duct.
- Use a damper to control airflow through the dehumidifier.
For a standalone model:
- Connect the dehumidifier’s inlet and outlet to the main duct system.
- Use flexible ducting or metal transitions for a secure fit.
4. Install Drain Line
Attach a 3/8” or 1/2” vinyl or PVC hose to the condensate outlet. Route it to your drain or pump. Use clamps to secure the hose and ensure a downward slope for gravity drainage.
If using a pump, install it according to the manufacturer’s instructions and test it with water.
5. Wire the Unit
Connect the dehumidifier to the dedicated circuit. Follow the wiring diagram in the manual. Most units plug into a wall outlet, but some require hardwiring.
If your model includes a humidistat, mount it in a central location (not near windows or vents) and connect it to the dehumidifier.
6. Seal and Insulate
Seal all duct connections with mastic or foil tape. Insulate any exposed ductwork in unconditioned spaces (like attics or crawl spaces) to prevent condensation.
7. Restore Power and Test
Turn the breaker back on and set the humidistat to your desired level (e.g., 45%). Run your HVAC system and check that the dehumidifier turns on when needed.
Listen for unusual noises, check for leaks, and verify that water is draining properly.
Step 5: Maintain Your Dehumidifier
Regular maintenance keeps your dehumidifier running efficiently and extends its lifespan. Here’s what to do:
Monthly Checks
- Clean or replace the air filter (usually every 1–3 months).
- Check the drain line for clogs or leaks.
- Inspect the unit for dust or debris buildup.
Every 3–6 Months
- Clean the evaporator and condenser coils with a soft brush or coil cleaner.
- Check the condensate pump (if used) and clean the reservoir.
- Verify that the humidistat is accurate with a separate hygrometer.
Annually
- Have an HVAC technician inspect the system, check refrigerant levels (if applicable), and test performance.
- Replace worn parts like fan motors or capacitors if needed.
Keep a maintenance log to track when tasks were completed.
Troubleshooting Common Issues
Even the best systems can run into problems. Here’s how to fix common issues:
Dehumidifier Won’t Turn On
- Check power supply and breaker.
- Ensure the humidistat is set correctly.
- Verify that the HVAC system is running (for bypass models).
Not Removing Enough Moisture
- Clean or replace the air filter.
- Check for dirty coils or restricted airflow.
- Ensure the unit is properly sized for your home.
Water Leaking or Not Draining
- Clear clogs in the drain line.
- Check the condensate pump (if used).
- Ensure the drain hose has proper slope.
Unit Freezing Up
- Enable auto-defrost mode (if available).
- Move the unit to a warmer location.
- Reduce runtime or lower the humidity setting.
If problems persist, contact the manufacturer or a professional technician.
Conclusion
Adding a whole house dehumidifier is one of the best investments you can make for your home’s comfort, health, and longevity. By controlling indoor humidity, you prevent mold, reduce allergens, and protect your belongings from moisture damage. Plus, you’ll enjoy a more comfortable living environment year-round.
While the installation process may seem complex, careful planning and the right professional help make it manageable. Remember to choose the right size, integrate it properly with your HVAC system, and maintain it regularly. With these steps, your whole house dehumidifier will deliver reliable performance for years to come.
Don’t let high humidity take over your home. Take control today—your air quality and peace of mind are worth it.