Installing A Whole-House Dehumidifier: A Complete Guide

Liz Yang

Installing a whole-house dehumidifier is not as simple as placing a portable dehumidifier in the room. It could be costly, time-consuming, and complicated. 

In this post, I will talk about why you should install it, different installation methods, and then discuss the installation fees.

I am sure you will have a much better understanding of how to install a whole-house dehumidifier properly after reading this post. 

Why should you install a whole-house dehumidifier?

The indoor humidity level is a crucial factor that will affect your house’s overall comfort and air quality. When the humidity is too high, mold and dust mites will start to thrive, and your furniture will swell and warp. 

To prevent these problems, you should use a dehumidifier. While air conditioners can remove excess moisture, they cannot be used all year due to the cooler temperatures in the spring and fall.

A whole-house dehumidifier has a higher upfront cost than a portable model. However, it can keep every house space in good condition, and you will feel comfortable wherever you want to stay. 

You only need a dehumidifier to regulate your house’s humidity level, rather than running a portable model in each room. 

If you want to figure out whether or not you need a whole-house dehumidifier, check here: do you need a dehumidifier for HVAC system or furnace?

How to install a whole-house dehumidifier?

It is advisable to contact an HVAC company or hire a pro to get it installed unless you have the expertise in this field. 

However, even if you decide to pay for an HVAC expert, you’d better have some fundamental knowledge of the installation methods. At least you can know which method fits you better. 

Method 1: Connect a dedicated return to supply 

This is the method most people opt for these days. It is like building a separate dehumidifying system from the air conditioning system so that your house can get rid of the moist air on colder days without running a fan to pull the air.

The crucial steps include:

1. Find a place to put your whole-house dehumidifier, like hanging it on a metal pan. 

2. Install a new return-air grille in the hallway or other appropriate places. 

3. Connect the return-air duct to the inlet of your dehumidifier. 

4. Connect the supply-air duct to the outlet of your dehumidifier. 

5. Attach the other end of the supply-air duct to the supply duct of your HVAC system.

This video from This Old House is great for showing the whole process. 

Pros

1. Independent operation. Since the air doesn’t need to pass through the evaporator coil of your central AC, the dehumidifier can run independently. The whole-house dehumidifier is powerful enough to pull and push the air without using an air handler fan. 

2. Save more energy. Running a dehumidifier can make the room feel cool, meaning that you can set the thermostat higher in summer and save cooling costs. In addition, you don’t need to run an air handler fan by installing it this way, which can save even more energy.

Cons

1. The air feels warm when you stay under the supply-air grille. A dehumidifier blows warm air because the cold and dry air will be reheated before returning to the room. But since the air temperature is slightly above the ambient temperature and we will feel cooler in dry climates, it is not a big idea. 

Method 2: Connect a dedicated return to existing return 

Sometimes, connecting your furnace dehumidifier to the supply plenum is not applicable. In this case, you can connect it to the existing return duct. 

The installing process usually includes these steps:

1. Place your whole-house dehumidifier in a flat and safe place. 

2. Take apart the return-air duct from the air conditioner and connect it to the inlet of the dehumidifier. 

3. Connect the dehumidifier’s vent to the air conditioner’s inlet through a new return-air duct. 

Pros

1. Easy to install. You don’t have to install a separate return-air grill (you can still). Meanwhile, you don’t need to cut the hole and connect the dehumidifier to the supply.

Cons

1. Need to run with a fan. If you install the whole-house dehumidifier in this way, it means that the air coming out from the dehumidifier will pass through the evaporator coil of the AC before getting into the supply duct. To pull the air 

2. Not so efficient. As I mentioned previously, the dehumidifier will release warm air. When this air gets into the AC, the AC needs to work harder to cool down the air, adding to your electricity bill. If you turn on the dehumidifier after turning off the AC, the dry air will absorb the moisture in the coil and then take it to your room. 

Cost of installing a whole-house dehumidifier 

Except for the product price, there is some cost you need to pay while installing a whole-house dehumidifier. 

Labor cost

On average, the labor rate in the US ranges from $50 to $150, and it will take around 2 to 5 hours to install it. Therefore, the labor cost would be around $100 to $750.

Ductwork

You need to add a dedicated return duct and install a separate return-air grill (optional). The cost of ductwork will be around $250 to $500. External pump

The condensate of your whole-home dehumidifier needs to drain through the hose. You need to use a pump if the water can’t flow from up to down. This pump can cost around $70 to $125. 

In a word, the cost of installing a whole-house dehumidifier can cost around $400 to $1400. 

Conclusion 

You can reap a lot of benefits by installing a whole-house dehumidifier. However, installing it is not a walk in the park. 

There are two ways to install it but adding a dedicated return duct to the supply is a better choice since it has higher efficiency and saves more money. However, it takes more work to install compared to adding it to an existing return duct. 

Beyond that, installing a whole-house dehumidifier can be pricey. On top of the labor cost, you need to pay for the ductwork, external pump, and other accessories. 

Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested a lot of products in person, like humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.

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