How To Install a Whole House Dehumidifier (DIY Explained)

I use portable dehumidifiers in my house because humidity only really affects my basement and garage.

However, I’ve worked with homeowners who had damp and humid conditions across their entire home, and for them, portable dehumidifiers just weren’t enough. Instead, they needed to have a whole-house dehumidifier installed.

Installing a whole-house dehumidifier can be a big job. and often needs to be done by a professional.

In this guide, I’ll explain the best methods for installing a whole-house dehumidifier, the benefits of each approach, and whether you need to hire a professional or not.

Two Methods of Installing Whole House Dehumidifiers

Dehumidifiers aren’t effective unless they can reach the humid air, and I know from experience that dehumidifier positioning is crucial.

To manage the humidity across an entire house, you need to connect your dehumidifier to your home. This is done through a series of ducts that draw dry air in from various rooms and push dry air back out.

I have seen a lot of different HVAC systems over the past decade, but generally, a whole-house dehumidifier is part of an air conditioning system. The dehumidifier works alongside the air conditioning unit to let you control the temperature and manage humid air, giving you the best possible control of your indoor air quality.

If you don’t have an existing air conditioning system, then you won’t have ductwork and you’ll have to have it all installed.

That’s a major piece of work and while it is possible to do it yourself, I would recommend consulting a professional to fit the ducts. I won’t cover that here, instead, I’ll focus on the best ways for installing a whole home dehumidifier alongside your air conditioning HVAC system.

The image below shows how your dehumidifier can work alongside your HVAC system. There are two methods for doing this and we’ll explore each below.

UltraAire Dehumidifier Installation

Dedicated Return to Supply Installation Method

The dedicated return-to-supply method is relatively new but it’s considered the best way to install a whole-house dehumidifier. This is now the method I always use to install a whole-house model.

Previously, a dehumidifier would only be installed into your existing ductwork using a return to existing return method. This created an extra loop in the system, so the air conditioning process would occur before the dehumidification.

With the dedicated return-to-supply method the air is drawn into the dehumidifier through a separate route. This offers a few key benefits:

  • Independent operation – usually, if you turn off your air conditioning then it can mean your dehumidified air picks up some moisture from the coils. With dedicated return to supply this doesn’t happen because the air takes a different route.
  • Lower humidity – this method lets your dehumidifier work more effectively allowing it to lower humidity levels more efficiently.
  • Less static pressure – static pressure slows air flow down and makes it harder to remove excess humidity. This installation method doesn’t add any additional static pressure, making your air conditioning and dehumidification systems more effective.
  • Better energy efficiency – no air handler fan is needed so there are lower energy costs. Plus, your dehumidifier doesn’t have to work as hard or for as long, translating into energy savings.

The only drawback of this method is the dry, warm air it releases inside your home. However, this will eventually make its way into the air conditioner to be cooled.

Here’s how to do it:

  1. Install a return duct in your house to connect it to your dehumidifier.
  2. Connect a duct from the dehumidifier discharge to the existing AC supply plenum.
  3. Discharge all the dry air into the supply plenum.
  4. Measure the static pressure. It can sometimes rise with both devices running, but the advantage of this installation is that you can set the dehumidifier and AC to run separately as needed.

Dedicated Return to Existing Return Method

This is the typical method used to install a dehumidifier into your existing HVAC system. This method utilizes the return pipes connected with the existing HVAC system so that air passes through a dehumidifier before entering the dehumidifier.

I have installed a lot of whole-house dehumidifiers using this method in the past but while it can work, this method has some disadvantages:

  • No independent operation – your dehumidifier and AC work through the same ducts and therefore have to be used together.
  • Increased energy costs – an air handler fan has to be used to push the air from the dehumidifier into the air conditioner which will push your energy bills up.
  • Less efficient – dry air traveling through your air conditioner is likely to pick up some more moisture. This means this system is less efficient and will mean your dehumidifier has to work harder to achieve the desired results.

The advantage of this method is that the air is cooled once it’s dried, so only cold air blows into your home. However, this setup is generally less efficient and should only be used if there’s no option for using the return-to-supply method.

Here’s how to do it:

  1. Install your dehumidifier so that your existing AC return ducts connect to your dehumidifier. The ducts should then connect your air conditioner.
  2. Seal return ducts with metal tape or mastic at joints and avoid using only building cavities as return pathways.
  3. Use pressure meters to check the pressure differences. This needs to be balanced for air to flow.

DIY vs Hiring an HVAC Contractor

When it comes to dehumidifiers, I always recommend doing DIY work where possible.

However, taking on repair work is one thing, but actually installing a whole home dehumidifier can be a daunting task. It can be done yourself, or by hiring a contractor and there are advantages and disadvantages to each:

Advantages of hiring an HVAC contractor

  • It’s easier – an HVAC contractor is a master at their job and will come with all the skills, knowledge, and tools to get the job done well with no effort on your part. I wouldn’t underestimate just how much stress you can avoid by hiring a professional.
  • It’s done correctly – a licensed HVAC contractor will have experience installing a whole house unit correctly so you can control humidity properly. They’ll also know how to prevent high static pressure from impacting dehumidifier systems.

Advantages of doing it yourself:

  • It’s cheaper – hiring an HVAC professional to install a whole-house dehumidifier isn’t cheap and could cost you upwards of $1000 just in labor.
  • It can be faster – if you’re doing the work yourself you control the schedule. This stops you from having to wait around for your dehumidifier while the relative humidity levels rise.

Learning how to install a whole-house dehumidifier isn’t simple, but if you have experience with DIY and dehumidifiers then it can be done. However, if you aren’t 100% confident then it’s worth paying a professional so you know it’s done correctly without damaging your air conditioning unit.

Why Install a Whole House Dehumidifier?

A whole-house dehumidifier can be a much better option than an HVAC system and improve a standard air conditioning unit.

Here are some benefits of whole-house dehumidifier installation:

1. Makes Your Home More Comfortable

Humans require approximately 30 to 50% relative humidity and I try to keep my living areas at around 35% relative humidity. Humidity levels above 50% can make you feel hot and sticky and even make it harder to carry out natural cooling processes.

A whole-house dehumidifier will lower the relative humidity to optimal levels and keep you much more comfortable.

2. Reduce Cooling Cost

Air conditioners use a lot more power than a dehumidifier. By using a dehumidifier you’ll make your home feel cooler and you’ll be able to run your AC less frequently. This can save you a lot of money on your bills.

3. Protects Your Home

Moisture and humidity can damage your paint, walls, floors, and warp furniture. In my home high humidity has caused a lot of damage in my basement and ruined some of the belongings I was storing down there. Installing a whole house will regulate humidity levels across your home and protect your belongings.

4. Remove/Reduce Molds Inside Your Home

It is common for mold to develop in areas exposed to excess moisture. A whole-house dehumidifier will remove damp and humid conditions and reduce the chance of mold or mildew forming. This will make the indoor air safer for you and your family.

How Much Does It Cost to Install a Whole House Dehumidifier?

Installing a whole-house dehumidifier will cost $1500-$3500. This is broken down into:

  • Dehumidifier costs – the make, model, and size of your dehumidifier will impact the cost. You should expect to pay $500-$2000 for a whole-home dehumidifier and there may be extra costs if additional components (like internal pumps) are needed.
  • Labor costs – if you choose to hire a professional it will cost $500-$1000 in labor costs. If you choose to do it yourself it’s a lot cheaper.

The exact cost can vary massively depending on the location of your dehumidifier, the layout of your existing HVAC system, and what additional work needs to be done. There may also be additional licensing costs depending on the regulations where you live.


What is the best setting for a whole-house humidifier?

For an ideal indoor humidity level, you should set your whole-house dehumidifier to between 35 to 55% relative humidity. Viruses and bacteria don’t live for too long at this range, and the static shock is also minimized.

Do whole-house dehumidifiers use a lot of electricity?

Whole house dehumidifiers’ energy usage depends on the type you use and how much you use it. The electricity consumption can be from a minimum of 300W to over 700W.

Where should a whole-house dehumidifier be installed?

It is best to place a whole-house dehumidifier on the part of the floor with the lowest temperature, whether it is upstairs or downstairs. The area should also have maximum exposure to moisture.

Do whole-house dehumidifiers remove mold completely?

Dehumidifiers do not entirely remove the mold because it is present and dormant even in those areas without excess moisture. However, the moisture helps it grow, so dehumidifiers prevent that by reducing humidity.


I’ve installed a lot of whole-house dehumidifiers, and they can really help anyone dealing with a lot of humidity.

It is possible to install them yourself, but it’s not the simplest DIY job so if you have limited experience with air conditioners and dehumidifiers, then I would recommend hiring a professional.

However, if you are feeling confident, then this article should guide you through the whole-house dehumidifier installation process so you can have a healthier and more comfortable living space.

Josh Mitchell

Josh Mitchell

My name is Josh and I am obsessed with DIY and improving my family home. HVAC topics can be tricky for homeowners so I decided to share my knowledge on the subject. When I am not working on DIY projects, you can find me at the beach or my local coffee shop.