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WatchDog NXT85 Dehumidifier Quick Start Guide


Table of Contents

Prepare Crawl Space for Installation

Tips for Dehumidifier Installation

Operating Instructions

Benefits of a Dehumidifier

Unit Diagram

Trouble Shooting

Optional Accessories

Submit Warranty

Additional Resources

While you’re waiting for your new dehumidifier to arrive, here a few topics to keep in mind.

How to Prepare Your Crawl Space for Installation

Prepare your crawl space

If you decide to install your dehumidifier in a crawl space, there are a few steps you need to take prior to installation.

1. First, you will need clean out any debris that may be cluttering up the crawl space. This will make sure that there are no hidden problems such as cracks in the foundation. It will also ensure that the vapor barrier can be installed properly. In addition, cleaning out any unnecessary items will make it much easier to move around in the crawl space. Being able to move around more easily is useful for a hassle free installation, as well as for future maintenance that may need to be done.

2. After the crawl space is clear, you will need to inspect it for any potential issues so they can be fixed prior to installation. For instance, you may notice signs of pests or rodents in the crawl space. The crawl space could also show signs of structural issues, such as damaged floor joists or girders. Most importantly, you need to ensure that all signs of excess moisture are taken care of. This could be anything from puddles of water to leaking pipes.

If not taken care of prior to installation, these issues could prevent your dehumidifier from running effectively. Consequently, if you discover any problems be sure to either repair them yourself or call the necessary people to take care of them.

3. Once the issues have been repaired, it’s time to to seal the openings in the crawl space. If your crawl space is not sealed properly, your new dehumidifier will never be effective. Everything from the ceiling to foundation vents needs to be properly sealed. To quickly test if your crawl space is completely sealed, complete the following test. First, close the access door, then turn of all of the lights. Once that is done, check to make sure that no light is coming into the crawl space.

4. The final step in preparing your crawl space is to install the vapor barrier. A vapor barrier is a heavy duty plastic sheeting used to keep moisture out of the crawl space. Having a vapor barrier also makes it easier to move around in the crawl space. If you want a vapor barrier that works effectively, be sure to use polyethylene that is at least 10 mil. thick. It Furthermore, be sure to overlap the seams by at least 12 inches and seal all joints with adhesive during installation.

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Tips for Dehumidifier Installation

Dehumidifier tips

To help make dehumidifier installation hassle free, here are a few tips to keep in mind.
1. As we discussed earlier, it’s important to prep your crawl space prior to installation. It’s much easier to fix the problems now rather than let them get worse. If you need a refresher, refer back to the crawl space prep section.

2. After the crawl space is prepared, it’s time to decide what area of the crawl space is best for the dehumidifier. You will need access to a 115V, 60Hz, 3-Prong GFI outlet with a 15 amp time delay fuse or circuit breaker. It’s helpful to place it somewhere easily accessible to make routine maintenance easier. Another important factor is set up for the drainage system. The NXT85 can’t sit directly on the ground until the unit is feeding directly into a sump pump next to it. Elevation is required for water to flow through the gravity drain.

3. Once you’ve located the perfect spot, you need to create a base for the dehumidifier. This could be anything from a level pad to blocks, as long as it’s a stable mounting location.

4. Now that you have the base set up, you can finally add the machine. Carefully bring in the dehumidifier and set it on top of the base. Make sure that the dehumidifier is level before proceeding.

5. After the dehumidifier is level, you need to direct the exhaust outlet into the desired location. Typically, you will want to choose the longest, unobstructed dimension in the crawl space.

6. At this point, you can set up the gravity drain. The drain line should be routed to a suitable drain on the outside. It must flow downward without any loops or dips. In most situations, transitioning from the drain line to PVC pipe is the best option. See the Recommended Gravity Drain Section for further details.

7. That’s it for installation, now you’re ready to plug in your machine and turn it on! Prior to leaving the crawl space, don’t forget to check the unit’s serial number so you can activate your dehumidifiers warranty.



Recommended Gravity Drain Option

Dehumidifier drain tube

The WatchDog NXT85 comes standard with 12” of drain line. If you need the drain line to be longer, it’s useful to transition to PVC pipe or you may have difficulty keeping the drain line unkinked.

Tools Needed:
• 3/4” OD PVC, long enough to reach your desired drainage spot
• 3/4” PVC elbow
• approx. 6” 3/4” OD PVC

1. First, insert the longer section of PVC into the elbow. (Note: Keep the length of PVC drain pipe to a minimum)

2. Next, insert the 6” section of PVC onto the other end of the elbow.

3. Finally, insert the open end of the drain line into the 6” section of PVC. Make sure the drain line will flow into the tubing, however, you don’t want it extending into the PVC elbow.

4. Support the PVC tubing as necessary, so that it can maintain a smooth, downward flow to the drain.

5. Prior to leaving the crawl space, verify that the gravity drain is working properly.



Optional Inlet and Outlet Duct* Installation

Ducting the dehumidifier allows the unit to be in one room while conditioning an adjacent room. Both the inlet/return grille and the supply grille are designed for 10” flex ducting.

1. Secure the 4 screws on each duct adapter.

2. Slide the ducting over adapter and secure with tie wrap or clamps. The maximum length for the duct is 10’.

*Inlet duct and outlet duct are optional accessories.


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Operating Instructions

Dehumidifier display board


Dehumidifier operating instructions

Turning the Unit On/Off

• To turn the dehumidifier on, press the power button. You will hear one beep as the machine starts to run. In addition, the light will illuminate red.
• Once running, the power light will illuminate red.
• To turn the unit off, press the power button again. You will hear a single beep as the machine begins to shut down process. Keep in mind that there is a one minute fan delay after shut down.

Adjusting the Settings

Humidity Level

• To adjust the humidity level, use the up arrow and the down arrow buttons until the desired level is displayed on your screen. The dehumidifier can be set anywhere between 35%-90%. The typical set point is between 50% and 55% humidity.
• Creating a desired humidity set point means that when the indoor humidity is higher than the set level, the unit will operate.

Continuous Mode

• If you need your WatchDog to run constantly, you can use Continuous mode . To switch into Continuous mode, use the arrow keys to set the humidity below 36%. At this point, the Cont. Defrost light should illuminate green on the display board to indicate the unit has been successfully switched to Continuous mode. The display screen will show “CO”.
• Once in continuous mode, the dehumidifier will run constantly regardless of the level humidity level until you turn the unit off or switch back to normal humidistat operation. If you would like to change to humidistat operation, simply press the up and down arrows simultaneously.

Compressor Indicator

• The compressor indicator will illuminate red on the display board to show that compressor operation has been initiated and the unit is currently warming up. Wait a few minutes and the compressor will begin to run. Once running, the compressor indicator will switch to green.

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Benefits of a Dehumidifier

Dehumidifier benefits

Now that you’ve purchased a dehumidifier, you will be able to eliminate many of the problems that have been plaguing your home. Here are just a few benefits that you can look forward to:

Pleasant Air Quality

Although your dehumidifier will be located in the crawl space, it will affect the air quality in your entire home. See, the moisture in your crawl space mixes with the air and naturally rises upwards through a process called the “Stack Effect”. This means that all of the moist humid, air in the crawl space is spread throughout your entire home.

Adding a dehumidifier will help reduce humidity in the crawl space, thus affecting your entire home. Once you install your dehumidifier, you won’t have to deal with a muggy, uncomfortable living environment.

Healthier Environment

Not only is high humidity uncomfortable, but it can also be harmful to your health. Living in a humid home can lead to serious health issues, especially when mold and mildew develop. Furthermore, high humidity can exacerbate current medical issues, such as asthma or allergies.

Eliminate Mold

A humid crawl space is the perfect environment for mold and mildew to spread. Mold spores spread through damp, moist areas so if you can eliminate the moisture, you can eliminate the mold. Using your new dehumidifier in the crawl space is the perfect way to remove moisture and maintain environment.

Deter Pests

Excess moisture and humidity is also very enticing to pests and bugs since they need moisture to survive. So, for instance, if there are puddles on the ground or moisture in the sub-flooring, your home will attract all sorts of pests from termites to cockroaches. By installing your dehumidifier, you can dry out the environment and discourage them in the future.

Preserving your Home

Another big advantage of installing a crawl space dehumidifier is protecting your home from damage. Long period of high humidity plus the damage from mold and pests can be very damaging for your home. Everything from the foundation to walls can begin to show signs of wear and damage.

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NXT85 Unit Diagram

Dehumidifier terms

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NXT85 TroubleShooting

Dehumidifier terms

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Optional Accessories

Dehumidifier drain tube

Environmental Monitor (W-111):
The Environmental Monitor allows you to monitor the conditions of your crawl space or basement remotely. Simply download the mobile app on your phone, plug the gateway into your wireless router, and mount the sensor with the attached probe.

Remote Control Package (W-100):
The WatchDog Remote Control package includes a remote control and 25’ of CAT-5 cable. The remote control has a built-in sensor which allows you to remotely control the unit, as well as monitor the conditions around the dehumidifier.

WatchDog NXT Return + Supply Duct Collar Assembly (N-103):
The return and supply duct collar assembly allows you to connect the dehumidifier to your HVAC or duct the conditioned air from your dehumidifier into an adjacent room.

WatchDog NXT85 HEPA Filter (N-202):
The HEPA filter is an optional accessory to replace the MERV-10 filter that comes standard in the NXT85. The HEPA filter is extremely effective at removing even the the smallest of particles from the air.

WatchDog NXT85 Carbon Filter (N-203):
The carbon filter is an option to replace the MERV-10 filter that comes standard in the NXT85. In addition to removing particles from the air, the carbon filter is designed to remove odors.

WatchDog NXT Hanging Kit (W-112):
The WatchDog Hanging Kit provides an easy way to hang your dehumidifier so it is off the ground.



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Activating Your Warranty

Once you have your dehumidifier installed, it's time to activate your warranty. All WatchDog NXT dehumidifiers include a complete 5 year warranty. In order to take advantage of this service, please be sure to submit the warranty card in your owner’s manual.


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Additional Resources

For further assistance on the operating and maintaining your new dehumidifier, visit the Literature section for the WatchDog 550.



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