Condensate Pump Running Continuously (What’s Wrong?)

Is your condensate pump running continuously and you don't know why?

If a condensate pump runs all the time, it can burn out the motor, and may even cause water damage to your home.

In this guide, I will go over...

  • How to inspect the check valve and pump
  • Why a stuck float is a likely culprit
  • And how to inspect the flexible discharge line

Let's get started with this guide!

condensate pump running continuously

Why Is My Condensate Pump Running All The Time?

The big problem with a condensate pump that is running continuously (or constantly turning on and off) is that it can burn out the motor.

And if your condensate pump motor breaks down, and if you don't have a water alarm, or if you are on vacation — then serious water damage may happen to your home — especially if it's on an upper level. When you have water damage, you have the potential for mold growth.

If your condensate pump is running continuously, then you may either have problem with the discharge line, the check valve, or the pump itself. It may be a defective part, or it may be a clog. The first step is to check that water is properly leaving the flexible discharge line, and then I would inspect the check valve, and lastly look at the pump itself (especially the float switch).

Read the rest of my guide for the details on how to inspect a condensate pump....

Read Also: What Are The Best Rated Condensate Pumps?

#1. Check The Discharge Line

The first place I would check to see if there is a problem is the discharge line — which is usually clear vinyl tubing. This is the small 3/8-inch flexible tubing that goes from the top of the condensate pump and discharges the water to the exterior or to a distant floor drain.

It's important to first unplug the condensate pump before you begin inspecting it — you don't want to get shocked.

Simply pull the discharge tubing out with a little pressure, it is likely just held using the plastic barbs of the check valve.  If there is a hose clamp, you will need to remove it.

If there is still water in the discharge line, drain the existing water into a bucket.

Once all water is drained out, try blowing on the discharge line. If the you can't blow freely through the discharge line, then you know there is some type of clog or obstruction in the line.

You can follow the line to the exterior (while still inside) and see if you notice any problems. And then go outside and find the termination of the discharge line, and see if there are any problems.

Read Also: How To Tell If Your Condensate Pump Is Working?

condensate pump running continuously (1)

#2. Inspect The Check Valve

The check valve is a small plastic one way water valve that connects to the discharge line. The check valve prevents flow in the wrong direction. It allows water to only towards the exterior (and not back into the pump).

check valve

Check Valve

If any remaining water in the discharge line remains after the pump stops, the check valve will prevent this water from going back into the condensate pump (and turning it back on). It basically prevents harmful short cycling of the condensate pump.

Before you test the check valve, it's a good idea to do this step on a deck or somewhere on the exterior. You will have to remove any screws that may be securing the condensate pump to a wall (or it may be loosely on the floor) as well as removing the 3/4" pipe (white PVC) from one of the inlets. This rigid PVC pipe is the drain pipe from the air handler.

Once the pump is outside, pour some water into to one of the inlet holes if the pump isn't already full of water.

And now plug in the condensate pump into a GFCI outlet (exterior outlets should be GFCI).

The pump should automatically turn on, and water should start pumping out of the check valve in a strong stream, shooting upwards around two feet. If the stream is weak, such as a dribble, then you know the check valve is defective or clogged.

To remove the check valve, you simply use a small wrench or socket to loosen the check valve. The valve is threaded and has a small rubber O-ring.

Once you have the check valve in your hand, you can use a few Q-tips to remove any debris in the check valve.

Or you can simply buy a new check valve for a few bucks on Amazon, such as the this Little Giant Check Valve.

#3. Look At The Pump

If the check valve is working properly, and shoots out a strong stream of water, then you can move on to evaluate the pump.

To remove the cover of the condensate pump, there should be a small clip on the side that you lift up. After you have removed the cover, carefully inspect the float, the part that moves up and down that activates the pump.

Is the float operating correctly or is it stuck? But if the pump is turning on and off frequently, then it isn't the float.

Also, check the inlet holes in the pump to make sure it isn't clogged.

Just remember that if water is pumping correctly out of the tank, then it is likely a stuck float problem. If there is no water coming out, then there is likely a clog either inside the condensate pump (after checking discharge line and check valve).

If you still don't see anything wrong, your condensate pump may be just undersized for the height and horizontal length of the discharge line — especially if the line height is 15-feet or more. You may need to get a stronger pump so it will empty the tank quicker rather than running continuously.

Read Also: What Are The Best Washable HVAC Filters?

#4. Turn Off The Whole House Humidifier

A whole house humidifier is a device mounted on the HVAC duct next to the furnace. You can read my guide on the best whole house humidifiers here. Whole house humidifiers turn on when the heat is on, and when the humidistat is below the target humidity level.

If you have a humidifier, it's a good idea to momentarily turn it off, and see if the condensate pump still runs continuously. If turning off your whole house humidifier solves the problem, then the issue is with the humidifier.

The humidifier should only turn on when the furnace is actually on  — you may want to verify that it isn't on even when the furnace is off.

If the humidifier turns off when it should, and you don't see any other problems, then the condensate pump may just be undersized, and not pumping out water quickly enough — especially if the discharge line height is very high.

Read Also: MERV Vs. MPR Furnace Filter Ratings

What Is A Condensate Pump?

A condensate pump is a small water pump that discharges water directly to the exterior or to a distant floor drain.

The most common use for condensate pumps is to drain air conditioning systems, high efficiency furnaces, and whole house humidifiers. AC systems pull out moisture from the air, dehumidification is part of the A/C process, and all of this water needs to go the outside. And if your system doesn't have a nearby floor drain, a condensate pump is used to pump it directly the outside or to a farther away floor drain.

If your condensate pump is running continuously, then there are a few possibilities as what is broken.

Read Also: What Are The Best Furnace Filters For Dust Control?

Final Thoughts

If your condensate pump runs continously, then it is likely a problem with either the flexible discharge line, the check valve, or the pump itself.

It may be a defect or it may be a clog.

And lastly, after inspecting everything, and you don't find a problem, then the problem may be an undersized condensate pump if the discharge line is very long or has to travel up a large vertical heigh.

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Arie Van Tuijl

Arie Van Tuijl

Arie is the founder of Home Inspector Secrets, an online resource dedicated to helping people understand how homes work. He is a licensed home inspector in two U.S states and owns a residential and commercial inspection company (read his full bio on the About page). To ask Arie a question, please use the comment box at the bottom of the relevant article.

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Home Inspector Secrets is an online resource for owners, buyers, and sellers to understand all aspects of home maintenance. We have detailed home guides, product reviews, inspection advice, and much more.