The short answer
A condensate pump is the small box with a tank that sits next to a furnace or air handler. A high-efficiency furnace makes water every time it runs, and so does an air conditioner, and when there’s no floor drain lower than the equipment, this pump lifts that water up and out through a thin tube. In a Northern Virginia basement it usually fails one of three ways: water on the floor, the furnace or AC shut off by its safety switch, or a pump that runs and won’t stop. Most of the time slime has clogged the float or the check valve, and a rinse fixes it. A pump with a worn motor gets replaced.
What each sign means
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| What you see or hear | What it usually means | What to do first |
|---|---|---|
| Water on the floor by the pump or the furnace | The pump didn’t empty its tank: a stuck float, a dead motor, or a tube that’s kinked, clogged or frozen | Look in the tank. Full of water with the pump silent is the float or the motor. |
| The furnace or AC shut off, and the tank is full | The safety switch did its job. It turns the system off before the water reaches the floor. | Empty the tank and find the cause. Never wire around the switch. |
| Beeping | Some pumps, and add-on alarms, beep when the water in the tank rises too high | Same as a full tank: check the float and the tube. |
| It runs every few seconds, or won’t stop | The check valve lets the water in the tube fall back into the tank, or the float is stuck up | Watch the tank right after it pumps. If the water jumps back up, it’s the check valve. |
| A rattle or a grind | A worn motor, or a pump sitting crooked and buzzing against the furnace | Set it level and on its own. A grinding motor is near the end. |
| A drip from the tube | A cracked tube, or one that slipped off the pump’s outlet | Push it back on or replace the tube. |
The $67 Heating Check
We check your furnace, heat pump or boiler before winter. Through December 31. See the offer
Why condensate pumps fail
- Slime. The water sits in a dark, warm tank, and a slimy film builds up on the float and in the check valve. It’s the most common reason a condensate pump quits.
- A stuck float. The float rises with the water and switches the pump on. Slime, or a pump that’s been knocked crooked, keeps it from moving.
- The check valve. It keeps the water in the tube from running back into the tank. When it sticks open, the pump lifts the same water over and over and wears out early.
- A worn motor. These are small pumps that run many times a day, for years. When the motor goes, the pump hums or goes quiet.
- A frozen or blocked line. If the tube runs outside, it can freeze on a cold night. A tube that’s kinked behind the furnace backs the water up just the same.
- Acidic water. The water a high-efficiency furnace makes is mildly acidic, and over the years it wears on the pump’s parts.
What you can check yourself
- The power. Make sure the pump is plugged in and the outlet works. If it’s a GFCI outlet, press reset.
- Unplug it, then empty the tank. Most come apart with a couple of clips or screws. Pour the water out, then rinse the tank and the float in warm, soapy water until the slime is gone.
- Test it. Put it back together, plug it in, and pour water into the tank. It should switch on, pump the tank down and stop.
- Follow the tube. Trace it from the pump to where it ends: a sink, a drain or outside. Look for kinks, a low spot holding water, and ice at the outside end.
- Leave the safety switch alone. The two thin wires running from the pump to the furnace or air handler are what shut the system off before water reaches the floor. Wiring around them to get the heat back on trades a cold night for a wet basement.
Can the furnace run without it?
Not for long. A high-efficiency furnace makes water every time it runs, and on a cold day it runs a lot. With the pump dead, the safety switch shuts the furnace off, or the water ends up on the floor. If there’s a floor drain lower than the furnace’s drain line, the line can sometimes run there on its own and skip the pump. That’s worth asking about at the visit.
Clean it or replace it?
A pump that runs after a rinse and pumps its tank down is fine. Rinse it again each fall. One that hums, runs hot, won’t start after a clean-out, or has a cracked tank is done.
Our condensate pump replacements have run $450 to $500 installed on our jobs this year, parts and labor: a new condensate pump at the furnace or air handler, wired to the safety switch that shuts the system off if the water rises, the drain line connected, and tested by running water through it.
When the pump isn’t the problem
The furnace has its own condensate drain and trap before the water ever gets to the pump, and that part clogs and freezes too. Our guide to a clogged or frozen furnace condensate drain covers it, and the condensate overflow switch video shows the safety switch that shuts things down. A furnace that starts and stops over and over has other causes too, in furnace short cycling. A pump that rattles is one of the sounds in what house noises mean.
Before the cold sets in
If the furnace hasn’t had its fall check yet, our heating check is $67 per system, through December 31: furnace, heat pump or boiler. Book it from goswiftpro.com/cookiesoffer by November 30 and a box of warm MOLTN cookies comes with it.
Book it
A repair visit starts with a flat $99 diagnostic, or $250 after hours, and you get the price of the fix before we touch anything. Call (703) 997-9757, day or night, or book online with the problem already filled in. Every current deal is on our offers page. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
Why is my condensate pump leaking?
Usually the pump isn’t emptying its tank: the float is stuck in slime, the motor failed, or the tube out is kinked, clogged or frozen. Water can also drip from a cracked tank or a tube that slipped off the outlet. Unplug it, empty and rinse the tank, then pour water in to test it.
Why is my condensate pump beeping?
The water in the tank rose higher than it should, and the pump’s alarm or an add-on alarm is telling you. Check the float and the tube. On many systems the same switch also shuts the furnace or AC off.
Why is my condensate pump running constantly?
The check valve isn’t holding, so the water in the tube falls back and the pump lifts it again, or the float is stuck up. Rinse it. If the water level jumps back after every cycle, the check valve or the pump needs replacing.
Can I run my furnace without a condensate pump?
Not if the furnace sits lower than any drain it could empty into. A high-efficiency furnace makes water every time it runs. With no working pump, the safety switch shuts it off or the water ends up on the floor.
How much does it cost to replace a condensate pump?
Our condensate pump replacements have run $450 to $500 installed this year, parts and labor, wired to the safety switch and tested before we leave. A repair visit starts with the $99 diagnostic, and you get the price before any work.
