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Photograph of  improper condensate drain connected to plumbing vent line Air Conditioning Condensate Pumps

Types, Location, Piping, Installation

  • POST a QUESTION or COMMENT about the installation, inspection, troubleshooting & repair of air conditioner condensate pump systems used to remove HVACR condensate

Air conditioner condensate pump guide.

This air conditioning repair article discusses the inspection of air conditioning condensate pumps & condensate pump control systems, including their proper installation.

This is part of our installation, inspection, & troubleshooting guide for condensate piping, traps, drains, condensate pumps, and the detection and hazards of air conditioning system condensate leaks in buildings.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

- Daniel Friedman, Publisher/Editor/Author - See WHO ARE WE?

Condensate Drain Pump Installation & Repair

Photograph of an A/C condensate pumpAir conditioner / heat pump, or other condensate pumps are a convenient way to collect and dispose of the condensate produced by an air conditioning system when the air handler/cooling coil are located in a building location where the cooling condensate cannot be drained away by gravity.

The most common situation is the need to dispose of air conditioner condensate produced by an air handler which is installed in a building basement or crawl space.

Article Contents

How an Air Conditioner Condensate Pump Works

Air conditioner condensate is water removed from the building air as that warm, moisture-containing air moves across the cooling coil in the building's air conditioning system's air handler or blower unit. The photograph shown here is of a common air conditioner condensate disposal pump.

It's a little hard to see the pump's drain tube but it's that clear plastic tube in the upper left of this photo. If you are really alert you may have noticed those two capped-off copper tubes protruding from the concrete floor in the foreground of this photo.

This pair of tubes is a convincing indication that there was an oil tank, probably a buried oil tank, installed at this property - a topic that needs further investigation. See OIL TANKS, our oil storage tank information article, for details on that topic. Don't let our focus on any individual building concern make us miss another, possibly important discovery.

The air conditioner condensate pump photo at the very top of this page shows an air conditioning condensate pump installed in an attic where it was used to move condensate across to a final condensate disposal point.

The white piping is a gravity drain that moves condensate from the attic air conditioner air handler down into the condensate pump reservoir.

We can't see much of the condensate reservoir because the installer placed this pump down into the attic floor (so that she could drain condensate into it by gravity).

The copper tube looping in the air is the drain line through which the condensate pump is moving condensate out of its reservoir to a disposal point. You can also see the black electrical wire bringing power to the condensate pump. The black round motor with a white label is the motor that powers the condensate pump.

The black rectangular device is a voltage transformer that converts the building's 120V to the voltage needed by the pump motor.

In the background of this interesting photograph ,we see a blue sump pump with a green garden hose connected to it. We surmise that the owner had previously tried to use this sump pump to remove condensate from the attic air handler. Stains suggest that the attic floor has previously been wet by air conditioner condensate spillage, perhaps leading to the more careful condensate pump installation shown here.

Sequence of Steps in the Operation of an Air Conditioner Condensate Pump

  1. Moisture laden warm air moves across the cooling coil

    in the air conditioner. As the air is cooled, moisture leaves the cooler air and condenses on the surface of the cooling coil.
  2. Moisture on the surface of the cooling coil drips 

    into a collector tray inside the air conditioner's air handler or blower unit
  3. Moisture, or now we'll call it water or air conditioner condensate, flows 

    out of the collector tray into a drain opening and downwards in a pipe or perhaps a flexible tube where the water is conducted to the entry opening of an air conditioning condensate pump unit.
  4. The air conditioner condensate pump includes a small water reservoir 

    which receives the condensate from the air conditioner.

    As the water level rises inside this small reservoir a float switch located there is lifted by the rising water.
  5. When the water level inside the air conditioning condensate pump rises to a nearly full level,

     the float switch turns on a small electric motor (the air conditioner condensate pump requires electricity to work and has to be plugged in).
  6. The air conditioner condensate pump motor and pump move water out

     of the air conditioner condensate pump reservoir upwards in a drainage pipe or tube, usually flexible plastic tubing.
  7. The air conditioner condensate pump drain tube conducts the water

    produced by the system upwards to a building drain or in some conditions, outside, where it is disposed of as wastewater.

Proper and Improper Places to Route and Connect an Air Conditioner Condensate Pump Drain Line

Here is an excerpt from the Uniform Mechanical Code pertaining to the disposal of air conditioning condensate: "Section 310.0, 310.1 Condensate Disposal.

Condensate from air washers, air cooling coils, fuel-burning condensing appliances, the overflow from evaporative coolers and similar water supplied equipment or similar air conditioning equipment shall be collected and discharged to an approved plumbing fixture or disposal area.

If discharged into the drainage system equipment shall drain by means of an indirect waste pipe.

The waste pipe shall have a slope of not less than 1/8 inch per foot (10.5 mm/m) or one percent slope and shall be of approved corrosion-resistant material not smaller than the outlet size as required in either Section 310.3 or 310.4 below for air-cooling coils or condensing fuel-burning appliances, respectively.

Condensate or waste water shall not drain over a public way.

To clarify, an indirect waste pipe is something that is upstream of a trap. That means we cannot dump into anything downstream of a trap. That would include the main plumbing vent stack - a common error in disposing of air conditioner condensate in attic installations. [Thanks to Al Carson, Carson Dunlop Associates, Toronto]

Acceptable methods to dispose of air conditioning condensate from a condensate pump

Air conditioning condensate drain connections which are not recommended or are not best practice

AC Condensate drainage spilling onto and across a sidewalk (C) Daniel Friedman at InspectApedia.com

Photograph of an ineffective condensate drain system - a bucket

Where do I attach a condensate pump?

AC condenate drain line & othre AC/Heat pump indoor unit piping identification (C) InspectApedia.com Todd NQuestion: Where do I attach a pump to?

Can I go and buy one and install my self the condensation pump at lowes?

My unit shuts off as the drain fills with water they want 500 plus to install fro ac guy was trying to do it myself. Todd Neidhardt

Moderator reply:

Todd

Your HVAC system shows a condensate drain exiting the unit at its lower right (as sits in your photo), crossing along the bottom with some slope (as it should), teeing into a small cleanout fitting with a black cap, and continuing into a drain that exits the photo at lower left.

But

Watch out: it seems to me that you already have a condensate drain installed. It is quite possible that your system is shutting off because that drain is clogged.

When an air handler is installed without a condensate overflow pan below the unit, instead the building may be protected from condensate leak damage by a switch inside the air handler.

When that switch, sitting on the air handler bottom, senses water filling the internal condensate pan, it shuts off the unit to avoid leak damage.

So if that's happening, the proper repair is to find and fix the clog in the existing condensate drain line.

If you need a condensate pump to lift the condensate to a disposal location, that is, if your drain doesn't already dispose of condensate to an acceptable location, you'd let that drain (shown at lower left) empty into the condensate pump's reservoir, then attach a tube to the condensate pump's outlet and route that tube to an acceptable drain.

Diversitech 22 ft lift HVACR Condensate Disposal Pump cited & discussed at InspectApedia.com

If you do need to buy a condensate pump, a typical pump alone, such as this Diversitech condensate pump [above], costs less than $50. U.S. and is available at HVAC suppliers, plumbing suppliers, and building supply stores like Lowes and Home Depot.

Below we show a typical air conditioner or heat pump condensate pump indoors.

AC condensate pump connection details (C) Daniel Friedman at InspectApedia.com

The condensate pump simply sits on the floor in this installation. It receives into its reservoir condensate from a drain attached to the air handler and pumps the condensate to a suitable drainage location.

Reader follow-up:

Todd said:

Can I attach the pump to the tee? What is happening is water is not being pushed out faster enough so thermostat shuts down thank you and sorry for all the questions.

Condensate drain cleanout tee (C) InspectApedia.com Todd N

Moderator Reply:

Todd,

You should first examine the entire condensate drain to be sure it's not blocked and that it slopes between 1/8" and 1/4" to its drain destination. Otherwise we're going to some trouble to add on complexity to a system that should be working perfectly well on its own.

If you find that your condensate drain cannot work by gravity, that's when you need a condensate pump.

If that's the case, you can cut the condensate drain at any convenient location, then let it drain DOWN INTO the condensate pump reservoir, and let the pump move condensate to the desired drain location

Condensate Pump High Water Safety Switch Function & Wiring

Typical HVAC condensate pump safety (overflow) switch wiring detail - Wayne, cited & discussed at InspectApedia.com

Above: a simple wiring illustration showing how the condensate pump high water safety switch is wired between the thermostat red wire and the air handler control board.

A more detailed example is given below.

Some condensate pumps include a pair of low voltage wires connected to a condensate pump safety overflow cutoff switch designed to turn off the air handler in the event that the condensate pump stops working for any reason.

Manufacturers and other sources may call this feature a

If the condensate pump is unable to dispose of the condensate draining from the air handler's cooling coil, a float switch, usually wired in series with the thermostat wires that turn on and off the air handler on a call for cooling, will shut down the blower or air handler unit to prevent a disastrous condensate overflow leak that might cause costly damage or mold contamination in a building.

To use a condensate pump safety switch to shut down an air handler completely, the pump's safety switch low voltage wires are connected to the thermostat wires coming from the room thermostat to the air handler's control board, as we will explain in detail here. In summary:

In essence you've interrupted the red thermostat wire between thermostat and air handler control board with the wires or terminals for the condensate pump safety switch so that if that switch opens it will turn off the air handler.

If your condensate pump safety switch also has an ALARM terminal, that connects to a separate audible alarm to tell building occupants that the condensate pump has shut down their air conditioner or heat pump.

This condensate pump safety switch feature is not always used, and other methods such as a condensate overflow pan with sensor or a condensate overflow pan with a separate drain are other methods to protect a building from condensate overflow problems.

Condensate Pump High Water Switch Wiring Details

Watch out: to avoid risk of shock or injury or damage, follow the instructions for your specific condensate pump and brand. You will see that the high water level switch can ONLY be wired to a Class II low voltage circuit.

These low voltage wires will be small in diameter and may be black in color. Never connect these low voltage wires to a line voltage (120VAC or 240VAC) circuit.

Keyed to the illustration above, using the Little Giant VCMA CONDENSATE PUMP MANUAL [PDF] as an example, here above is the wiring diagram and below the wiring instructions for the high water safety switch wiring.

Watch out: Note that the terminal names and wiring details vary among condensate pump safety switches so be sure to read the instructions for your specific condensate pump brand and model.

Little Giant VCMA Condensate pump high water safety switch wiring adapted, cited, discussed at InspectApedia.com

Two options for connecting the high level switch on a condensate pump

  1. Shut Down the Air Handler: The switch is factory wired to the NO and COM terminals.

    This will open (break) a low voltage electrical circuit when the switch is activated by a high water level in the reservoir.

    This can be used to stop the condensing unit(s) of the heating/cooling system.

    Refer to the thermostat and heating/cooling unit’s Operating Manual for expected switch operation and wiring connections.

    Connect the switch leads (7) in series with the thermostat circuit as specified in the manual.
  1. Sound an Alarm: The switch can be reconfigured to the NC terminal to close a low voltage circuit

    in the event of high water level, activating an external alarm or relay (purchased separately).

    Use the following procedure if an NC configuration is required:

    Remove the pump’s motor cover (4).

    Support the switch and carefully change the lead from the NO terminal to the NC terminal (3).

    Re-install the motor cover.

    Connect the switch leads in series with the low voltage external component as specified in the component’s manual.

    Place the included “Attention Service Technician” label in a visible location.

- Little Giant, Franklin Electric Co, Oklahoma City OK, 73157-2010 USA Tel: 800-701-7894, Web: littlegiant.com

 

Condensate Tray Sensor Switch Problems

Photograph of a float switch

Reader Question: Bad condensate sensor switch shuts down the air conditioner system

One of the condensate switch went bad, thereby shutting down the system.

I have to jumpered the A/C line (yellow) to the hot (24 volts-red) on the ignition board to get the system to come back on while shopping for a new switch or pump.

I set the condensate pump to "continuous run" as a temporary measure to prevent flooding, but risk burning out the motor to the condensate pump. - Yaga

Reply:

Yaga

Watch out: there are serious risks from condensate leaks into a building if you bypass or "hot wire" the condensate overflow tray sensor switch.

Those include: condensate leak overflow, building damage, and expensive and unhealthy mold contamination or damage, electrical short circuits if wiring gets wet, and probably other hazards I've not thought of.

Condensate Pump Operating Temperature Range

Question: maximum water temperature that can pass through the condensate pump

2016/07/20 Anonymous asked:
What is the maximum water temperature that can pass through the condensate pump. I have a Honeywell true steam humidifier that needs to be emptied and the maximum temperature gets to 140F.

Reply:

Condensate pump temperature range

Anon: a typical HVAC condensate-handling pump can accept a maximum water temperature of 40oC / 104oF (Aspen pumps) or in some cases up to about 140F° (Diversitech pumps)

But there are other pumping systems designed for use with heating boilers or steam condensate that might better suit you. For example an Aspen (brand) hot water / condensate pump can handle temperatures to 80oC / 176oF.

What else goes wrong with air conditioning condensate pumps

Photograph of a damaged A/C condensate pump

In our experience these little devices are pretty reliable and useful. But a few things do go wrong, some more often than others.

Condensate Pump Manuals, Sources, Types

Mars 24 foot lift HVAC condensate disposal pump cited & discussed by InspectApedia.comCondensate removal pumps vary not only in cost but in construction materials (plastic, aluminum, other), lift capacity, pumping rate, reservoir size, condensate pump motor horsepower, and supply voltage.

Here are some condensate pump sources that include higher-temperature handling pumps for hot condensate, higher-lift condensate removal pumps and commercial grade heavy-duty condensate removal pumping equipment.

HVAC condensate lift or disposal pumps are widely sold at plumbing suppliers, HVAC suppliers, some electrical suppliers, and at building supply stores such as Home Depot, Lowes and Menards.

Illustration: The 21780 Mars Condensate Removal Pump with Safety Switch 24' Lift 125 GPH 115 Volt.

[Click to enlarge any image]

Mighty pump can be sued to un-block a clogged HVAC condensate drain line - cited & discussed at InspectApedia.com

Typical HVAC condensate pump safety (overflow) switch wiring detail - Wayne, cited & discussed at InspectApedia.com

Above: a typical wiring diagram for a condensate pump safety switch, excerpted from Wayne's manual cited below.

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