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HVACR316 - Piping

Condensation Piping and InstallationDrain Pans

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Condensation Piping & Installation• The drain line of the system must be

able to handle the water flow that is generated by the removal of moisture from the air.

• All air handlers are equipped with internal drain pans and female pipe connections to which the field installed drain line is to be connected.

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Condensation Piping & Installation• The drain line that is run should be the

same size, or larger than the fitting provided with the system. For example, if the unit is equipped with ¾ inch female pipe thread connection at the unit, under no circumstances should the size of that line be reduced. The line size is determined by the system manufacturer and should not be altered.

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Condensation Piping & Installation• In areas of extremely high humidity, the

line size can be made larger than the system design warrants. Common sense dictates that larger units will require larger condensate lines. For example, a 2.5 ton air conditioning system will produce on average 1 gallon of condensate per hour, while a 5 ton unit will produce about 2 gallons of condensate per hour. Under no circumstances should a drain line be less than ¾ inches in diameter.

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Condensation Piping & Installation• Drain line material should be

constructed of materials that are in accordance with local plumbing codes. Normally, PVC piping is acceptable for most residential applications.

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Condensation Piping & Installation• When the condensate line is to be

located within a concealed wall or ceiling, it is recommended (and sometimes required) that copper be used.

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Condensation Piping & Installation• When installing a PVC condensate drain

line, all fittings and pipe ends should be cleaned first with a PVC primer, and then joined using PVC cement .

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Condensation Piping & Installation• Using cement that is not designed for

use with PVC pipe can result in a weak joint that may leak in the future.

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Condensation Piping & Installation• When installing a copper drain line, all

solder joints must be checked for leaks before the system is put into operation.

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Condensation Piping & Installation• The condensate line should always be

pitched toward the termination point of the line.

• The minimum pitch on the line should be ¼ inch per 1 foot of horizontal run For example, a 10 foot horizontal drain line should be pitched a minimum of 2.5 inches.

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Condensation Piping & Installation• Drain lines should be adequately

supported to ensure that the proper pitch is maintained. To facilitate proper draining of the condensate, the pitch should be made as great as possible.

• Improperly pitched drain lines can result in water damage to both the system and the structure.

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Condensation Piping & Installation• The condensate that is removed from the

system must be deposited in a location that is not objectionable to the occupant of the occupied space. This is commonly either outside the structure or down a waste line.

• If the unit is located in an attic or a closet, the drain line usually leaves the structure through the same building penetration that the refrigerant lines and low voltage wiring will pass through.

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Condensation Piping & Installation• The drain line should be as short as

possible, to reduce the possibility of a blockage that would cause the line to back up and cause damage.

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Condensation Piping & Installation• If running the line to the outside of the

structure is not possible, the line should be run to a nearby waste line or utility sink. All local codes regarding the installation of drain line should be followed.

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Condensation Piping & Installation• When the indoor unit is located in the

basement, the unit is below ground level and a gravity type drain is not possible, two other options are available: – Use a floor drain – Pump out the condensate

• If the unit is installed in an unfinished basement and a floor drain is nearby, the condensate should be directed toward it.

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Condensation Piping & Installation• The line should be run from the unit,

along the floor of the basement, making certain that the line is secured so the water is directed to the drain. Before the system is started up, the floor drain should be tested to be certain that it is still operational.

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Condensation Piping & Installation• If a floor drain is not available or if the

basement is finished, the condensate may need to be pumped from the location.

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Condensation Pumps

• A condensate pump may be used to remove the water. The pump is normally in the off position and is controlled by a float switch. Once the water in the pump’s reservoir reaches a predetermined point, the pump switches on, removing the water. When the water level is lowered, it switches off.

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Condensation Pumps

• The pump is located close to the unit, and the water is pumped either outside or to a utility sink for disposal.

• The piping run from the unit to the pump is therefore very short. The need for a trap is determined by the configuration of the unit.

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Condensation Pumps

• Some condensate pumps are equipped with an overflow control. This will prevent water damage from occurring if the pump should fail. This overflow control is a normally closed switch that will open if the water level rises above the maximum level permitted by the pump.

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Condensation Overflow

• If a problem arises with a drain line, such as a blockage, the condensate cannot be carried away from the unit. This would lead to an overflow condition and could result in water damage.

• Preventive maintenance could help prevent the drain line from getting clogged, but this occurrence cannot be predicted.

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Auxiliary Drain Pans

• One way to effectively eliminate the possibility of water damage from overflow is to install an Auxiliary Drain Pan under the unit to catch and remove any overflow condensate.

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Auxiliary Drain Pans

• The pan should be large enough to catch the water leaking from anywhere in the unit. Prefabricated plastic drain pans can be purchased in a wide range of sizes. Pans can be made of sheet metal, as long as the corners are sealed to ensure that the pan will hold water.

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Auxiliary Drain Pans

• The auxiliary pan should be mounted securely under the unit in the event it actually has to hold water. In an ideal situation, this pan should remain perfectly dry at all times.