• SkillCat Team

Routine Maintenance: Inspect & Clean Drainage Components

Updated: Jul 12


Routine Maintenance: Residential Systems: Chapter 6


Drainage Components


In this module, we will look at how to inspect and clean condensate drain. We will also look at how to replace the condensate pump.Skip to quiz!


Inspecting Drain Line


Recall that when the air passes through a cooling coil, moisture in the air converts into water. This conversion of moisture or vapor into water is called condensation.The condensate drain helps remove this water.


The condensate drain consists of a drain pan and a drain line. The water that drips off the cooling coil is collected in the drain pan. Then, from the drain pan, the condensate drain line moves the water out of the house.


P-trap is a curved pipe attached to the condensate drain line. Drained water is collected at the

bottom of the curve P-trap. This water creates an air seal that prevents air from outside entering the furnace. P-trap is placed near the furnace.


When we inspect the drain line, we also inspect the P-trap as it is attached to it. We do not need to separately inspect the P-trap. For inspecting the drain line, we first need to switch off the air handler. We should look around the air handler for any evidence of water.


After we look for water around the air handler, we need to remove the access panel. We then inspect the drain pan with a flashlight for leaks. We also inspect for debris and clean the drain pan if it has any debris.


Next, we check the opening to the condensate drain line for any obvious debris. We have to pour the water into the drain pan and observe the water level in it. The poured water should flow freely through the drain line. Otherwise, we have to clean the drain line.


Cleaning Drain Line


For cleaning the drain line, we first switch off the air handler. We pour the distilled vinegar in the drain line through the opening and let the solution sit for half an hour.


After that, we have to flush the pipe with water to make sure that it is clean and operating normally. Finally, we close the cap of the pipe and switch on the air handler.



Replacing Condensate Pump


A condensate pump is a device used to move and direct the flow of the condensate water to the drain line. Condensate pump has:

  • a tank, and

  • a float switch.


Tank is used to collect the condensate water. Float switch is used to turn on the condensate pump. When the water reaches the set level, the float switch will turn on the pump until the water is drained from the tank.


To replace the condensate pump, we first switch off the furnace and unplug the old condensate pump. If the pump has a safety switch, we have to disconnect the safety switch wires. Next, we loosen the mounting screws and disconnect the discharge tube.


We remove the condensate drain inlet pipe in the pump and slide the old pump out of the way. Now we have to connect the drain inlet pipe to the new pump and set the pump into place. Next, we attach the discharge tube to the pump.

If the old pump has a safety switch, then we have to connect the wires to the switch of the new pump. We have to plug in the condensate pump and turn on the furnace. Finally, we will test the pump by adding some water in the tank of condensate pump and make sure it is working properly.


The condensate drain consists of a drain pan and a drain line. The condensate line helps remove the water that drips off the cooling coil. We clean the condensate drain if it has any debris.


Condensate pump has:

  • a tank, and

  • a float switch.

We test the condensate pump by adding some water in the tank of the condensate pump and make sure it is working correctly.




Question #1: P-trap in the drain line prevents air from outside entering into the furnace.

  1. True

  2. False

Scroll down for the answer...
















Answer: True

P-trap is a curved pipe attached to the condensate drain line. Drained water is collected at the bottom the of the curve of the P-trap. This water creates an air seal that prevents air from outside entering the furnace.


Question #2: After pouring distilled vinegar into the drain line for cleaning, we have to

  1. immediately flush with water

  2. let the solution sit for half an hour

Scroll down for the answer...













Answer: let the solution sit for half an hour

Distilled vinegar takes some time to react with the debris inside the drain line. If flush with water immediately after pouring vinegar, it will not be able to clean the drain line.


Question #3: Float switch is used to turn on the condensate pump.

  1. True

  2. False

Scroll down for the answer...













Answer: True

Float switch is used to turn on the condensate pump. When the water reaches set level, the float switch will turn on the pump until the water is drained from the tank.

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