Air Handler Sweating – How to Stop It and Why it Happens

Air Handler Sweating – How to Stop It and Why it Happens
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For stopping air handler sweating successfully, the first thing you have to do is to find out the correct source of the sweating- I mean the component due to which it is sweating. Also, you have to be convinced about the fact that somehow at the source, humid air is coming into contact with cold metal.

Causes and Remedies

  • Improper or No insulation of Ducts: The simple physics behind sweating is: “Whenever there is a contact between the hot humid air and cold metal surface then there will be sweating or condensation on the metal surface.” So, it is very important to have a proper insulation for the air handler ducts in case the portion of the duct is coming in contact with the unconditioned air outside.
  • Sealing the Crawl Space Properly: If you have the air handler unit mounted at the crawl space of your house, then sealing the crawl space properly in order to prevent the humid outside air and/or ground moisture coming inside will definitely help you reduce/eliminate the sweating problem.
  • Trying a Dehumidifier: If the outside relative humidity is too high in your area, then probably you will have to install a dehumidifier at your crawl space to get rid of the problem.
  • Air Flow: Due to the chocked filters, or blocked duct, or maybe for whatever reason, if the air flow is restricted, then there will be chance of sweating. As the air flow is reduced, the temperature of the air goes below the dew point and causes sweating. So, you may think of changing the filters or cleaning the air handler ducts to solve the problem.
  • Icing of Evaporator Coils: The ice deposition over the evaporator will cause the temperature to decrease locally at air handler unit and may cause the sweating.
  • Leakage of Ducts: The leakage of the cold air from the duct will increase the chance of sweating. You should be able to detect a visible leak by placing your hand there, or else you can get help from a set of pressure gauges.
  • Blockage of the Air handler Drain Pipe: If the air handler drain pipe get chocked and/or if the inclination of the unit is not right then the chilled water inside will be staying inside for longer and will cause the outside air to sweat over the surface of the air handler unit.
  • Temperature Setting: For each relative humidity (RH) value there is a temperature value below which the condensation will start. If you set the air conditioning temperature higher, then the temperature of the return air will also be higher and there will be less chance of sweating at the AHU.

No Solution Yet?

If you still have the air handler sweating problem, then either the source of the problem is not easy to find out or the solution is too technical to the scope of this article – time to call up the technician.


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