Humidifiers and Dehumidifiers - Aprilaire 1700 drain problem

I have a question about my aprilaire 1700 dehumidifier. It has been in service for about 2 years with no problems. All at one time, the drain is not working properly, although nothing has been changed. The drain goes from the dehumidifier, through the trap as described by the instructions and then to a condensation pump where it the water is pumped to the house drain. All has worked fine for a couple of years.

Friday, I happened to open the equipment door to the unit and found water pouring from the bottom of the unit instead of going through the drain. I assumed the drain was clogged, so I blew air through it and then pushed a tube through the drain all the way to the collection tray at under the condenser coil. I made sure the drain was completely clean. It still did not perform right, so I dismantled the dehumidifier cabinet and removed the conderser coil and compressor togeather, so I could get to the actual collection tray. I completely cleaned the tray and made sure there were no cracks or leaks and again completely cleaned the drain line through the the trap and ll of the way to the condensation pump. Everything worked fine for about 24 hours and then tonight I found water running from the bottom of the unit again.

What am I missing? There appears to be no leaks or stops, but it loses the ability to push the water through the trap and on down the drain. I know it is all gravity fed until it reaches the external condensation pump, but I also know the trap is suppose to remain full of water. Can the problem be related to the trap?

Any help would be appreciated.

As a follow up to my original question, concerning the drain on the Aprilaire 1700 dehumidifier, I have a bit more information. It appears the collection tray fills up and lets the water pour out in the bottom of the unit instead of going through the 3/4 inch drain line. Of course the logical assumption is the drain line is stopped, but that is not the case. Apparently, the trap that is placed on the drain line immediately at the exterior of the unit gets an air block. Since the drain is strictly gravity fed, there is no pressure to push past the air block.

I can pick up the flexible line on the outbound side of the trap, which apparently burps the line, and the water will immediately drain. However, after a period of time it will build up another air block and again run over from the collection tray.

The instructions say to install the trap where the drain line exists the unit. They also say the trap must be full of water when installed. I have made sure that is the case, but it makes no difference. The really odd part is the unit has worked fine with this drain arrangement for at least 2 years. There has been no change in the unit, the orientation of the line, or any other circumstance that would change the drainage capabilities. It just quit working properly.

I have cleaned the line completely to the collection tray, cleaned the tray and refilled the trap. It will work for a couple of hours and reblock.

Does anyone know if the trap is there just to prevent bugs or something gaining access to the unit and stopping up the line, or is it there to create some sort of syphoning action that is not occurring properly? Any help would be appreciated. This thing is driving me crazy!!

Handy Man,

I have the same unit and had the same problem. You are right the trap does perform a syphoning function. In my case I was using 3/4 inch tubing (1/2 inch ID) to run the condensate to the sewer. The 1/2 inch was too small to overcome the vacuum of the unit. Once I removed the restriction caused by the tubing all ran fine. Make sure that your flexline has adequate diameter or is not collapsing and restricting the flow.

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