Question about DeLonghi DE400P Dehumidifier

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DH400P pump is not working, please advise, thanks.

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  • dbpactman Jul 03, 2008

    Pump stopped working. It sounds like it is when I put the pump to the on position, but still when the pan fills up the machine starts beeping and shuts down. This happens whether the pump is in the on or automatic position. I tried to blow out the line to make sure water could be pumped through the drainage tubing. It is flowing if I blow into it or by gravity. I don't know what else to do. Please advise.

  • nm156 Sep 04, 2008

    I had the same problem and followed the advise here.

    It wasnt an easy task , but I would think any one with a screw driver and memory to remember which screw went where can do it.

    You pretty much have to remove the entire cover off the unit.

    The small tank inside was filled with water and gunk. Simply remover the water, gunk , clear out the water lines , screw the cover back on your done!

    Many thanks for the advice,

    I was getting tired of emptying the tank in the middle of the night.



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I had a similar problem with the pump not working and the water flowing into the main drainage bucket instead. I had to disassemble the housing...not an easy project to reassemble...and found that the pump has its own smaller drainage tank with a float device, a pump pre-filter, the actual pump, then of course, more drainage tubes. The entire pump drainage system of components needed cleaned of accumulated, mucoid, slime! I cleaned the channel in which water flows into the pump's tank...located on the screen filter side of the dehumidifier. Then I moved to the other side of the dehumidifier and cleaned-out the entire pump drainage tank. Note that the pump's drainage tank only empties about 1/2 inch of water each time the pump activates. Thus, there is always alot of water in the pump's drainage tank. Thus, alot of time for slime to accumulate. Next, I cleaned off the float mechanism. I then cleaned-out the pump's pre-filter. Cleaning out the pump's pre-filter was paramount to the pump functioning properly and quietly! I checked that my pump was properly installed and NOT rubbing against its mounting so that it operated quietly. I added fresh water to the pump's tank several times to insure that the pump was working properly and that all slime was eliminated. Finally, I reassembled the housing...not an easy task! My pump now functions like new. All this work had to be done to insure proper function of the dehumidifier's pump system. My dehumidifier is only 11 months old. It is still covered by the one year warranty, but it is too expensive to ship the entire unit, as Delonghi requires you to do at your expense for them to fix it under warranty. You can be assured that I will check for future slime build-up to keep my dehumidifier functioning properly. The dehumidifier works great, it's just that it's high maintenance.

Posted on Jul 21, 2008

  • flybynyt Feb 23, 2011

    Here are a few pointers I would add to Ladyfixer's great instructions:
    Tools: Philips head screwdriver; 2) Turkey baster, or my favotire little tool "The Mix-Mizer" handy to **** out the mucoid slime. 3) Needlenose pliers with cutter 4) small plastic ties to re-clamp hose connnections to pump, tank, etc. 5) tight fitting rubber gloves, the kind your doctor wears. 6) Pipe cleaners.
    Once all the outer case screws were removed (some wehre flat head, some not. take notes on which screws go where), I was able to flip the outer case open like a ****-shell. Rest/balance the digital control panel wiring connections on top of the unit without having to disconnect and remove. Once visible, you can follow the water's path and easily see how things get gunked up.
    The inner tank and float design is not unlike your home toilet. Once the float level reaches a certain hight, the pump kicks-in, and sends the water uot the bottom.
    DON'T try to pull the hose connections off without cutting the plastic ties or you will likely snap off the nipples. Once the ties were cut, it was easy to remove hoses and the pre-filter-backflow preventer, which was also clogged, chocking off water flow to the pump.. **** the mucoid slime out of the inner tank. There was A LOT, and it's gross. Once removed from the unit, I soaked the filter-backflow preventer in Efferedent and hot water. Once the sludge started to break-up, use the pipe cleaner and pressurized air to force the sludge out of the little nipple openings.

  • Lynn De Marco Jun 24, 2012

    I discovered that my pump was not functioning properly for the same slime build-up reason stated above.

    A friend cleaned out the slime in the pump tank for me last year and broke one of the nipples just as flybynyt mentioned below. I didn't see the inside before he fixed it and he sealed the hole up with epoxy so I'm not sure how the entire drainage tubing setup was plumped.

    To make matters worse, I just tried cleaning it again this year and I broke off the other nipple!

    I am ordering a new pump tank but I still need to know what drainage tubes to attach to the two drain holes, and where the pre-filter-backflow preventer should be inserted in the drainage tubing.

    As I'm sure everyone knows by now, there is no repair service manual available online (that I can find, at least) for the DeLonghi DE400P, only the user manual and a parts diagram.

    Would it please be possible for someone to post either a photo of the correct pump tank and drainage tubing/pre-filter setup or draw some kind of diagram? This would be a real aggravation saver!!!



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