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Community and Q&A

Electric clothes dryer unventing

Jerry Liebler | Posted in Energy Efficiency and Durability on

Regrettably in the US there are NO vent less heat pump clothes dryers. Obviously simply not venting would cause unacceptable heat gain and really bad humidity gain. However, With a small hack on essentially any conventional electric dryer it’s inlet air supply can be collected to a single duct, it’s outlet is already in a duct. Now these two ducts can be routed to a “passive” HRV, mounted above the dryer in the laundry room, ( a passive HRV has no fans) and the other two ports of the HRV simply left open to the room. The drain lines from the HRV would be routed to the laundry sink. The hot wet output of the dryer will be cooled and dehumidified by preheating the air flowing into the dryer. Because both processes are imperfect I’d still expect the indoor air would rise in temperature and humidity but none of the energy would be vented. Some of the energy used would be recovered by preheating the air going into the dryer so fewer watts should be used but the efficiency would still be well below what a heat pump could do. Drying times may be lengthened slightly. Lint will require more maintenance than a typical HRV. I see no way of predicting how bad it’ll be. NU-AIR makes what looks like a suitable passive HRV model NU120-2 The NU-AIR has a filter for one air stream, I’ll connect that port to the dryer output and see how effective it is, I’d start by checking and cleaning the filter after each load. Hopefully the core will be largely self cleaning as the condensed water caries what is missed by the filter. I’m ready to try it! If i didn’t live in such a backward country I would rather just buy a heat pump dryer as any European can. Has anyone tried it? See any serious problems?

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  1. GBA Editor
    Martin Holladay | | #1

    Your hack won't save enough energy to be worth the hassle. And the lint is a deal-killer. You would be opening up this gadget and cleaning it every other day.

    Here's an article about clothes dryers: Alternatives to Clothes Dryers. If you don't like venting your dryer, you might consider buying a condensing clothes dryer.

  2. Rich Cowen | | #2

    I think the dryer is ripe for redesign. put the main (or a secondary) lint filter directly on the bottom where the air would come out near the center of the unit. The owner would pull the filter out after every use just like we do now. Then have a bidirectional vent that can be adjusted to sending 0% of the air out the front of the unit and all out the back (vent to outside) all the way up to 100% of the way out the front of the unit and 0% venting to outside. It could even be a smart vent that would keep the energy in your house if the humidity level is below like 40%, do a 50 50 split at 40 to 60%, and then direct it 100% outside when humidity is over 60. The cost is expensive if people have to hack their dryer but it would not be if it was built into the dryer design by a large green friendly manufacturer.

    1. Expert Member
      Deleted | | #3


  3. Jeff Wasilko | | #4

    No need now that ventless heat pump driers are available in the US.

    1. Rich Cowen | | #7

      Jeff what is the model of the ventless heat pump dryer that is out and does it temporarily chill the room at all?

      1. Jeff Wasilko | | #8

        Miele has a full line out now:

        Ours doesn't really change the room temp at all--we've got the washer and dryer installed in a small bathroom.

  4. DCContrarian | | #5

    For some reason Rich Cowen is going around resurrecting threads from almost a decade ago.

    1. Deleted | | #6


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