Electric clothes dryer unventing
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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Replies
Jerry,
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.
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.
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No need now that ventless heat pump driers are available in the US.
Jeff what is the model of the ventless heat pump dryer that is out and does it temporarily chill the room at all?
Miele has a full line out now:
https://www.mieleusa.com/e/tumble-dryers-1015698-c
Ours doesn't really change the room temp at all--we've got the washer and dryer installed in a small bathroom.
For some reason Rich Cowen is going around resurrecting threads from almost a decade ago.
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Old topic, but came up in my search.
I vented my 20-30yr old electric dryer to the basement where a heatpump water heater is semi enclosed, to recover the heat and humidity. Regardless of dryer use, the basement is nice and dry. I used a 6"x25' cheap flexible duct stretched tight, ending in an inverted plastic bucket with a cotton tshirt sewn shut as a secondary lint filter. I take the shirt outside to dump it once or twice a year, and it seems to catch most all the lint.
If the dryer ever goes, then yes I'd get a heatpump dryer. The dryer is wired to run the heater element only on 120v instead of 240v. It takes longer to dry, but the electrical load is minimal, helping to enable the house to usually run off-grid on battery & solar.
daleks,
Careful, that's a code violation (IRC M1502.3). If you ever have a dryer-related fire or other damage, that setup will void your insurance.
I've been happy with my Miele heat pump dryer in the 5 months I've had it so far. While the washer takes a little extra time to really spin out most of the water the dryer then doesn't take much longer than what I've experienced with other dryers. I bought an extra plinth filter so that when the dryer indicates a need to clean it every 2-4 weeks I can then just switch them out, rinse the old one and give it time to dry without having to delay using the dryer.
I've been looking for a spare filter....any chance you found a deal on one?
I have not found a deal on one, but I did get buy a 2nd one from the Miele website.
I bought directly from Miele to be sure it was the right one and the price wasn't bad. https://www.mieleusa.com/e/toe-kick-filter-filter-bg-9164761-p
Thanks! Not a bad price and free shipping....
I've been using a Whirpool WHD560CHW since April, I find the performance is fine. Not to damn it with faint praise, but it's unremarkable, it works as well as any other dryer. I haven't had it long enough to know about its reliability or durability. Is is a bit louder than a conventional dryer, and it does tend to heat up the laundry room.
Before that I had a Bosch heat pump dryer. It took noticeably longer to dry the clothes and about once a year I had to take it apart rather extensively to clean out the lint.
@ DC_Cont: Appreciate you taking the time to post and include the info on your Bosch. I also have the Whirlpool WHD560CHW, and have been getting increasingly concerned about the lint that gets past the first filter, past the second filter (which in itself is a double filter), past the seal around the second filter, and past the hardware cloth between the second filter and the coils. I've read on here about this being a supposed Whirlpool design flaw, which I'm tempted to agree with, watching visible lint build up on the portion of the coil I can see through that little opening, which makes me dread the inevitable coil cleaning, and makes me wonder if I should have bought a different brand. Now I can stop wondering if I should have bought a Bosch, I would never buy an LG or Samsung due to lack of parts, so that leaves only the Meile or GE I have left to wonder about, and none other than the WP come in full size, so that was one of the deciding factors on the WP.
I clean BOTH filters after every load (even though WP says clean the lower one only every 5th load), clean around the lower filter opening, and once every 10th load stick a shop vac in the lower chamber to clean it up and attempt to pull a bit form the coils - can't really get close enough....
What is it with US heat pump dryers that the coils need maintenance? Haven't the Europeans used HP dryers for years? Have they solved this?
All that said, I'm pleased with the WP, because it is, as you note, "unremarkable" - I was concerned it would take much longer to dry clothes, but it does not. It also had the added benefit of clothes coming out much softer - I presume because it is not stiffening them with undue heat...
Lint seems to sneak past filters in pretty much ALL dryers, regardless of manufacturer. That's why cleaning lint out of dryer vents is supposed to be annual maintenance for everyone with a vented dryer -- even though most people don't bother to actual do it...
I'm surprised about the softer clothes, I haven't heard about that before. For me, "hard and crunchy" clothes usually means there is a problem with the water softener (we're on a well) that I didn't notice soon enough. Hard water has calcium in it, so the clothes get coated in rock, basically.
Bill