Are there any full sized (7-8 cu-ft) heat-pump dryers yet that are reasonally affordable? This is one energy sucking appliance I'd love to replace...
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Heat Pump Clothes Dryers
- Thread starter iPlug
- Start date
mspohr
Well-Known Member
They tend to be more expensive because of the heat pump mechanism. Regular dryers are simple with just a heating element or burner.
Nothing I have seen under $1k. Best I have kept my eye on is the Whirlpool Model #WHD560CHW. Current best price appears to be $1304.
It is rated at 7.4 cu. ft. capacity and CEF 5.2, which at Energy Star shows as the most efficient in this full size class (select clothes dryers then sort by CEF).
Product Finder — ENERGY STAR Certified Clothes Dryers
So let me get this straight.... these heat pump ventless clothes dryers are blowing air over the hot side condenser, blowing that over the clothes, then running the warm moist air over the cold evaporator, catching the condensate, then circulating the air around again, back to the hot side. Does it have a drain line so it can pump out the condensate? How much moisture is cycled into the environment around the appliance?
mspohr
Well-Known Member
Yes, the air recirculates from hot through the clothes to cold. Condensate is pumped to the same drain as the washer uses. No vent for air. The dryer is warm to the touch. So All of the electricity energy 800W it uses seeps into the house. Fine for winter. Summer we use a clothes line.
You need a heat pump water heater to take that heat and put it into hot water. LOL
This appears to be due to a somewhat arbitrary testing criteria cutoff which forces what we would consider to be compact dryers to dry almost 3x the amount of laundry.
Energy Star uses 4.4 cu. ft. capacity as the cutoff with < considered "compact" and > considered "standard". For the purposes of Energy Star calculating CEF, they use a test load size for standard dryers of 8.45 lbs and 3 lbs for compact dryers. When sorting dryers by CEF, the top 5 currently have capacities of 4.5-4.9 cu. ft. so just barely get classified as standard size and are listed as having ~2x the annual estimated kWh usage as the next lowest CEF units which have capacities of 4.0-4.1 cu. ft..
My strong suspicion is that if they tested the top 5 highest CEF units with the same "compact" 3 lb test loads, they would have lower annual estimated kWh usage than the 4.0-4.1 cu. ft. units.
Clothes Dryers Key Product Criteria
SageBrush
REJECT Fascism
Ahh, gotcha ... I think.
8.45/3 = 2.8x
CEF is Kg (laundry) per kWh electricity for heat pumps
It is interesting that a large drum that is under 2x the volume of the small drum is handling almost 3x the laundry weight.
If a typical small unit consumes S kWh,
then a large until would consume 2.8*S kWh if it had the same CEF, or 1.4*S kWh with a CEF twice as high.
Yet the stickers expect 2*S consumption in the larger units.
Have you figured out this discrepancy ?
The numbers all check out on my end.
For example, compare:
- Whirlpool - WHD560CH**, drum capacity 7.4 cu-ft, CEF 5.2, 460 kWh/yr estimated use
- Insignia - NS-FDRE44W1, drum capacity 4.5 cu-ft, CEF 10.14, 236 kWh/yr estimated use
(CEF 10.14/ CEF 5.2) * 236 kwh/yr = 460 kWh/yr for the 7.4 cu-ft Whirlpool unit
Let's also verify using mspohr’s 4.0 cu-ft drum capacity Samsung DV22N6800HW/A2 since it is classified as compact. This has CEF 5.85, 145 kWh/yr estimated use.
Now we need to use the ratio you noted: 8.45 lbs (standard)/3 lbs (compact) = 2.82
Let’s compare it to the Whirlpool above:
(CEF 5.85/ CEF 5.2) * 145 kwh/yr * 2.82 = 460 kWh/yr for the 7.4 cu-ft Whirlpool unit
So CEF is the only true measure of efficiency here. The Energy Star estimated usage, while true to their formula, guesses wildly that anyone who has a >4.4 cu-ft drum capacity unit will magically dry 2.82x as much laundry annually than a person buying any <4.4 cu-ft capacity drum unit. Certainly a person buying a "standard" unit is very likely to do more annual drying than a person buying a "compact" unit. But their guess-o-binary-ratio should scale better, perhaps by each tenth of drum cu-ft.
SageBrush
REJECT Fascism
As you say, the CEF is a measure of efficiency. The higher the CEF, the less energy used for the same amount of laundry.
If these two dryers are drying the same amount of laundry then the expression would be
Whirlpool annual kWh = 236 / (CEF 5.2/CEF 10.14)
The result is the same as you wrote, it just makes more sense to me. I'll track down some examples of where the numbers has me confused. In the meantime -- why would one dryer be 2x as efficient as another ?
Yeah, that is why I want the CEF to make sense, so I can just use that number and ignore the annual kWh consumption.
SageBrush
REJECT Fascism
Now the arithmetic is making sense. <<shrug>>
Thanks @iPlug for the 'binary' hint
I'm still wondering why some machines have a CEF in the 9 - 10 range while most are in the 4 - 6 range. My guess for now is it depends on how quickly the manufacturer sets the heat pump to operate. If correct then the trade-off is about 20 - 30 minutes more time per load to use about 30% less electricity. I think I'll look for a machine that lets me choose.
What CEF will EnergyStar rate these machines that let the operator decide on the drying speed ?
Thanks @iPlug for the 'binary' hint
I'm still wondering why some machines have a CEF in the 9 - 10 range while most are in the 4 - 6 range. My guess for now is it depends on how quickly the manufacturer sets the heat pump to operate. If correct then the trade-off is about 20 - 30 minutes more time per load to use about 30% less electricity. I think I'll look for a machine that lets me choose.
What CEF will EnergyStar rate these machines that let the operator decide on the drying speed ?
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Was searching the Miele website to try to get some clarity on this, since EnergyStar lists them as having a best 9.75 CEF unit with next lowest model dropping down to 6.37. Could find nothing to suggest the delta in CEF was a more advanced heat pump. So yeah, maybe this has to do with testing cycle parameters you mention.
SageBrush
REJECT Fascism
I'm tempted to call these heat pumps 'dehumidifiers.'
Some of them expect a drain for the condensate; others have a storage container that has to be manually emptied every load or two. It is hard to escape the impression that these machines are very sensitive to lint since the manufacturers politely but quite insistently remind the owner to clean them every use. I'm willing to wager that some (perhaps most) of the poor reliability ratings some of these machines get is related to poor maintenance by US consumers used to vented machines that are much more tolerant of benign neglect.
So on paper, a full (American) size heat pump clothes dryer with high CEF is finally here:
LG - WKHC202H*A
Drum Capacity (cu-ft): 7.2
Combined Energy Factor (CEF): 8.0
Estimated Annual Energy Use (kWh/yr): 299
Reported Date Available on Market: 3/31/2022
Product Finder — ENERGY STAR Certified Clothes Dryers
Only problem is Mr. Google can't seem to find this guy for sale anywhere.
LG - WKHC202H*A
Drum Capacity (cu-ft): 7.2
Combined Energy Factor (CEF): 8.0
Estimated Annual Energy Use (kWh/yr): 299
Reported Date Available on Market: 3/31/2022
Product Finder — ENERGY STAR Certified Clothes Dryers
Only problem is Mr. Google can't seem to find this guy for sale anywhere.
SageBrush
REJECT Fascism
Looks like finally some limited availability, though as best I can see is currently only sold with a paired washing machine unit:
LG WKHC202HBA $3,099.00
https://www.abt.com/LG-27-Black-Ste...eat-Pump-Dryer-Combo-WKHC202HBA/p/186221.html
LG WKHC202HBA 27 Inch Smart Electric Washtower™ with 4.5 Cu. Ft. Washer Capacity, 7.2 Cu. Ft. Dryer Capacity, TurboWash™ 360 Technology, Steam Technology, ThinQ™ Technology, Advanced AI DD™ Washing, Smart Pairing™, Allergiene™ Wash Cycle, Sensor Dry, Tempered Glass Door, and ENERGY STAR® Certified
