Heat Pump Dryers

[Dockhead]

Originally Posted by a64pilot

How about this, the other end of a heat pump is of course the cold end.
Your clothes drier could also be your freezer . . . .

Well, but you need both ends for this use. You blow air from the hot side into the drum, then run the warm wet air over the cold side (the evaporator) to condense the water out of it. Then this same cool dry air is run back through the hot side (the condensor) before going back to the drum. It's ingenious. It's not actually a heat pump -- it's a water vapor pump. Because the air is chilled before it goes to the hot side, it isn't even really hot in the drum -- just bone dry.

[a64pilot]

Originally Posted by Dockhead

Well, but you need both ends for this use. You blow air from the hot side into the drum, then run the warm wet air over the cold side (the evaporator) to condense the water out of it. Then this same cool dry air is run back through the hot side (the condensor) before going back to the drum. It's ingenious. It's not actually a heat pump -- it's a water vapor pump. Because the air is chilled before it goes to the hot side, it isn't even really hot in the drum -- just bone dry.

Yes, I figured it out. It’s sort of a dehumidifier with clothes in the way of course. A dehumidifier flows air first over the evaporator, then over the condenser.
Pretty slick, but 850 Watts is still a lot of power for most of us.
We do the tropics thing and just use the lifelines and look like the Beverly Hillbillies for half a day once a week or so.

[hellosailor]

Ages ago I either saw or read something about life above the Arctic Circle, and they mentioned that people hung their laundry outdoors--and literally let the winds freeze-dry it. So the concept of dehumidifying your laundry with cold instead of heat has been around, even if it hasn't been in machines.

It SOUNDS real nice, but I have to ask what's the price of one? And, since it is another refrigeration system at heart...doesn't this mean another mechanical system that's going to be far less reliable than a simple flame or wire heat source? In the long run?

[Dockhead]

Originally Posted by hellosailor

. . . It SOUNDS real nice, but I have to ask what's the price of one? And, since it is another refrigeration system at heart...doesn't this mean another mechanical system that's going to be far less reliable than a simple flame or wire heat source? In the long run?

They are fairly costly -- maybe double the cost of a condensor dryer. I paid something like €900 for mine. But with the high cost of producing electrical power on board a cruising boat, this would pay for itself pretty fast. The difference in power consumption is huge:

https://www.youtube.com/watch?v=Nh-j0sWBEJA

This guy got average power consumption of a conventional dryer at 2300 watts (just like mine on my boat) and for the heat pump dryer -- 550 watts. About triple the kW/h needed with the normal dryer for a load.


Like all of us, I did the Beverly Hillbilly lifelines routine for decades. It works OK in sunny climes. But where I sail, there may be long periods of damp, cold weather where nothing will dry on the lifelines. I have found cruising these last 10 years with a dryer on board to be the best thing since sliced bread -- the dryer is far more valuable than the washer (although I love that too). In wet weather, you can always wash clothes in a bucket, but you can't dry them that way.


Some people just don't care -- they go into camping mode and don't mind wearing dirty clothes for a while between laundries and some don't even bathe all that often. That's a matter of personal taste, but that is not for me. I bathe once or twice a day, even on passage, and I have to have clean clothes at all times, or I feel crappy, and I don't go sailing to feel crappy. YMMV.


In Greenland, we had strictly limited fresh water supplies because our watermaker didn't arrive in time, and my crew said -- no problem, and just stopped bathing. Not me! I was on the swim platform every day with a bucket of icy sea water, sometimes with chunks of ice in it, scrubbing my bod and washing my hair. One half liter of nice warm fresh water for the final rinse.

[Kenomac]

High cost of electric power? Our 450W of solar keeps things topped up every day. I’m doing a load of laundry and making coffee as I write this.... and haven’t yet run the generator over the past three weeks.

[Pizzazz]

May be we are overthinking this. In hot climates, nothing beats the sun. In cold climate, the air is usually very dry to begin with. It is so much easier to use a forced air diesel heater to produce the required heat. You hang the clothes in the head and max the heater for an hour or so.

[a64pilot]

Originally Posted by Kenomac

High cost of electric power? Our 450W of solar keeps things topped up every day. I’m doing a load of laundry and making coffee as I write this.... and haven’t yet run the generator over the past three weeks.

Yeah, try running a drier, it’s not going to work long
I’m amazed you can get by with so little Solar, good that you can, but I’m surprised.

[a64pilot]

Originally Posted by Pizzazz

May be we are overthinking this. In hot climates, nothing beats the sun. In cold climate, the air is usually very dry to begin with. It is so much easier to use a forced air diesel heater to produce the required heat. You hang the clothes in the head and max the heater for an hour or so.

Northern climes though, especially in fall and spring, assuming your not there in Winter, there can be long stretches of to me cold dreary misty rain.
I loved Germany in Summer, but when that cold misty rain and heavy overcast skies kicked in after Summer I hated it.
Not that it ever rains in England etc.

[senormechanico]

I'd love one of those dryers, but the boat's too small. We get by with as much black things as possible.
Black towels, especially. In the PNW, they dry quickly in even semi-cloudy conditions.

[Kenomac]

Originally Posted by a64pilot

Yeah, try running a drier, it’s not going to work long
I’m amazed you can get by with so little Solar, good that you can, but I’m surprised.

Five panels + five controllers = no shading issues & high efficiency.

[hellosailor]

The guy in the video was also talking about a run time of 1h 15m, which is nearly triple the 30 minutes that a conventional drier might have taken. Even if it was only double what a conventional drier needed, that changes the energy savings to more like 1/3--but doubles the time that you need to attend to the dryer, or wait around for it.

Interesting concept though. A net energy savings is still good. Is yours as big as that one, or do they make smaller sizes?

[dannc]

The other issue is reliability. How long will the water pump and heat pump last? What will it cost to repair?

Our clothes dryer in the house is about 20 years old. I have had to replace the heating element twice which is pretty easy and cheap to do.

Some quick reads on reviews of a couple of the heat pump dryers state that the driers have two lint filters. One is easy to change as a vented drier but the other filter requires a service call. The second filter is not easy to access.

Later,
Dan

[Dockhead]

Originally Posted by hellosailor

The guy in the video was also talking about a run time of 1h 15m, which is nearly triple the 30 minutes that a conventional drier might have taken. Even if it was only double what a conventional drier needed, that changes the energy savings to more like 1/3--but doubles the time that you need to attend to the dryer, or wait around for it.

Interesting concept though. A net energy savings is still good. Is yours as big as that one, or do they make smaller sizes?

Well, no -- he was measuring kW/h for the whole cycle:




I can't vouch for the accuracy of the test or the comparability of machines, but sounds right to me.



Mine is a normal standard dryer. I haven't seen small ones and I doubt they exist. I suppose it would be difficult to pack all that gear -- compressor, condensor, evaporator -- into a small package.

[hellosailor]

Dockhead-
Ah, kw HOURS. Didn't realize that. Still seems like magic. Wasn't it GE who was making noise a couple of years ago that they would use ultrasonic energy to dry clothes without heat? I wonder if that flopped.

Dan-
My friends next-door neighbor is a retired appliance repair man. If you've gotten 20 years out of any new appliance, that's apparently twice the expected average these days. His experience was that the computers and electronic controls are what continue to fail, and from what I've seen that's a big issue. Like, "the board" replaced twice in 8? years in a dishwasher, once in ten years in a GE electric stovetop and oven, then the oven was replaced because a second board would have cost $400 versus $600 for a whole new oven.
Samsung's engineering also doesn't impress me. (Which is not necessarily unique to them.) My tablet blew apart from a swollen battery. It took about 6-7 weeks before the long saga of replacement got done, with multiple oopses from their end. Same as the Galaxy7 phone issues, I expect. Longevity just doesn't seem to be one of their concerns.

But then again...surely a washer or drier on a boat has to be in light duty service, as compared to one in a house with two kids running six? loads of laundry every week?

[a64pilot]

Originally Posted by Dockhead

Mine is a normal standard dryer. I haven't seen small ones and I doubt they exist. I suppose it would be difficult to pack all that gear -- compressor, condensor, evaporator -- into a small package.

I believe it can be done and not all that hard either, question is, is there enough a market to make it profitable?
Look at how small $99 countertop ice makers are, and they make a profit selling at $99 That is the part I can’t figure out, with shipping from China and all.