Using an electric clothes dryer off-grid



  • Volvo FarmerVolvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
    Re: Using an electric clothes dryer off-grid

    This is likely my last post on the subject. I have been repairing appliances for twenty three years. I have had Maytag, Frigidaire, Asko, GE and Whirlpool dryers in my home, in both gas and electric. My opinion is that the Whirlpool dryer with the lint screen on the top is the best design on the US market for drying clothes quickly and efficiently. It is a robust, well engineered unit whose major design points haven't changed in forty years. You might look at it and say it can't work well because the heat and exhaust both come in the back, yet somehow it does.

    I am also not of the consensus that there is much room for efficiency improvement in electric clothes dryers. Dryers need lots of heat and lots of airflow to drive the moisture out of the clothes. Washers, refrigerators, and dishwashers have become much more efficient in the last 40 years. Why are dryers still using 4500 watt heating elements and 1/3 hp motors? Because manufacturers are lazy and consumers won't buy one? I think not. It takes heat and airflow to dry clothes quickly and there is no way around that fact.

    I agree with Chris' observation that theoretically, a dryer could be designed with a heat pump to run more efficiently than with a resistive element. So we need a heat pump that can produce 15000 btus to equal a 4500 watt element. The compressor itself would run over $200 plus the costs of the evaporator and condenser coils, not to mention controls and refrigerant. All this to replace a $20 resistive element and $5 bimetal thermostat, and it still has to fit in a 30"x30"x36" box to fit in people's laundry rooms. Manufacturers aren't stupid. I would imagine they could build such a thing for $1500. It would save $40/year over the cost of a traditional dryer that costs $400 and the payback would be on the order of 25 years. There is a darn good reason that the heat pump hasn't been widely implemented for clothes drying. It doesn't make sense economically. It also doesn't make sense "green" as the embodied energy in a heat pump system is an order of magnitude larger than a resistive element and the complexity increases repair costs over time.

    Dryer technology hasn't changed much in forty years for a reason. Electronics are all the rage now and if you can accurately shut the thing down when the clothes are dry instead of letting the timer run out, I suppose there's some savings to be had there, but it's nothing that frugal housewives haven't known all along and adjusted the time on the cycle to the size of their loads.

    Buy a cross vented dryer if you want, but I have watched the things work, I have felt the airflow out the back after 15 minutes of towels with a full lint screen versus the Whirlpool with a half full screen and I have watched the Whirlpool dry faster time and time again. I have a 15 year old Whirlpool in my own house, and I could have replaced with countless other brands over the years. Sorry if I'm a little opinionated on the subject, but I eat breathe and sh#t home appliances and get a little passionate about the subject.
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Using an electric clothes dryer off-grid

    "Dryer technology hasn't changed much in forty years for a reason. Electronics are all the rage now and if you can accurately shut the thing down when the clothes are dry instead of letting the timer run out, I suppose there's some savings to be had there, but it's nothing that frugal housewives haven't known all along and adjusted the time on the cycle to the size of their loads."

    now that would work well for me as my other half being a total idiot on appliances runs the electric dryer max time no matter what she puts into it. and to think my wife calls other people stupid. shudder.:cry:
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Using an electric clothes dryer off-grid

    I'll guess you've never worked in manufacturing. I have. Trust me; they are lazy and will not make any design change unless it improves the profit margin. So long as it works and sells, that's all that is necessary.
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Using an electric clothes dryer off-grid

    The information presented here by everybody is good. I learned more about clothes dryers than I even wanted to know ;)

    My experiment with running the dryer's element on 120 volt, for us, I think will work OK. We're just a household of two so we don't have a lot of laundry that would make it necessary to dry clothes real fast. I'm satisfied that it does the same job on less energy input, even with the heavy hard to dry stuff like a load of denim jeans or towels.

    Maybe after awhile we'll find something that makes it less desirable than using the Big Heat. But after doing three loads with it on 120 volt now, I don't think so. Not everybody likes to dry clothes on a line in the house in the winter. We used to do that and it got old after awhile, and that's why we bought the dryer. But it's always been a challenge to find the power to run it. Wired 120 volt, a person could run an electric clothes dryer with even an Outback 3524 with no problem (at least our dryer you could). And for off-grid use the electric dryer gives you the option of using your RE power instead of burning gas. And you can also use the generator to do it with plenty of power left over to charge batteries at the same time with even a small 3 kW generator.

    So in the end I'm glad I tried it.
  • westbranchwestbranch Solar Expert Posts: 5,114 ✭✭✭✭
    Re: Using an electric clothes dryer off-grid

    Sorry for picking out the lint, but no one mentioned Bosch, a brand of washer & drier my wife (SWMBO) LOVES...

    the dryer goes in fits and stars by rotating the drum one way then the other, an irritating side to it is it squeaks differently depending on direction...BUT SWMBO claims it dries ALL loads faster. It has a batch of electronics that control it so it shuts off when the goods are dry.
    The only time I have noted things are a bit damp is wen the dreaded sheet tangle occurs. (I am the designated dryer emptier)

    Sorry I am not able to test the draw of the drier or the washer, it uses a standard drier wall plug for the 240 connection and the matching 110 washer, a whiner at 1800rpm, uses a Euro plug. from the back of the drier , for power.

    other wise a great thread.
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  • solarvicsolarvic Solar Expert Posts: 1,050 ✭✭✭
    Re: Using an electric clothes dryer off-grid

    The bosch dishwasher my daughter works well also. It has a little red light that shines on the floor so you can tell that it is operating. Never saw a quieter one. solarvic
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Using an electric clothes dryer off-grid

    Sort of an update for folks wondering how this low-voltage dryer works. My wife has done many loads of laundry with it without a single problem. She already has the adjusted drying times figured out. According to her she is getting LESS lint in the screen at the lower temp and longer tumble times than she got before at Raging Inferno with a shorter tumble time.

    So evidently heat is also a cause of lint from clothes drying. The only thing it won't dry in one shot because of the 70 minute limitation on the timer is a big load of bath towels. It usually requires an additional 30-40 minutes for towels. Otherwise it has worked fine.
  • lukegreenlukegreen Registered Users, Users Awaiting Email Confirmation Posts: 1
    ChrisOlson   Can you draw a diagram so I can understand what you mean by . I simply pulled that leg off and ran a neutral wire instead so the element now runs on 120 volt instead of 240. This cuts the element's power draw to 1,200 watts.I ned some help anyone able to show me this please.
  • BB.BB. Super Moderators, Administrators Posts: 28,186 admin
    Chris is not a member here anymore. And i do not know anyway of contacting him.

    Do you have a schematic for your drier?

    Many times, the drier motor and timer+electronics run from 120 vac, and only the heating element runs from 240 vac. Schematics should help.

    Do you have a large solar power system? Or could you run a propane fueled drier?

    Off grid power tends to be pretty expensive.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • oil pan 4oil pan 4 Solar Expert Posts: 759 ✭✭✭✭
    edited February 28 #41
    I observed the same thing.
    So I rewired my dryer to a heavy duty 3 way switch. In the on or up position the heater element runs full 240v power for denim or other heavy clothes and the off position develops 120v across the heating element, for pretty much everything else.

    It's pretty basic, most electric heating element dryers are set up almost identical, unless you have a real fancy one.
    One leg of 120v power runs your motor, timer, and heating element, the other leg of 120 just provides full 240v potential across the heating element, all you have to do is remove line power from the heating element only side and connect it to neutral.

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