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Thread Number: 43520
Slower heating = lower consumption? |
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| Post# 639890 , Reply# 1 11/18/2012 at 07:06 (4,174 days old) by splittub (Europe) | ||
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Perhaps it requires more energy to heat up the water quickly *and maintain the heated temperature* for the duration of the wash, than to allow the water to reach the desired temperature *during* the wash. | ||
Post# 639895 , Reply# 2 11/18/2012 at 07:37 (4,174 days old) by logixx  (Germany) |
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Post# 639899 , Reply# 3 11/18/2012 at 08:08 (4,174 days old) by Launderess (Quiet Please, There´s a Lady on Stage) |
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One Assumed The Low/Gentle Heat Option
Merely disconnected or otherwise reduced the heating power for the dryer. However after reading various service manuals and such now believe low/gentle heat option simply lowers the temperature reached in the drum during cycle, but uses the same amount of electric power as things will take longer to dry.
I mean if one *bakes* laundry dry at a high heat setting it will be done sooner, but consume "X" amount of electric power. However if one goes to simmer or medium heat things take longer but the same amount moisture still must be removed so the same amount of heat is going to be used regardless. | ||
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Post# 639906 , Reply# 5 11/18/2012 at 08:35 (4,174 days old) by chestermikeuk (Rainhill *Home of the RailwayTrials* Merseyside,UK) |
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"so the same amount of heat is going to be used regardle | ||
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Post# 639918 , Reply# 6 11/18/2012 at 09:04 (4,174 days old) by DADoES (TX, U.S. of A.) |
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 One must consider this question from the P.O.V. of the power company. A higher input wattage = higher instantaneous demand on them. Demand costs extra. The cost is included/averaged in the rate even if they don't bill a residential account directly for it. As a somewhat extreme example, consider why power companies don't like electric tankless water heating. A full-size, whole-house unit can pull 28,000 watts or more. The power company has no way to know in advance when a consumer may suddenly "demand" that much instantaneous power, even if for only a couple minutes, so they must have enough reserve capacity on the system to feed it any moment. As compared to a traditional tank unit that may pull maximum of 4,500 to 5,600 watts. Even if it takes 20 to 30 minutes to heat a 50-gallon tank, that's much less instantaneous demand that the power company much purchase from the generating station. | ||
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Post# 639921 , Reply# 7 11/18/2012 at 09:17 (4,174 days old) by Launderess (Quiet Please, There´s a Lady on Stage) |
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Using A Miele Condenser Dryer
As an example we can see from the schematic that the *Heizung* (heat) circut that the dryer has two setting on it's thermostat, 58C and 73C. One assumes these are from switching the temperature dail between high and low but unless is reading the thing incorrectly(could be with such a bad copy) both legs of the heater are being fed regardless.
CLICK HERE TO GO TO Launderess's LINK | ||
| Post# 639922 , Reply# 8 11/18/2012 at 09:21 (4,174 days old) by mrb627 (Buford, GA) | ||
Fuel Consumption | ||
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Post# 639944 , Reply# 10 11/18/2012 at 10:37 (4,174 days old) by sudsmaster (SF Bay Area, California) |
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Theoretically, the amount of energy required to heat a body of water to a final temperature is the same regardless of the rate of heating.
However it's possible that a slower heating rate could result in a smoother temperature curve, especially when the final temp has been reached and is being maintained. Smoothing out the peaks could save a small amount of energy. A slower heating rate could also result in less heating of the non-water mass and surrounding air in the washer, resulting in further small savings. BTW, cars use more fuel per mile to travel at faster speeds due to wind resistance. An analogy to a dryer might be with air flow, but I don't think that heating rates have the same sort of effect. | ||
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Post# 640011 , Reply# 12 11/18/2012 at 15:15 (4,174 days old) by Tomturbomatic (Beltsville, MD) |
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Manys the time I have dried clothes in an outside dryer while it is raining. I am always amazed that even in the rain, the heat of the burner can increase the air's capacity to hold moisture sufficient to remove it from the tumbling load of laundry. | ||
| Post# 640066 , Reply# 13 11/18/2012 at 19:39 (4,173 days old) by arbilab (Ft Worth TX (Ridglea)) | ||
Fun question. Let's stick to heating wash water. Drying adds several other sets of variables.
In a lossless system--perfectly insulated--it always takes exactly the same kWh to heat the same amount of water from the same start temperature to the same operating temperature, no matter how fast or how slow you do it. In a lossy system--imperfectly or poorly insulated--the longer the water is above ambient the more heat is lost by radiation. In that case, faster is CHEAPER. But not by much, because the hotter it gets the greater the loss, so more time at full temp = greater loss. Industrial electric customers are billed by demand. Above is correct, that though demand isn't measured for domestic customers (in the US--Europe may differ) it's figured into the rate. Demand billing favors slower consumption. So even though the loss may be higher, the cost may be lower. At the rates Europe pays for electric, I can't for my life explain their obsession with boiling laundry. In 3 generations nobody in my family has washed above 140F and nobody has experienced a laundry-borne disease. I wash at 120F and I haven't had more than a 24-hour sniffle in 5 years. Oh, and I'm genetically European, specifically, UK. The only extraordinary step I take is, anytime I leave the house I do NOT touch my face with my hands, and wash them immediately when I get home. Wouldn't matter if I boiled clothes or went nekkid. Know what the most contaminated surface in everyday life is? The handle of a shopping cart. Can't boil those now, can we? | ||
| Post# 640133 , Reply# 14 11/19/2012 at 02:14 (4,173 days old) by MIKEKLONDON (London) | ||
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Try it out All I know is that if you use the low heat setting on a Miele it uses a low less power and only takes a few more minutes to dry the load + it does the job a lot better. Its all about the air flow. | ||
| Post# 640137 , Reply# 15 11/19/2012 at 02:43 (4,173 days old) by MIKEKLONDON (London) | ||
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Care labels Most care labels recommend low heat, in the uk one dot is low 2 dots high | ||
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Post# 640579 , Reply# 17 11/20/2012 at 23:19 (4,171 days old) by sudsmaster (SF Bay Area, California) |
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Shopping cart handles...
Yes, I could see those as being highly contaminated. However, I recently read that the highest bacteria count (E. coli) can be found on... drum roll... gas pump handles...
It makes me wonder what these people do inside their cars... In any case, I keep a small bottle of sanitizer gel in my car cup holder, and I TRY to wash my hands every time I return from a trip outside the home. Sometimes I forget and often I seem to come down with a cold as a result. Washing hands is great for controlling colds... but influenza virus is also spread by sneezing and coughing... I get a bit annoyed when I'm in a checkout line or on public transport and another customer is coughing or sneezing, esp if they don't bother even the gesture of covering their mouth and nose. Even worse when the checker is the one who's ill. I wonder how many other people he or she has infected that day. My last workplace was definitely not on the clean side. In addition to the mess created by the open machinery, my supervisor would spit on the shop floor, smoke, not cover his mouth when coughing, and not wash his hands after using the restroom. I'm so glad I'm out of there. | ||
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Post# 640582 , Reply# 18 11/20/2012 at 23:29 (4,171 days old) by sudsmaster (SF Bay Area, California) |
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It seems to me that boil washes date back to the days when fat based soaps were used, and high water temps really were needed both for maximum cleaning and rinsing. The high temps also help to remove stains from whites - just as high temps will fade most colors. I suppose that in the days when energy was cheap, boiling was cheaper than soap or those newfangled detergents. There's also something to be said for high temps killing most bacterial spores, but of course only even higher temps and pressure than are possible with home washers is really needed for sterilization (as I recall, it's 250F under 15 lbs pressure - something a home pressure cooker could do, in a pinch, if one needs to sterilize towels or knives for emergencies).
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Post# 640645 , Reply# 19 11/21/2012 at 11:24 (4,171 days old) by logixx (Germany) |
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As for washers saving energy: they simply heat less. Newer washers, as was found out by our consumer magazine, stop heating at 55C (Miele) or 45C (LG) even when a 60C wash was chosen. Or they will only heat the wash water once without reheating when it cools off. That's why I stay away from the regular Cotton cycle if I want a hot wash. It's the same with the infamous Normal cycle on US washers that doesn't seem to allow anything but warmish water.
Boil wash? Maybe once a year. | ||
| Post# 640659 , Reply# 20 11/21/2012 at 12:40 (4,171 days old) by Iheartmaytag (Wichita, Kansas) | ||
Remembering back to 9th grade physical science class. The same amount of work still has to be done, so the savings may be negligible, however, where the savings may occur is due to the longer tumbling time there will be a certain amount of evaporation due to the air movement through the load.
But total gain will be more or less a wash. (pun) because the longer tumble time, though may lead to evaporation, will also lead to cooling of the load of clothes, thus requiring more heating to keep constant. This does now equate to driving a car slower, the reason a car gets better mileage within a certain range of speed that at higher, or lower speeds is because of the wind resistance, and the overall efficiency of the engine. Though most engines reach maximum efficiency at full throttle or maximum capacity, this efficiency is negated by the wind resistance of the vehicle. But driving at a constant 50 MPH will achieve better mileage overall than driving 70 because the wind resistance is lower at 50 than at 70. | ||
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Post# 640752 , Reply# 21 11/21/2012 at 23:22 (4,170 days old) by sudsmaster (SF Bay Area, California) |
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I have measured the actual water temperature (using an infrared meter) of the wash water of the Miele 1918 vs. the 1065.
The 1065 heats to exactly the temperature selected. A 160F selection will heat to 160F in the 1065. However, the 1918 seems to heat to about five degrees F lower than the selection. A 160F setting will heat to about 155F in the 1918. I attribute this to the fact that it's a 1918A, which is supposedly the energy saving model. Its top temp is 170F (selected), vs the 190F of the 1918 model proper. Perhaps the 1918 model however also heats to about five degrees less than selected. | ||
| Post# 640756 , Reply# 22 11/22/2012 at 01:02 (4,170 days old) by arbilab (Ft Worth TX (Ridglea)) | ||
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| Post# 640863 , Reply# 23 11/22/2012 at 11:29 (4,170 days old) by turboace (Wilmington, NC) | ||
Changing a liquid to a gas will always require the same amount of energy all other conditions held constant, it is the laws of physics. When you dry clothes you need to change liquid (water) to water vapor (gas) that is exhausted in most cases, or condensed in others from the dryer. Energy is required to make this happen. The energy may come from the electric lines, gas lines, or the air surrounding the dryer. The idea that a lower heat setting will dry nearly as fast may hold true in some cases. The air entering your dryer from your home may have energy spent on it to condition it. In the summer, with your air cooling on, the air coming into the dryer will be dryer than the clothes, helping to hasten the drying process, but you have spent energy to pre-condition that intake air. In the winter when your heat is on, by raising the temperature of the air inside your home, you lower the relative humidity of the air compared to that of outside. This dryer air will help clothes dry faster, but again, you have spent energy to pre-condition the air. So, while it might seem like a load will dry almost as fast it still takes energy from somewhere to get that water to change into a gas and leave your clothes dry.
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