Thread Number: 70553
/ Tag: Modern Dryers
Dryers and how they work |
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Post# 934909 , Reply# 2   4/27/2017 at 08:08 (2,548 days old) by Yogitunes (New Jersey)   |   | |
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there were a select few dryers that offered 'modulating' heat temps.....in that meaning, like your gas stove, the temp could be selected by the turn of the dial, from a low simmer to a boiling high......
todays dryers mostly operate at HIGH temp all the time..... by selecting a temp like "Low", doesn't offer that the max temp not go over 120 degrees, actually that's the minimum before the heat source comes back on.... lower temps are achieved by allowing a longer cycled 'heat off' time before it activates again.... this has always puzzled me of people who wash in cold water, for the reason of preventing shrinkage.....yet toss those items into a 160/180 degree dryer....way hotter than the temp of the water heater if they washed these same garments in hot water.... if anything, place a thermometer in the vent line, and by selecting temps, see how hot the air temps gets, and how low it gets before the heat comes back on, and how long of a time between the two.... there is of course the 'soft heat' feature of a Kenmore dryer....in that every time the heat cycles on, the temp is dropped/cut off by 5 degrees....basically as the clothes gets drier, the temp lowers down...if you ask me, the best system ever...other dryers operate at high temps across the whole cycle, until 'cool down' take place.... |
Post# 934913 , Reply# 4   4/27/2017 at 09:38 (2,548 days old) by johnb300m (Chicago)   |   | |
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Post# 934914 , Reply# 5   4/27/2017 at 09:49 (2,548 days old) by panthera (Rocky Mountains)   |   | |
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Which use water or air to provide the cooler side of the temperature gradient raise the temperature in the drum as high as possible to increase the effectiveness of the condensation process.
I, too, am puzzled by people who only wash in cold water in order to 'save their clothing' then use a tumble dryer or a heated iron to press their clothes.
They're not thinking rationally.
Of course, it's still best to wash clothes in the warmest water they can take. Ideally, the temperature of the water should be held at the most effective point for the various enzymes in use for a long enough period of time for them to do their work.
Sadly, cold water just isn't warm enough for enzymes to do a very good job. That's why detergents and dryer sheets and fabric softeners use stronger and stronger perfumes - to cover the filthy mess distributed over the clothes after they've been 'cleaned' in ice-cold water.
Unless the clothes are being damaged, I'd not worry about the dryer running too warm. This is the temperature range my Miele water-condensing dryer and my AEG air-condensing dryer used for all settings except special treatment (which took forever).
To my horror, the US government, back when they actually did consumer saftey, showed temperatures at the exhaust vent of the dryer of over 204C when the vent pipe was blocked before the internal safety thermostats turned the heat off. That's way above the auto-ignition point for dryer lint! Yikes! Time to recheck our dryer vents! |
Post# 934920 , Reply# 6   4/27/2017 at 10:55 (2,548 days old) by Kb0nes (Burnsville, MN)   |   | |
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I've posted this before but it might be decent information in this thread too
This is a profile of the air temp of my gas Cabrio dryer and a load of towels. Thermocouple was in the airstream on the lint screen. Temps are degrees F |
Post# 934945 , Reply# 7   4/27/2017 at 14:55 (2,548 days old) by Launderess (Quiet Please, There´s a Lady on Stage)   |   | |
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One reason why early tumble dryers ran very hot as did laudromat machines was the rather pitiful extraction of early washing machines.
For American homes top loaders and even wringer washers dominated the domestic market. None aside from a few machines like those offered by Frigidaire had very high spin speeds, and wringers equal at best about 200rpms. Either way you are putting basically sopping wet laundry into a dryer. You're going to need that high heat to "bake" out all that moisture. In laundromats extraction from front loaders wasn't that much better, and top loading were what they were. Either way a place could "make money" on the dryers even if they ran hot (which many did), because customers tend to over dry. Some laundromats did offer separate Bock extractors to "cut down drying time", especially for heavier things. On the commercial side of laundry it has long been recognized that the most efficient and effective way to remove moisture from the wash is via extraction. That is finally catching on with domestic machines as washers are able to offer faster final spin speeds. That in turn means less need for energy from dryers. When using laundromat dryers always start off on "High" but will keep an eye on how load is progressing. Once things reach a certain stage of dryness will move the temp down to "Med" or even "Low". The last five minutes are always on "Delicates". Find the results are better than allowing laundry to bake dry, especially since the cool down period on these dryers is only one or two minutes. Not nearly long enough to reduce temps and prevent hard creases. |
Post# 935297 , Reply# 8   4/29/2017 at 11:55 (2,546 days old) by Tomturbomatic (Beltsville, MD)   |   | |
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Phil, I am surprised at the 40 degree swing, fast as it is, with a thermister during the drying. I am spoiled by the steady drying temperatures of my gas dryer with the modulating burner that holds a steady 165F until cooldown. |
Post# 935778 , Reply# 11   5/2/2017 at 02:14 (2,544 days old) by logixx (Germany)   |   | |
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Post# 936320 , Reply# 12   5/4/2017 at 16:26 (2,541 days old) by kb0nes (Burnsville, MN)   |   | |
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Tom, It would be interesting to do a thermal profile on a machine with a modulating burner. Of course it wouldn't oscillate like mine did. I bet there is a fair bit of variation there too.
Does anyone make a dryer with a modulated burner any longer? It is an interesting technique but the cost of the gas valve may have more then offset any possible advantage they could have had. |