Timed Dry Cycle

[Chetlaham]

Why do some dryers only offer 50 minutes of timed dry while others offer 70, 80 and still others 90 minutes? How do manufacturers choose what maximum dry time to put on their dials?

 

 

I ask because I came across this dry guide from a Kenmore owner's manual:

 

 

 

I notice Towels, Jeans and bedspread dry times are based on a heat setting of high. Does that mean the user should not dry them on medium or delicate? I only use medium heat for towels because I find high to be way to hot. And since the manual recommends resting the time as needed, does that mean its common for clothes to come out of the dryer damp?   

 

 

 

https://s3.amazonaws.com/sm-backend-production-attachments/owners-manual-3405586-RevA.pdf

 

[qsd-dan]

"How do manufacturers choose what maximum dry time to put on their dials?"

I've noticed that lower end dryers usually have a longer timed dry cycle due to more space on the timer dial from lack of options. Just an observation of mine. Usually most people aren't using a timed dry cycle with an auto dry option, especially a sensor auto dry model. Actually, I should rephrase that. The manufacture probably ASSUMES the owner won't use the time dry cycle much. I know a few people who spend big money on a TOL model and use timed dry only 100% of the time.

"I notice Towels, Jeans and bedspread dry times are based on a heat setting of high. Does that mean the user should not dry them on medium or delicate?"

It should be fine, it just takes longer to dry. Delicate would probably take forever on a bedspread and well beyond the maximum allowable time for the timed dry cycle. The cooler heat settings may or may not affect the accuracy of the auto dry cycle. In my experience, some dryers it does, others it doesn't.

"I only use medium heat for towels because I find high to be way to hot."

Should be able to use the combo of "medium" heat along with "more dry" to get the desired results. Gotta play around with it.

 

[maytag85]

Oddly enough, my Maytag DE806 franken dryer only has a low heat setting, things surprisingly dry fairly quickly despite the temperatures only being 120F. I use timed drying for small loads or bed spreads that won’t dry on the auto dry cycle since it’s only cycling on the high limit thermostat, everything else specifically gets dried on the auto dry cycle.

 

[Chetlaham]

<blockquote>
<span style="color: #ff9900;">I know a few people who spend big money on a TOL model and use timed dry only 100% of the time. </span>

 

 

 

</blockquote>
Now you've got me intrigued. Do you know their reasoning behind doing this?

 

 

 

[DADoES]

 
- Ignorance and fear as to what "auto-dry" means, how it functions.

- Desire to know exactly how long the dryer will run for the load being ready in XX minutes or at X:XX o'clock.

- Mix of heavy and light items in washloads which throws accuracy of auto-dry askew for heavy items ending a bit damp.

- Habit.

 

[DADoES]

 
I recently redid the exhaust on mom's neighbor's dryer.  It's a corner of their laundry room, with the exhaust port on the right-side exterior wall.  They had enough flex duct piled behind the dryer that'd it probably extend 6 to 8 feet.  I discovered the situation when helping them get a belt-and-idler-and-rollers replacement situation into order.  I went back and changed it to a 90° elbow on the dryer with a short length of duct straight to the wall.

A load was finishing in their TR5.  She put it in the dryer and set it to Timed.  A WP model with mechanical timer and moisture-sensing (not thermostatic).  I advised that the exhaust reconfigure will cut at least 10 mins off the drying time, possibly 20 mins.  Why not use the auto-dry cycle which will automatically adjust the time?  She was befuddled on the auto-dry so I explained how it works and that a bit of experimentation may be needed to find the sweet-spot that works best for her load conditions.  I don't know if she'll continue to use it ... I'm guessing probably not.

She did tell me later that drying takes ~20 mins less after the exhaust reconfiguration.

 

[maytag85]

All auto dry does is run the timer when the heater or burner cycles off, turns it back off when the heater or burner cycles back on. This will continue until it’s overriden towards the cool down to off. Essentially a delayed sort of timed cycle that runs the timer when necessary, shuts off when necessary.

A moisture sensor may be accurate in some scenarios, but I find a thermostat to be more accurate since moisture sensors can be real screwy at times. A thermostat simply goes by air temperature, the exhaust temperature will be cooler when items are still damp, will heat up when things begin to get more dry.

Here’s one thing that’s for sure, don’t really need auto dry when you have a Whirlpool built gas dryer with the 37,000 btu burner. Have a friend who recently put a ‘57 Kenmore gas dryer into service with the 37,000 btu burner, things take at most 30 minutes to dry to completion.

 

[Chetlaham]

Sean, do you have a wiring diagram to the DE806? You say you converted it to low heat only? The dryer should not be cycling on its high limit, thats to hot and not safe. 

 

 

I agree that mixed items can trick auto dry- the exhaust temp goes up but bulky items are still wet.

 

37,000 BTUs is about 10,800 watts of 45 amps at 240 volts. Thats double the wattage of an electric dryer. Sure would speed things up. Older dryers were offered with a 50 amp plug and circuit but never caught on. I wonder how those dried.

 

[maytag85]

Reply #7

The high limit thermostat on the ‘66 to ‘75 Maytag HOH’s was only 155F, have a 160F thermostat installed since 150F to 155F is a bit too sensitive, 160F is sensitive but nowhere near as sensitive to a 150F to 155F thermostat. It’s still sensitive, but not as sensitive as if it were to have a thermostat rated 5F to 10F cooler.

Some people may beg to differ about the Maytag HOH design, but since they only have a 4500 watt heating element, there’s a lot less amperage flowing through the thermostats and timer contacts, certainly a lot easier on thermostats.

I should clarify, my Maytag DE806 isn’t a real DE806, it’s nothing more than a DE407 with the console light wired in place of the neon indicator light above the timer.

 

[Chetlaham]

Ok, now I see why the auto dry won't advance. The cycling stat must open first in order to send power back up to the timer. These design did not use a resistor, instead a 3 pole cycling stat. It might not hurt anything to go back to the original hi-limit rating and rely on the cycling stat. The manufacturers have already done the calcs so if you aren't exceeding the OEM high limit and the OEM cycling stat you should be good.

 

[maytag85]

Reply #9

The 160F thermostat I have installed for the high limit is as close as you can get to the original OEM part which was L155-30, the thermostat I have installed is rated for L160-20 which is close. There are a few L155-30 thermostats out there, but have to improvise, 160-20 is close to the stock thermostat.

I did experiment with a L140-10 and L150-20 thermostats, resulted in long, long drying times, auto dry didn’t work as intended since it would be the same dryness regardless since the clothes were dry before the main cycling thermostat was satisfied, cycling only on the high limit. Was fairly quick with the L180-40 thermostat, but the front of the cabinet got too warm for my liking and certainly will shorten the life of the felt seal which prevents items from falling on the heating element and shorting it out.

 

[Chetlaham]

I see your issue and now understand why you wanted to go with a dropper resistor. Maytag never wired the high-limit into the timer. Whirlpool used a 3 pole high limit, 3 pole delicate and a 3 pole normal stat like below: 

 

 

 

 

That way if any stat tripped for any reason, the timer would advance. IMO not very smart for Maytag to no include the high limit since a clogged vent of failed cycling stat would result in the dryer never shutting off. 

 

 

Do you still want the resistive dropper circuit or do you just want to stick to time dry?

 

[maytag85]

Reply #11

Just going to leave it as is at the moment since it’s not broke. With the power dropping resistor, the timer motor would get power regardless of wether the heat was on or off. The resistor was stepping down the voltage since if I advanced the timer manually to the cool down, the timer motor would speed up. Was sort of working, but not working as intended. Since I transferred the glass lense from the 808 console to the 806 dryer console, putting that idea to rest.

Though, I’ll probably need to power dropping resistor for something else since I am going to be transporting a Whirlpool Mark 18 console onto my ‘63 Whirlpool Imperial dryer (also going to transfer a console onto the ‘63 Whirlpool Mark XII washer), will just be a thermostatic auto dry and not a pesky moisture sensor.

 

[Chetlaham]

Sounds like it was not hooked up right, a contact/jumper was not taken into account within the timer, or you've got a loose connection. With stats closed and the heater running the voltage drop across the circuit should at absolute most be one or two volts. I can't picture 2 volts being able to drive the timer motor.   

 

[Chetlaham]

Sean, if you're willing to trade in timed dry for a super auto dry you can go the following route. As long as the heater contact is a drop off on break (positive shut-off) at the end of the cycle (which most likely it is) and you remember to set the timer with with both the heater and motor contacts engaged at the start of any auto dry cycle- following concept will work flawlessly. You will also retain your cool downs and your air fluff cycle. 

 

 

The long auto dry cycle has the advantage in that it will compensate for your reduced cycling temperature and take big bulky loads into account both that would otherwise trick the dryer into shutting off early. I've noticed that a lot of dryers, like my previous late 90s GE for example, would always shut off with the clothes still damp when set on auto dry + low heat. Further the timer will run regardless of which thermostat tripped out. An important safety feature.  

 

 

To get this to work you'll have to move one lead of the timer to the yellow motor contact on the timer, the other lead will need to be unhooked from the neutral terminal of the timer and connect to the resistor. The other side of the resistor will have a wire go down and connect to the green ("4") side of the high limit.

 

 

The only down side is you won't be able to adapt the dryer to 120 volts in the future, but that may never be an actual issue.

 

 

 

[maytag85]

Wired it up that was as well, didn’t work either. Maybe I’ll look into it in the future, but leaving it as is since it ain’t broke. Guess these older dryers that use a double throw switch thermostat really weren’t designed to use a power dropping resistor.

I’ve literally tried different configurations, anything you can think of, came out with nothing.

Will probably put the power dropping resistor once I customize my Whirlpool dryer, along with my Whirlpool washer sometime this upcoming spring or summer.

 

[Chetlaham]

Buy yourself some class 00 gloves and a multi function meter. Test and trace. Divide and conquer. Something isn't hooked up right. Physics say it will work in the end.

 

Either way I respect what you're doing even if it means leaving the dryer the way it is. Nothing wrong in keep the original cycles and vintage function.  

 

[maytag85]

Just going to leave it as is since it functions perfectly in stock form. Just going to reserve the timed drying cycle for bulky bedding and smaller loads, auto dry will be used for everything else.

Was one of those ideas that sounded good in the back of my mind, but wasn’t really meant to be in reality. Just going to leave it alone for now.

 

[bajaespuma]

I know that a lot of old GE dryers had timers that went up to 140 minutes to accommodate installations where the unit was modified to run on 115v instead of 230v. IIRC opting for the lower voltage meant that most loads took 3 X longer to dry.

 

They even had a connection under the rating plate where the consumer could reconnect leads to run the Automatic cycle on the lower voltage.