Tweaking Whirlpool Automatic Dryness Control

tsteves5 · Apr 18, 2014

Good idea on the rear rollers. I will check them. I also plan to compare the volume of airflow through the heater box versus the blower. That will let me know if I have any other major leaks.

I had a meter connected to each thermostat when I tested them last night. That's how I know which ones were opening and when. It did also appear that the timer motor was only running when the thermostat was open and the heater was off.

combo52 · Apr 18, 2014

WP Dryer With Time-Temperature Auto Dry

A WP dryer like this should NEVER be cycling on the safety thromostat, this is an unsafe condition.

You have one or more problems, Toms suggestion about possible clogging of the lint screen should be checked, but I suspect that the real culprit is the long exhaust system. You may also have slightly higher voltage than 240 volts which will also cause this type of problem especially with anything less than an ideal vent, you may also have a safety thromostat that is failing [ they often become too sensitive before they fail ] I would change it.

Often when we have run in situations where the vent is long, voltage high etc I have installed a smaller heating element to make the dryer operate properly, improve durability of the heating element and most of all improve safety.

mrb627 · Apr 18, 2014

Is this dryer...?

Have the TOP lint screen or inside the dryer door lint screen?

Malcolm

tsteves5 · Apr 18, 2014

John - I will check the voltage too. Just out of curiosity, do you know the part number for a smaller heating element?

tsteves5 · Apr 18, 2014

Malcolm - It's a top lint filter.

tsteves5 · Apr 19, 2014

More Testing

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I tore down the dryer and cleaned it again. It is now completely lint free, even the inside of the blower housing and the blower blades. I also scrubbed the lint filter. It didn’t seem too bad but now you can eat off of it. There was maybe a cup of lint throughout the entire dryer. Most was in the bottom of the blower box. I found a couple of small air leaks. The first was where the lint filter box connects to the bulkhead. The foam had deteriorated. I replaced with new foam. The second was between the drum and the left side of the bulk head. I think the bulk head might have been bent a little. I fixed this too. I verified that the vast majority of the exhaust air comes through the heater box.

My exhaust duct is about 15 feet long. It is accessible from my basement. I took down the entire duct and cleaned it again. It wasn’t too bad either. There was about a half cup of lint in the entire duct.

I did test the line voltage. It’s 250.9 VAC. This means that I am running the 5200 W heating element at 5436 W, which is 4.5% higher. 

I now realize the error of my ways. I previously tested dryer cycling while the dryer was empty. This time, I dried a full load of wet laundry. The dryer cycled on the high-limit thermostat for about 60 minutes and then finished the rest of the time on the operating thermostat. I measured the temp of the heater box directly above the thermostat. It appears that the high limit is opening up at about 200 degrees. I believe the rated temp for this is 250, so it appears that I might have a weak high limit thermostat.

tomturbomatic · Apr 19, 2014

Good investigative work

You also have very high line voltage. You probably could get by with the smaller heater. John can give you the part no. That and a new hi limit thermostat should have your auto dry working properly.

How many elbows do you have in the vent run, 2?

tsteves5 · Apr 19, 2014

Thanks for the help everyone.

There are 4 elbows in the exhaust run. 1 elbow is a 90, the others are 45-ish.

I might change out the operating thermostat too. I have some concerns about the thermostat heater that I still want to investigate.

tomturbomatic · Apr 19, 2014

The elbows are the problem. If you read the installation instructions, you will find that the air flow is too restricted. 15 feet of vent is a lot even with one elbow.

tsteves5 · Apr 19, 2014

Exhaust Booster?

There isn't anything that I can do to shorten or straighten that exhaust run. Maybe an exhaust booster would help if I can find one that will fit.

tomturbomatic · Apr 19, 2014

Reread Combo52's post about using a smaller heater in dryers with long vent runs. It is simpler than using a booster fan. Vent booster fans require a special additional lint filter in the pipe. For situations like yours, Whirlpool made a dryer with a special blower that boosted the exhaust without compromising the airflow through the dryer.

tsteves5 · Apr 19, 2014

I'm definitely on board with a smaller heating element. Just kicking around some other ideas too.

If anyone knows the part number of the smaller heater, I'm all ears.

tsteves5 · Apr 21, 2014

!!!!!!!!!!!!!!!!!!!!!

I think the high limit thermostat did the trick. I changed it out, and dried a very large load. For the first time in the dryer's history the clothes were completely dry at the end of the automatic cycle. I monitored the thermostats. The new high limit thermostat never cycled once.

I think I will also add an indicator light that will illuminate if the high limit ever starts cycling again.

Tom/John/Malcolm/DADoES - You're awesome. Thanks for the help.

tomturbomatic · Apr 22, 2014

Wonderful news! I am glad for your success.

tsteves5 · Apr 26, 2014

I added a "check engine" light to the dryer. It comes on if the high limit thermostat opens up before the operating thermostat. It will help detect thermostat and air flow issues in the future.

kenmorebd · Apr 26, 2014

Cool I like that warning light! Good luck with dryer I think I have the same model as you, did your dryer ever make the high pitched"whistle" when the lint trap was getting full?

yogitunes · Apr 26, 2014

just in case you decide on a booster fan....a better alternative

tsteves5 · Apr 26, 2014

Lint Trap Whistle

Yeah, it has the whistle on the lint trap assembly. I think I've only ever heard it once.

Tweaking Whirlpool Automatic Dryness Control

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