Dryer keeps blowing fuses

[nola mike]

Have a whirlpool stackable washer/dryer unit. I'm just about to replace it, since I'm tired of screwing with it. It keeps blowing the thermal fuses, and I have no idea why. There are 2 non-resettable safety fuses, 1 in the heater assembly, 1 near the blower motor. Both will occasionally blow. I've replaced all the cycling fuses and thermostats multiple times as well, and have even bench tested them to make sure they cycle properly. No exhaust obstruction, all the seals look OK, blower motor is clean. Threw in the towel and had a repair guy come out. He replaced the element (thought there might be an intermittent short--the old one tested ok cold) to no avail. Any other ideas?

 

[gm280]

I can understand your frustration, Maybe it is time to buy a new one. While I love fixing things myself. Reoccurring problems some times are hard to locate.So peace of mind will cover the initial new cost and a newer model will be a little more energy efficient as well... JMHO! :noidea:

 

[JaCrispy]

First off, congrats on tackling home appliance repair. Internet forums are a wealth of info. Fixed my drier a few times at the cost of about $10. Don't have an answer for you, but try Googleing your model number and seeing what comes up on repair forums. Most of the time is a common repair/problem.

 

[nola mike]

Yeah, I've done everything I can think of. Frustrating thing is that the damn system is so simple. If the cycling stats are working correctly (and they are), the dryer should never get hot enough to trip the others. Only thing I can think of is if the dryer overheats too quickly, before the cycling stats have a chance to turn off. Of course, the problem is intermittent. Will sometimes go months without happening.

 

[Grub54891]

How long is the vent run?
Also we had one do that quite often, eventually found where a mouse had chewed slightly through the incoming power feed,dangerous! Luckily the power feed went through a cement block wall,and it did not start a fire. Took awhile to find it,I just happend to see a spark one day while walking past. That dryer had no fuses of its own,inside the unit,just the breaker in the panel.but I could see the short causing a surge upstream and doing that.

 

[bruceb58]

How long is the vent run?

My thoughts exactly. Biggest reason dryers over heat is bad venting.

That is why on both dryers I have in 2 of my houses, I have booster Fantech fans.

 

[Grandad]

I'm curious as to why the fuses would hold for several months and then randomly blow. Do you know if your voltage from the utility supplier varies much? Do your light bulbs flicker or blow prematurely? If you're in an isolated area, perhaps on an older distribution system, upgrades to the system can raise the transformer secondary voltages where "taps" have been previously set on the high side to compensate for inadequacies. Once distribution improvements are made, the taps could require resetting. Anyway, if the voltage is too high, amperage of circuits in your dryer could be above original specified values and cause fuses to blow. - Grandad

 

[Tim Frank]

According to Ohm's Law (I haven't heard it was repealed.... ), higher voltage would produce lower current.

I'd suspect voltage drops... or the venting.

 

[bruceb58]

According to Ohm's Law (I haven't heard it was repealed.... ), higher voltage would produce lower current.

Assuming resistance stays the same, higher voltage=higher current.

Of course that is besides the point since these are thermal fuses and they blow with high temps, not high current. That is why I suspect a venting issue.

 

[Grandad]

Assuming resistance stays the same, higher voltage=higher current.

Of course that is besides the point since these are thermal fuses and they blow with high temps, not high current. That is why I suspect a venting issue.

My theory: Higher voltage means higher current, meaning higher wattage or BTU's. More heat could cause thermal fuses to blow. - Grandad

 

[bruceb58]

My theory: Higher voltage means higher current, meaning higher wattage or BTU's. More heat could cause thermal fuses to blow. - Grandad

Of course the thermostat should take care of the higher heat anyway if it was a voltage issue. Highly doubt its a voltage issue of any significance.

 

[Grandad]

According to Ohm's Law (I haven't heard it was repealed.... ), higher voltage would produce lower current.

Hi Tim. I wasn?t going to take issue with your comment, but I don?t want members to be misguided. In its simplest form, the Ohm?s Law formula for current flow (amperes) in a circuit is equal to voltage divided by resistance (ohms). So, if the voltage varies by a given percentage, the current will also vary by the same percentage and in the same direction, not inverse as you stated. Short of complicating things by including a discussion of electromagnetic induction of the drive motor, the impedance (resistance) of the machine never changes. So no, as you stated, Ohm?s Law hasn?t been repealed (or amended).
- Grandad

 

[Scott Danforth]

When was the last time the vent was brushed out? I get about 20# of lint every 6 months out of my 20' vent tube to the roof. If I don't clean the vent every 6 months, the dryer eventually hits a thermal limit

 

[nola mike]

Of course the thermostat should take care of the higher heat anyway if it was a voltage issue. Highly doubt its a voltage issue of any significance.

Exactly. That's what's so weird. Even a venting issue should be taken care of by the thermostat I would think. It isn't a venting issue though. I replaced the vent with rigid, and it's a straight run maybe 2 feet to the exterior wall. Also thoroughly cleaned the entire air path starting at the dryer intake.

 

[Tyme2fish]

When was the last time the vent was brushed out? I get about 20# of lint every 6 months out of my 20' vent tube to the roof. If I don't clean the vent every 6 months, the dryer eventually hits a thermal limit

Yes, check your air flow throughout the vent from the dryer through the outlet.

 

[nola mike]

See above post...cleaned and then replaced the vent. 2' straight horizontal run.

 

[Tim Frank]

Lost track of this thread. Deserved some....took some.....
I always love seeing some clown weigh-in with a correction and then get it wrong themselves....not as much when I do it, but I still chuckle.

My logic was the Ohm's law formula P= I*V .... so if voltage drops, current must rise to supply the same power..
It seems there is a conflict/contradiction between that and V=I/R that is beyond my abilities to resolve. Never thought of that before.

I'm not 100% convinced, but am not going to argue with electrical engineers. I've only got a 100 level electrical physics course and do my own home wiring, but I did not stay at a Holiday Inn Express last night.

Any serious imbalances on the main panel? i.e. are both legs fairly evenly balanced?

 

[nola mike]

Ended up replacing the dryer. Moved the electric dryer from my house to the rental (where the problem dryer was), then installed a newer gas dryer at my house. Read my other post about the hilarity that ensued when I ran the new gas line...

 

[Grandad]

Hi Tim. You?re on the right track. Remember that the only thing constant is the machine?s opposition to current flow (ohms). Power (watts) is not a fixed value, but is a result of how much voltage you apply. You?ve recognized the difference in the 2 formulas that results in the power rising exponentially as the voltage rises. If you double the voltage, you get double the amps and get a result of 4 times the watts. On 240 volt circuits, utilities (around here) are allowed a tolerance of plus or minus 10 volts, but sometimes stuff happens and the voltage rises beyond that.

If the dryer?s design spec is 28 amps at 240 volts, its resistance must be 240/28 = 8.57 ohms
The manufacturer?s design wattage at 240V = V x A = 240 x 28 = 6720 watts

The same machine having a resistance of 8.57 ohms when an increase to 250V is applied:
A = E/R = 250/8.57 = 29.17 amps
Wattage produced = V x A = 250 x 29.17 = 7292W (a 572W increase or 8.5% above manf design spec)

The same machine having a resistance of 8.57 ohms when an increase to 260V is applied:
A = E/R = 260/8.57 = 30.34 amps
Wattage produced = V x A = 260 x 30.34 = 7888W (a 1,168W increase or 17.4% above manf design spec)

- Grandad

 

[ondarvr]

I've had it happen when the wife dries blankets, not every time, but more often when she over loads it with a large one.