fixing my dishwasher

My dishwasher stopped heating the water so I checked the heating element resistance and I get 13 ohms.

Well the manual asks that it be plugged in to at least a 15 Amp circuit and at 120 Volts I get R = V / I or 120/15 = 8 ohms just to get a ballpark of what it should be.

However, some website says that heating elements should be in the kilo-ohm range, so what is the error in my above thinking?

Reply to
rabbit killer
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First, there are different kinds of heating elements, but kilohms is not for a water heater element. The appliance will draw less than 15 amps, because there is a motor load and the circuit has to be over-rated for safety. Thirteen ohms cold sounds reasonable. It will increase some as it heats up, but at startup you'd have 120 V /13 ohms = 9.23 amps, or (120^2/13) = 1100 watts, which is reasonable. The problem must be somewhere else - there may be a series thermal breaker that has gone open-circuit, or the controller may not be turning the heater on, or there may be a problem in the wiring. Also, the dishwasher may have a setting to prevent heating the water, relying on the hot water supply to do the job. You might check that.

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John
Reply to
John O'Flaherty

I will check the series thermal breaker. I tested my toaster and it's 14 ohms, so I think the dishwasher element is fine.

Reply to
rabbit killer

Do you heat water with your toaster?

Reply to
Tom Biasi

Well, some of the water in the bread evaporates as it toasts, but was that really the point? A heating element of 13 or 14 ohms resistance is probably not defective, was the point.

Hope This Helps! Rich

Reply to
Rich Grise

Tom Biasi wrote On 09/20/2010 06:14 PM:

That's silly. I'm just trying to get an order-of-magnitude idea of what is a good number. This is a counter-top dishwasher and I suspect it uses about the same amount of power as the toaster. I was also trying to falsify the claim from the one website that said my heating element should be in the kilo-ohm range.

So now, I have the uh... "thermal breaker"? that was wired in series and is open. I'm guessing it should be closed until it reaches 90 C ("90 C BYDQ" is imprinted upon it).

My question now is: what do I google to find this part? "thermal breaker" is not working and I was wondering if there's a better name for it.

Reply to
rabbit killer

John O'Flaherty wrote On 09/20/2010 01:44 PM:

rst, there are different kinds of heating elements, but kilohms is

The

the "series thermal breaker" is, in fact, open circuit and I am looking to replace this part. However, when I google this I get a bunch of "thermal circuit breakers" which list their ratings in Amps, not degrees celsius. The only temp related one I could find was a "one shot thermal cutoff" which just melts at a certain temperature and is done.

Imprinted on this switch is "90 C BYDQ" Does BYDQ mean "By flow of heat"?

I'm looking for ideas of other words to google...

It takes in cold water, per instructions, and worked fine for many months before suddenly ceasing to work.

Reply to
rabbit killer

Contact a local appliance repair place with the brand and model, along with the markings on the part.

--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
Reply to
Michael A. Terrell

Yes Rich, But my point was to caution against thinking that all heating elements are the same. That's all, a gentle nudge. Tom

Reply to
Tom Biasi

rabbit killer Inscribed thus:

Before you start on the thermal breaker, disconnect the heater and measure the resistance to the case, only to make sure that the thermal breaker hasn't opened because of a ground fault. The heater could have a hole in the sheath. You should expect a reading of several megohms. A megger is a better instrument for testing this than a multimeter.

12 to 14 ohms is about right for a heating element. The device that you call "Thermal Breaker" is probably a protection device to prevent overheating and/or "Boil Dry" conditions. If so there will probably be a thermostat fastened to the tub to set the water temperature, either directly or via a timer.
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Best Regards:
                     Baron.
Reply to
Baron

Well I thought it was funny.. ;)

Reply to
1jam

--
I suspect that what you have is a "thermal fuse", which is a fusible
link which opens (and stays that way) when its temperature rating is
 Click to see the full signature
Reply to
John Fields

John Fields wrote On 09/21/2010 12:53 PM:

I found it! It's in the allied electronics catalog. It's a normally closed (open on rise) THERMOSTAT that will open at 190 F and close again at 172 F. There are many temperature choices... This thing is mounted very close to the heating element.

No I'm pretty sure this is circuit is made to break every time the dishwasher runs when the water is through heating.

Reply to
rabbit killer

t

es

nd

or it.

That's a one time fuse. It opens once. Sounds like there is some other problem in your washer. The heater stayed on too long... the fuse blew. Replacing the fuse will most likely cause it to fail again when you use the dishwahser. A local repair guy might be your best bet. (as someone suggested) They may know what typically fails in your brand of dishwasher.

George H.

Reply to
George Herold

--
Good find!

Got a link to pin-point it?
Reply to
John Fields

here is the link. it looks exactly like this - i have a pair of calipers and all the dimensions are the same. you have me second guessing myself because i think you are more knowledgeable but i'm pretty sure this is right. the one-time fuses look entirely different.

formatting link

Reply to
rabbit killer

George Herold wrote On 09/21/2010 01:51 PM:

okay, i just pulled something else out - there is what looks to me like a thermocouple but i will describe it: it is in a sheath .2 inches diameter and 1 inch long. it was located between the coil of the heating element. on the outside, there are two really thin-gauge leads going to the computer. eletrically, this component tests 'open' with my multimeter.

the thermostat was hooked up on the thick-gauge power in series with the heating element.

so is the thermostat back-up and the thermocouple tells the computer when to turn the heat off? or is it, like george suggests, a thermal fuse that just blew telling the computer to turn off the power?

either way, the thermostat is open which means it needs to be replaced. i will try again to get the manufacturer on the phone.

rK

Reply to
rabbit killer

I've had the same problem (a bad thermal cutout) - searched through Mouser, Newark, Digikey etc catalogs online - no joy. Then, I got hold of the appliance manufacturer's parts list. Bingo! They might call the part by some wierd name, but you can tell by the pictorial diagrams that it *is* the part you need.

Following Mike Terrell's post makes it even simpler!

Ed

Reply to
ehsjr

rabbit killer Inscribed thus:

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Actually not ! The device on you're dishwasher could be either. I have several physically identical devices to the one in your link, some are "non re-entrant" that is "not re-settable" thermal fuses.

I note that from another post that you have found another thermal sensor ! From the description you have given either device may be the one that is used for temperature regulation.

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--
Best Regards:
                Baron.
Reply to
baron

--
I'm guessing that the cylindrical component is a Normally-Open close
on rise thermal switch, and the other component is a thermostat which
 Click to see the full signature
Reply to
John Fields

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