Element noise

[jeremy2027]

Yesterday I accidentally dry fired my element. My resistance measures 10.2 ohms the same as my other element. My element seems to be making a noise similar to bubbling or popping when at full power. I don't remember it doing this in the past but I could have missed it the system is brand new and only one batch has been ran through it. It is holding temp correctly and ramp times are great. The element is a 5500w all stainless camco running at 240v.

 

[bruce_the_loon]

Noise can indicate that the metal surface has cracked or the insulating packing around the resistance wire has been disturbed by the overheating. Cracking would allow water to penetrate and that could be dangerous, disturbed insulation may not be a major issue unless it's allowing the resistance wire to come into contact with the metal cladding. That should be tripping GFCI breakers though. You could try and measure the resistance between one of the terminals and the metal cladding to see if there is contact. It should be an infinite resistance if there is no contact.

Are you able to physically examine the element surface for signs of cracks or surface damage? If the surface is still intact, then you might be lucky and the element is still good. It might have a shortened life though.

 

[jeremy2027]

I can't get a good look all around the element due to the terms coil I will check the resistance. The only thing I checked was across the two hot leads which were 10.2 ohms and hots to ground which were open.

 

[jeremy2027]

OK looks like I lucked out. Nothing is shorted out and what was causing the boiling popping noise was when the element dry fired the outer conductor has no gap between the folded over part of the element. This was causing the water in between the element to boil. I spread everything apart and all sounds well. I'm sure the lifespan of the element has been shortened but only time will tell. Thanks for your help.

 

[bruce_the_loon]

That's good news. Quick question, how long did it run dry and did you dump water on it to cool it down? A couple of minutes on a new element probably won't affect it much.

Cooling an overheated element is an interesting task, the best is to rapidly cover it with already boiling water to minimize the thermal stress on the metal. Hitting it with cold water can cause the metal to twist and buckle, especially with a folded element where there already stresses on the folded areas. Letting it air-cool might be less damaging than cold water, it certainly is for an overheated frying pan. Seen the base of a frying pan deform into a Z shape when someone dumped it into a sink of cold water.

 

[jeremy2027]

Im guessing it went a minute or two then tripped the gfci due to heat Im guessing since nothing is grounded out. It was at 500+ degrees when I checked it on my fluke IR meter. I just let it cool down to 90 degrees or so and transferred 150* water that I had going in my boil kettle to test it out (after I ohmed it out of course) I got LUCKY. It does speak a whole lot for a ULWD element though Im a fan for sure now. I just cant be a bonehead anymore.