Water heater element going bad multiple times over a month

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Sierrasparky

Senior Member
Location
USA
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Electrician ,contractor
Hey does anyone have any experience with water heater element going bad.
I recently replaced the lower element of a 2 year old water heater. The lower element was badly blistered. Replaced with new and now that one went. Now it went again. It is grounding out. There is little scale and the dip tube is in place. Electrical connections are good.
Tank was filled and bled before turning on.
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
Hey does anyone have any experience with water heater element going bad.
I recently replaced the lower element of a 2 year old water heater. The lower element was badly blistered. Replaced with new and now that one went. Now it went again. It is grounding out. There is little scale and the dip tube is in place. Electrical connections are good.
Tank was filled and bled before turning on.

The first "low hanging fruit" question that comes to mind: is the Line voltage at the water heater within a few volts of the voltage rating of the new element?
 

JFletcher

Senior Member
Location
Williamsburg, VA
If supply voltage is okay, I'd check the thermostat, and if that's good, check with the manufacturer to see if there are any known problems with that model burning out elements prematurely.
 

luckylerado

Senior Member
I have to change my lower one out about once a year and suck out all the Lyme buildup. My tank does not have a clean-out so I have to break it up and suck everything out through the element hole. Talk about a pain in the butt. The upper has never failed on me but it gets changed at the same time.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
If you are using the proper voltage elements then my bet is crud buildup in the bottom of the tank. Are you having to clean it out after replacing the element? I cannot imagine what else would destroy the element. I have a well and my element generally last as long as the water heater itself. I do use an acid neutralizer which probably helps with keeping the tank clean of crud
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
The first "low hanging fruit" question that comes to mind: is the Line voltage at the water heater within a few volts of the voltage rating of the new element?


Voltage within limits 233

If you are using the proper voltage elements then my bet is crud buildup in the bottom of the tank. Are you having to clean it out after replacing the element? I cannot imagine what else would destroy the element. I have a well and my element generally last as long as the water heater itself. I do use an acid neutralizer which probably helps with keeping the tank clean of crud

No crud in the bottom , however scale on the element about the thickness of paper after 2 weeks!
 

JFletcher

Senior Member
Location
Williamsburg, VA
Voltage within limits 233



No crud in the bottom , however scale on the element about the thickness of paper after 2 weeks!

Is it possible the t-stat is set so high/faulty that the element is boiling the water, at least locally? If the element is rated for 240V, driving it until it boils the water could cause rapid heating in spots as steam is a poor conductor of heat, causing "The lower element was badly blistered" you mentioned in your first post.
 

GoldDigger

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Location
Placerville, CA, USA
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I think that would best be determined by measuring the water temp. It clearly does not go high enough to trip the relief valve.
OTOH the blistering could be the result of very high local heating as the failing wire develops thin spots.
Most heaters have the option of installing 208V elements to avoid the high power loss from using a 240 element at 208. If the originals were 208 and you used exact replacements you would have a problem.
 

JFletcher

Senior Member
Location
Williamsburg, VA
I think that would best be determined by measuring the water temp. It clearly does not go high enough to trip the relief valve.

True, and you'd think that would be amongst the complaints... that said, tub mixing valves often have scald-guard tech, and perhaps they run dishwater hot and cold at the same time and do not notice. If the t-stat were right at boiling, it could still cause localized boiling that would not trip the pressure relief valve (or maybe it is, and the overflow is piped in such a way that the HO doesnt notice it.). Like you wrote, measuring the hot water temp tho would be prudent imho.


Most heaters have the option of installing 208V elements to avoid the high power loss from using a 240 element at 208.

How does a purely resistive load suffer from being supplied by undervoltage? In a water heater element designed for 240V but being fed by 208V (not the case here as OP has 233V), wouldn't it theoretically last longer? (and run longer too, however the total BTU for a given amount of water would be the same, yes?)

Would a 208V heating element burn out in a month if supplied by 233V?

eta: scale on the element after just two weeks could drastically affect its heat transfer ability, causing it to burn out prematurely.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
True, and you'd think that would be amongst the complaints... that said, tub mixing valves often have scald-guard tech, and perhaps they run dishwater hot and cold at the same time and do not notice. If the t-stat were right at boiling, it could still cause localized boiling that would not trip the pressure relief valve (or maybe it is, and the overflow is piped in such a way that the HO doesnt notice it.). Like you wrote, measuring the hot water temp tho would be prudent imho.




How does a purely resistive load suffer from being supplied by undervoltage? In a water heater element designed for 240V but being fed by 208V (not the case here as OP has 233V), wouldn't it theoretically last longer? (and run longer too, however the total BTU for a given amount of water would be the same, yes?)

Would a 208V heating element burn out in a month if supplied by 233V?

eta: scale on the element after just two weeks could drastically affect its heat transfer ability, causing it to burn out prematurely.
The typical temp/press relief valve is set for 150psi and 210F. So it might well hold when the tank temperature is high enough to allow local boiling at the element.
Scale is a factor, but I am not sure what the OP describes is that bad. This is water-soaked probably porous scale.

And the element will not suffer from under voltage but a 240V element at 208V will only produce 75% of the heat, which could affect refill rate for long showers even if it does not limit overnight heating.
As for what would happen with a 208V element at 233? It might very well fail in a month, especially if it low quality to start with or there are other contributing factors such as scale.

If the HO has very hard water, then a softener might be necessary to protect the water heater.
 
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