Melted wire nut on water heater

[KWill316]

About 6 year old water heater reinstalled again after a house remodel 2.5 years ago. Never had any issues.

3 weeks ago, I noticed we had no hot water. Checked it out and found the breaker was tripped. I flipped it back and it worked fine.

2 weeks ago, we started having electrical issues. It's one of those "smart" ones with a brain and heat pump. It kept turning on the heat pump every 3 minutes even though it was set on electric mode. We thought it was dying so we decided to replace it. When we went to disconnect it, one of the wire nuts was completely melted and the red wire from the water heater was melted back about 2 inches and completely green with corrosion. I don't have a photo of that.

We cut the wire way back to where it was clean and installed a new wire nut using the same connection that it had before. It worked fine until yesterday. This is in simple electric mode. We didn't try the heat pump mode because I'm afraid the brain is messed up anyway.

Yesterday, I was walking by it and smelled burned plastic. The wire nut on the same wire was melting and smoking. I am attaching photos of it.

I'm trying to figure out what can cause this and what to do next. Do we need to replace the water heater or should we call an electrician to see if we have problems with wiring? We don't have much extra $$ right now so I would appreciate some advice. I'm very concerned with this causing a fire so we will do what we have to.

 

[Jadnashua]

To generate enough heat to melt the wire nut, there has to be some resistance to the connection there, which acts like a heating element (resistor). Is the wire nut actually spec'ed for the size wire used? When there's a poor connection, the actual voltage that gets to the unit goes down, the connection heats up, and the amount of current it tries to draw will go up, making it worse (until the CB trips, if it gets high enough).

 

[Sponsor]

 

[Dj2]

Have it checked by an electrician, you may have a short, wrong gauge wires or something else.
Money well spent, considering what can happen otherwise.

 

[MACPLUMB]

You have a short in one of your elements or a thermostat, at this point get a new water heater

 

[hj]

quote; You have a short in one of your elements or a thermostat, at this point get a new water heater

Do you ALWAYS replace water heaters instead of making simple repairs?

 

[Dana]

Replacing "... one of those "smart" ones with a brain and heat pump..." can be an expensive proposition, and repairing one might not be cheap either, but it's worth a shot.

Most heat pump water heaters came with 10 year warranties, there may be some financial relief available if the wire nut connection was done at the factory, not by the installer.

What make & model?

 

[KWill316]

Thank you for all the replies. I have contacted an electrician who came highly recommended by my friends. He said it's the water heater. Something is causing it to short (either the electrical connection or the brain). I also found out that the water heater model that I have was discontinued a year after they launched it due to many "brain" problems. Instead of putting more money into a bad unit, I'm going to replace it with the "dumb" water heater. This one hasn't saved us any electricity (like they claimed) and I don't want to replace it with another one that will just have more parts to break.

 

[Dj2]

I think under the circumstances, you are making a wise decision. Generally, you want your water heater to last a little longer, but some do fail immaturely, it's beyond your control.

 

[MACPLUMB]

quote; You have a short in one of your elements or a thermostat, at this point get a new water heater

Do you ALWAYS replace water heaters instead of making simple repairs?

SEE follow up post by O.P.
I think that with a direct short like showed by the electric burning the wire not once but twice shows that there may be
possible hidden wire damage inside jacket that next time "COULD" cause a fire, !
and for this reason I recommended replacement I have probably repaired as many water heaters as you have over the years as not only a plumber but also as a prime service agent for all the national water heater MFG's

 

[Master Plumber Mark]

You probably need a new water heater or at the very least
you need new elements and new t stats on the unit....

or you can gamble and just Throw a little duct tape on it and forget about it....

Sorry, but I did not read all the way through your post to see you also have
a heat pump on top of this unit... That makes it even more fun to attempt
to make repairs to it.....

I honestly doubt anyone either in plumbing or
in an electrical background will want to mess with one of those dogs.
they are nothing but trouble and a waste of money right out of the box.......

 

[Ballvalve]

You could do a lobotomy on that rig [disconnect the bad brain] and bypass the worthless cheap Indonesian heat pump, trouble shoot the elements and find if one is bad. It might be the compressor sucking the juice and overheating the wire. What is the amp rating on the breaker for this in the panel? Or for less than $200 bucks, get the cheapest water heater made and change the anode rod to a longer and better one. With a good anode and maintenance, I get 10 to 20 years out of my water heaters.

 

[Jadnashua]

The wire nut should not melt as long as it is tight and the circuit breaker is working properly. You need some special equipment to verify that a CB is working properly, but a loose connection at a wire nut, especially if the wires are corroded, will act like a resistive heating element, and can get quite hot.

 

[Homestead_John]

Is the red wire in your picture the "source" wire? If so, it looks aluminum in the above picture. It could be a bad connection due to the expansion and contraction of aluminum under load. Having a similar issue instead my air handler at the moment. Do you have the option to replace that run with copper wire?

 

[hj]

Heaters are usually labeled "connect to copper wires ONLY", for just that reason

 

[Phog]

Late to this discussion. But wanted too my $0.02. It's interesting that only one of the wire nuts -- but not both -- appeared to be experiencing the melting problem.

If your wire nuts are installed properly, this narrows down the location of what is likely a short to ground to somewhere along the red wire itself, or else to a section of the heater element relatively closer to the "end" that the red wire connects up to. This would be because the series voltage drop across the element allowed less ground current to flow through the black wire than through the red wire.

You probably could have repaired the unit by replacing the faulty element, but to be safe you also would have had to at least inspect/replace the red wire all the way through the unit. Its insulation could have gotten melted/damaged in other more hidden places as well. And who knows what other electrical components got stressed in the process. I think you made the right choice to replace the thing.