Why did my HWH thermostat(s) fail?

[hevykevy420]

Setup: 50 gallon electric HWH w/240V digital timer, dedicated return line/Taco 009 recirculation pump w/timer & aquastat control

Problem: Recirc pump ran continuously, lukewarm "hot"water, then, no hot water upstairs at all .

I replaced the heating elements thinking they went bad. Turns out replacing the thermostats restored the HW and now the recirc pump kicks off when the return line is up to temp. HW is also hot again and not lukewarm.

When replacing thermostats, I noticed part of the plastic separating the poles inside the digital 240V timer melted and the wire looked black on its sheathing . The timer still works fine (tested on/off voltage from timer and to HWH) but I disconnected it anyway because of the damage. Didn't want to risk any bad wiring.

It looks like something maybe shorted the unit causing the damage and maybe frying the thermostats. What would cause this? Or, would the continual running of the recirc pump overload the timer box? I may discontinue using a timer as I think the cycling of the recirc pump might put too much strain on the unit with the continual hot/cold cycles.

Any insight into what went wrong here? The HWH is only 6 years old. The Home Depot plumbing expert said power surges happen all the time and probably caused this but I thought I'd ask the true experts here.

[havasu]

What brand of recirc pump do you have? The Grundfos takes very little voltage, so I doubt this is your problem. Power spikes, yes, this occurs all the time. I smoked a TV, Stereo, my kids Kereoke (sp?) machine, and a Playstation once when I had a spike due to a faulty wiring job by an idiot contractor. Check your breakers and all the wires leading to your W/H and look for damaged, frayed or black (smoked) wires.

[hevykevy420]

The recirc pump is a Taco brand, I believe 009 model (bronze). The pump is wired for power completely separate from the HWH. I inspected the 30A breaker in the main box and no signs of damage were found (and it never tripped!). Only damaged wire was 240V input to timer, and I also noted some black/smoked wire at the timer to the HWH wiring underneath the metal HWH wiring cover. I removed all the damaged wire before reconnecting.

Well who knows, maybe it was a surge, i'm surprised the breaker never tripped if there was a short!

[havasu]

I'm not an electrician but I myself would replace that breaker. $25 would give you peace of mind!

[hevykevy420]

Thats great advice. I think I will take you up on that!!

THanks for the advice,

Hevy