Hot tub heater troubles

[Transient]

A year ago, I started up my hot tub in the fall and a day or so after getting up to temp, the GFCI breaker started tripping. After some experimentation, I found the problem was with the heater element. The failed unit was quite rusty looking, which I blamed on the SmarterSpa Drape Over SWG (or more accurately, the salt).

So I ordered a replacement element, installed it and went back to using chemicals instead of salt. All was well with the heater right up until I drained the tub in the spring.

Now I started up my hot tub and once again, a day or so after getting up to temp, the breaker has started tripping. Once again, it seems to be the heater element. I took a multimeter and found there's 10 Ohms between the two connectors, but also 10M Ohms between the connectors and ground.

Am I just unlucky or do I have something else going on?

 

[RDspaguy]

Heater lifespan is 99% chemistry. I've seen cheap incolony elements last 10 years and titanium elements last 3 months.
Improper draining/winterization and start-up procedures can damage equipment, including heaters.
Installation errors can cause early failure.
Low flow or low water conditions can damage elements.
Any issues are more likely to occur at start-up after a fresh, cold fill. Gaskets shrink from cold, plastics get brittle, and everything runs for 12 hours straight to get it up to temp. If there's anything waiting for an excuse, it got one. Including your breaker, which could have been damaged by tripping from the last bad heater.

 

[Transient]

Thanks, I appreciate the perspective and things to consider.

I am pretty diligent with the chemistry. I regularly test with my Taylor test kit and never neglect it.

For installation of the replacement heater element last year, I followed the directions exactly, including applying the specified torque. Admittedly, I am not a pro, but I do feel I did it correctly.

It does make sense that the startup would be hard on the heater, running for many hours. It does seem strange to me that it would fail a couple days after this -- if it has failed. I'm not really sure if 10M Ohms between the connectors and ground is considered failed, although I suspect it should read open/infinity and any leakage will trip the GFCI.

I also wondered about the breaker, however it only trips when the heater turns on. There's a pilot light for the heater circuit which lights up for a split second before the GFCI trips. I disconnected the heater and it's been running without tripping since Wednesday.

 

[RDspaguy]

am pretty diligent with the chemistry. I regularly test with my Taylor test kit and never neglect it.

All due respect, but that's what everyone thinks. Or at least tells the repair man (me). What most do is correct their problems once a week, which is not the same as having good chemistry. In fact, the correction can be more damaging than the problem.

followed the directions exactly,

Who's directions? What brand of controls?
The modern "standard" heater element can be damaged by contact with the heater tube, failure to secure terminal post while installing, seepage at the o-ring from corrosion or error, vibration from pump issues, improper bonding/grounding (in certain circumstances), but if it lasted a year it's probably chemistry.

am not a pro, but I do feel I did it correctly.

I once had the owner of a plumbing company buy an element and had his master plumber install it. A week later he's demanding a new element because we sold him "junk". I explained it was likely installation error and got my butt chewed for 10 minutes for even suggesting such a thing.
So I told him I would come out and replace the element and if I could not show him the mistake his guy made I'd warranty it, otherwise he's getting charged. He didn't say a word as he wrote me a check.
Again, no disrespect, but assurances are meaningless to me after 27 years of hearing them. I know you think you did a good job, everybody thinks they did a good job, and every once in a while they actually did. Sadly, trying and succeeding are not the same thing.

not really sure if 10M Ohms between the connectors and ground is considered failed,

Any ohms between terminal and ground is failed.

only trips when the heater turns on.

The heater is the biggest electric load in the tub at 24 amps. Often it is more than everything else combined. A gfci damaged by tripping gets hot under load which causes the trip. The more load, the more hot, the more likely and sooner the trip.

If I had to guess a non-chemistry cause I'd say you probably got the element too close to the tube wall which trapped debris and created a hot spot. That and failure to hold the terminal to avoid twisting while tightening the nut are the 2 most common installation errors. Both will destroy the element after a while.

 

[Transient]

I understand your point of view and why years of having people lie or fabricate the truth would make you a skeptic. I get the same sort of thing in my line of work.

I really have no way to prove what I'm saying other than to say there's absolutely nothing for me to gain by misleading you or anyone else. I am here to learn and hopefully understand what went wrong so I can avoid the same problem in the future, not to make a warranty claim.

Again, I appreciate your advice and insights.

Any ohms between terminal and ground is failed.

I did notice something strange, which I don't understand. I cleaned the area around the electrical contacts/posts, then retested, and it showed infinity. It didn't help though, the GFCI still trips, and afterwards it's back to reading 10M ohms. The test is repeatable, clean and it goes back to infinity until it's started again. Visually the area looks clean and dry, it's not leaking from the seals or anything like that.

Who's directions? What brand of controls?
The modern "standard" heater element can be damaged by contact with the heater tube, failure to secure terminal post while installing, seepage at the o-ring from corrosion or error, vibration from pump issues, improper bonding/grounding (in certain circumstances), but if it lasted a year it's probably chemistry.

The directions that came with the replacement heater element, Therm Products 25-41341L. Below is a photo I took last year before installing it. I also watched a few videos on YouTube before proceeding.

It went into a C2550-2300ET heater housing made by RMF. The control board is a Correct Tech Mini Max CT250.

If I had to guess a non-chemistry cause I'd say you probably got the element too close to the tube wall which trapped debris and created a hot spot. That and failure to hold the terminal to avoid twisting while tightening the nut are the 2 most common installation errors. Both will destroy the element after a while.

Seeing the photo again, I do recall at that time having some challenges with keeping the element centered while applying the specified torque. It took me several attempts. The replacement element sat a lot closer to the top of the tube than the original, making it very unforgiving of any amount of twisting at all.

That low-profile element was all I could find locally. Even today, it seems that's all that's being sold in Canada.

I'm going to drain it today and remove the heater assembly so that I can have a look at it.

 

[RDspaguy]

people lie or fabricate the truth

Not what I was saying. People think they are doing a good job because they go do it and have clear water, but the truth is that testing and balancing once a week is still 5 out of 7 days of poor chemistry.

it's not leaking from the seals or anything like that.

Yes it is. Just not enough to see.
On the element there is an epoxy seal around the post which insulates the conductor from the sheath of the element. While tightening the terminals it is crucial that you put a wrench or such on the post beneath the connections to prevent ANY twisting of the post. If it moves 1/64 of an inch it has damaged the epoxy and will seep, eventually shorting out. You are gaining a momentary reprieve by cleaning it off.
Also, when installing the element into the tube the terminals can catch on the contours of the tube and bend if forced. This will also break the epoxy seal.

The directions that came with the replacement heater element,

Never seen a replacement element with instructions before. You do realize that the element you have and the one in the instruction sheet are not the same, right? Depending on the tube design and sensor placement this one might be a problem.

some challenges with keeping the element centered while applying the specified torque.

I put one handle of my channel locks in the tube to brace the element while tightening. A screwdriver works too, just be careful not to scratch it.

That low-profile element was all I could find locally. Even today, it seems that's all that's being sold in Canada.

I can't speak for the canadian supply chain, but that element is virtually unused in modern tubs. I carried one around for most of a decade after ordering it for a job that cancelled. Never did see another tub that could use it. The standard is the balboa style, which is pictured in the instructions, and has better clearance on the tube and sensor. I strongly recommend finding the right element this time. A search on amazon for "6-flo spa heater element" returned pages of offers from $20 to $40 US. I would recommend the titanium one.