Two heaters in two years

[DrNinjaman]

So, I just had the local pool service guy over to replace my second heater in under two years.
The first heater was probably/definitely because I started the spa dry during a water change like a moron a while back, but this one doesn't make a lot of sense. The service guy said it was probably because it's a saltwater tub, because the heating element and heat exchanger tube itself was significantly corroded. However, my understanding is that the level of salt in my water (1500 ppm with a Chlormaker) is unlikely to cause issues unless the pH gets low. My pH sits at 7.6-8.0 like a rock, and tends to slowly climb due to aeration. I've got about 190-200 ppm calcium, 60 ppm borates, and probably 18-20 ppm CYA.
I've had some issues controlling the swcg cell, which boil down to the fact that I was trying to run it with the cell tucked into the center of one of the return filters like a Nature 2 Mineral stick. The flow rates were either too high or too low and the chlorine levels inside the filter wouldn't reflect the bulk water of the tub, so would bounce around uncontrollably. Basically, I was manufacturing a bunch of headaches due to my insistence on placing the cell there. I think it may also be the source of the heater failure as well, combined with one other issue. By placing the cell at the water return, I was piping the high chlorine concentration from the cell directly through the circ system and the heater, which would seem to be undesirable in this light, correct? Chlorine being an aggressive oxidizer and all that? In addition to that, recently I had some bad luck with my cover when a huge mass of snow slid off of my roof on two separate occasions and smashed the structural integrity out of half of my spa cover, fully cracking and destroying one side. I have since replaced the insulation with a DIY foam pack I built up out of closed cell XPS insulation from Lowes and fit into the vinyl cover jacket, but I suspect it may still be a bit leakier than the original cover. This could lead to the heater running more than usual, causing more rapid corrosion.
I have discontinued placing the salt cell in the filter, and have been much more successful at keeping the chlorine levels steadily healthy, but that change was fairly recent, so high chlorine levels and chlorine direct injection into the heater remains my active hypothesis for the premature failure of the heater.
Any other possibilities I may be missing? We're pretty late on changing the water out right now, so maybe have a lot of stuff dissolved in there, would that be a problem? I know for a fact that the salt is still below 1600 ppm though.
Should I have my CYA levels higher? I was under the impression that spas didn't need much since they don't see the sun much, so I've always targeted 20 CYA as enough to buffer the chlorine but keep it easy to shock if necessary. That would make the chlorine more aggressive on the heater if it gets high though, wouldn't it?

 

[DrNinjaman]

Pictures of the snow attack and replacement foam insulation pack.

 

[Bperry]

So, I just had the local pool service guy over to replace my second heater in under two years.
The first heater was probably/definitely because I started the spa dry during a water change like a moron a while back, but this one doesn't make a lot of sense. The service guy said it was probably because it's a saltwater tub, because the heating element and heat exchanger tube itself was significantly corroded. However, my understanding is that the level of salt in my water (1500 ppm with a Chlormaker) is unlikely to cause issues unless the pH gets low. My pH sits at 7.6-8.0 like a rock, and tends to slowly climb due to aeration. I've got about 190-200 ppm calcium, 60 ppm borates, and probably 18-20 ppm CYA.
I've had some issues controlling the swcg cell, which boil down to the fact that I was trying to run it with the cell tucked into the center of one of the return filters like a Nature 2 Mineral stick. The flow rates were either too high or too low and the chlorine levels inside the filter wouldn't reflect the bulk water of the tub, so would bounce around uncontrollably. Basically, I was manufacturing a bunch of headaches due to my insistence on placing the cell there. I think it may also be the source of the heater failure as well, combined with one other issue. By placing the cell at the water return, I was piping the high chlorine concentration from the cell directly through the circ system and the heater, which would seem to be undesirable in this light, correct? Chlorine being an aggressive oxidizer and all that? In addition to that, recently I had some bad luck with my cover when a huge mass of snow slid off of my roof on two separate occasions and smashed the structural integrity out of half of my spa cover, fully cracking and destroying one side. I have since replaced the insulation with a DIY foam pack I built up out of closed cell XPS insulation froM Lowes and fit into the vinyl cover jacket, but I suspect it may still be a bit leakier than the original cover. This could lead to the heater running more than usual, causing more rapid corrosion.
I have discontinued placing the salt cell in the filter, and have been much more successful at keeping the chlorine levels steadily healthy, but that change was fairly recent, so my active hypothesis for the premature failure of the heater.
Any other possibilities I may be missing? We're pretty late on changing the water out right now, so maybe have a lot of stuff dissolved in there, would that be a problem? I know for a fact that the salt is still below 1600 ppm though.
Should I have my CYA levels higher? I was under the impression that spas didn't need much since they don't see the sun much, so I've always targeted 20 CYA as enough to buffer the chlorine but keep it easy to shock if necessary. That would make the chlorine more aggressive on the heater if it gets high though, wouldn't it?

Chlorine needs to be last thing entering the pool/spa through the returns. I don’t follow what you did but sounds like a possible cause.

How are you testing the water? The CYA test in the Taylor kit bottoms out at 30ppm doesn’t it?

 

[DrNinjaman]

Chlorine needs to be last thing entering the pool/spa through the returns. I don’t follow what you did but sounds like a possible cause.

How are you testing the water? The CYA test in the Taylor kit bottoms out at 30ppm doesn’t it?

I got the extended CYA test tube that goes down to 20 ppm. Plus I measure carefully how much dichlor I add when I do a new fill. It is possible the level has fallen since then as I don't check it regularly. Everything I've seen on here has said that I don't need much CYA for a spa though, since it doesn't get consumed by sunlight like it does in a pool and will just hang around indefinitely.

The Controlomatic Smarterspa chlorine cell is cylindrical in shape with a hole in the end, so it fits perfectly in the center of one of the spa filters that have an open center to allow the addition of a Nature 2 mineral stick.

Controlomatic also advertises an inline install for their swcg units, so I figured that if it was okay to have it in the plumbing , it was okay to have it at the start of the plumbing. Their inline install instructions don't make any mention of specific placement of the cell relative to the heater as being especially important to keep in mind, aside from not running main pump flow through it, but they aren't the most comprehensive instructions either. I have a 24 hour circulation pump that runs at a lower speed all the time, so it all seemed basically ideal. Putting the cell there was nice because it allowed easy access to the cell for the periodic acid rinsing Controlomatic recommends for maintenance of the cell, and it kept the cell out of the way for using the tub. But as I mentioned, it didn't work, it totally borked the device's sensor, and seems to have been undesirable from a corrosion of the operating components perspective. It took me a while, but lesson learned.

Controlomatic's in-line install manual page:


Now however, I'm concerned about possible damage to the spas's pumps, and if there is anything else I should be paying attention to to minimize progress of any internal corrosion.

 

[Bperry]

I got the extended CYA test tube that goes down to 20 ppm. Plus I measure carefully how much dichlor I add when I do a new fill. It is possible the level has fallen since then as I don't check it regularly. Everything I've seen on here has said that I don't need much CYA for a spa though, since it doesn't get consumed by sunlight like it does in a pool and will just hang around indefinitely.

The Controlomatic Smarterspa chlorine cell is cylindrical in shape with a hole in the end, so it fits perfectly in the center of one of the spa filters that have an open center to allow the addition of a Nature 2 mineral stick. View attachment 492290

Controlomatic also advertises an inline install for their swcg units, so I figured that if it was okay to have it in the plumbing , it was okay to have it at the start of the plumbing. Their inline install instructions don't make any mention of specific placement of the cell relative to the pumps or heater as being especially important to keep in mind, aside from not running main pump flow through it, but they aren't the most comprehensive instructions either. I have a 24 hour circulation pump that runs at a lower speed all the time, so it all seemed basically ideal. Putting the cell there was nice because it allowed easy access to the cell for the periodic acid rinsing Controlomatic recommends for maintenance of the cell, and it kept the cell out of the way for using the tub. But as I mentioned, it didn't work, it totally borked the device's sensor, and seems to have been undesirable from a corrosion of the operating components perspective. It took me a while, but lesson learned.

Controlomatic's in-line install manual page:
View attachment 492289

Now however, I'm concerned about possible damage to the spas's pumps, and if there is anything else I should be paying attention to to minimize progress of any internal corrosion.

CYA isn’t just a buffer from sunlight but it also buffers the harshness of chlorine. What have your chlorine levels been over the past couple years? I’m not familiar enough with that kind of system to comment except that everything I’ve read is that chlorine should not be added to the intakes of heaters or other equipment, partly because the pH is very low at that spot before it has a chance to dilute in the water.

 

[DrNinjaman]

CYA isn’t just a buffer from sunlight but it also buffers the harshness of chlorine. What have your chlorine levels been over the past couple years? I’m not familiar enough with that kind of system to comment except that everything I’ve read is that chlorine should not be added to the intakes of heaters or other equipment, partly because the pH is very low at that spot before it has a chance to dilute in the water.

Yeah, I know the CYA is a harshness buffer, that's why I start each fill with dichlor to add the CYA and then switch to the SWCG supplemented with bleach after I get to 20ppm on the CYA. I'm just wondering if I should aim a little higher.
The chlorine levels have been all over the place, and have been quite high on occasion, as high as 19 ppm in the past. That's not typical though, putting the cell inside the filter mostly tended to always see some residual chlorine around the cell, even when the bulk water read 0 FC. With the timed cell, I've been pretty good at keeping the chlorine level between 2 to 5 ppm. I did notice a nick in the cell cable insulation the other day, so maybe the water's getting extra electricity.

 

[DrNinjaman]

I just checked my Pool Math logs, the dry fire damaged heater was replaced on October 17th, 2022. So this latest heater has only lasted 7 months. The local pool service guy indicated that swapping the whole heater module would be a $400 - $500 job out of warranty, so I'm going to have to learn to do that one myself if this keeps up. Looks pretty straightforward, the spa has shutoffs on either side of the heater tube, two twist collars, and the tube just plugs into the control board. They keep replacing the heater with the same model, which I'm sure isn't titatnium. One thing that has been different from this heater to the last was the previous winter I had been turning the spa heat down to about 80 degrees during the week most weeks, and I have hardly done that this last winter, so the spa was probably running the heater substantially more. And the water was 20 degrees warmer, which would accelerate any chemical processes.

 

[ajw22]

What model heater are we discussing? Please put it in your signature.

I assume you run the spa and heater in the winter. Your problem could be corrosive condensation...

Heater Condensation - Further Reading

www.troublefreepool.com

 

[DrNinjaman]

What model heater are we discussing? Please put it in your signature.

I assume you run the spa and heater in the winter. Your problem could be corrosive condensation...

Heater Condensation - Further Reading

www.troublefreepool.com

It's a Balboa 58083 5.5 kW 240V 800 M7.
Aside from all my mucking around with where I put the cell, my experience has been very similar to this thread:

Hot tub heater corrosion

So we just got a hot tub in December of 2021. Over the past year, I’ve learned a lot about hot tub water chemistry and have gotten really good at it. We bought a saltron mini and have used it for a year. Everything seemed great! Then last week, the breaker kept tripping and we couldn’t figure...

www.troublefreepool.com

 

[ajw22]

I thought you had a gas heater. Forget the corrosive condensation comment.

Lets see what @RDspaguy thinks about the Balboa 58083 5.5 kW heater.

 

[RDspaguy]

was trying to run it with the cell tucked into the center of one of the return filters like a Nature 2 Mineral stick.

source of the heater failure

piping the high chlorine concentration from the cell directly through the circ system and the heater

Exactly.

the heater running more than usual, causing more rapid corrosion.

Not really so you'd notice.

so maybe the water's getting extra electricity.

A salt cell works by passing current through the salt water, producing chlorine from the salt. Theoretically, all (or 99.9%) of this current should stay within the cell. If faulted to water in the cord it could, theoretically, go anywhere depending on the location in relation to the cell and heater. But current in the water will find ground at the heater housing.
Theory is wonderful, and looks great on paper, but reality is seldom limited by it. And reality says that dropping a power source into a tub of water with multiple possible paths for current flow creates a parallel circuit, or branch circuit, which has equal voltage present on each branch and current flow is determined by branch resistance (in this case distance through water) and ALL branches (including your grounded heater) will get some current flow. So there will be a trace current leaving the water in the heater housing. This can, theoretically, cause damage to the housing, most likely in the form of tiny lightning-bolt like "tracks" etched into the heater flanges, if the current is high enough.

running the heater substantially more. And the water was 20 degrees warmer, which would accelerate any chemical processes.

Theoretically...
Yes, heat is a catalyst, and chemical processes in a spa effect the heater the most, but this is such a small variable in the overall life of a heater I doubt it is even a factor. I've seen these heaters last 2 months here and 20 years there.

swapping the whole heater module would be a $400 - $500 job

Which is why you replace the element only when it's out of warranty. Much of that $400 is parts. A titanium element is under $100.

 

[Methuselah]

Nice job on the cover, but perhaps if covered by homeowner insurance all you would have to pay for is the deductible? New covers can be very expensive and factory replacements even more so (get estimate on factory, purchase aftermarket).

 

[DrNinjaman]

Nice job on the cover, but perhaps if covered by homeowner insurance all you would have to pay for is the deductible? New covers can be very expensive and factory replacements even more so (get estimate on factory, purchase aftermarket).

Quote on a factory replacement extra thick cover for that spa was $1100 4-6 week lead time. I made that foam pack for $100 and four days of cutting and gluing. As long as the vinyl cover is still intact, I'll be doing that until I can finish my design for an aluminum faced insulated structural panel cover with manually cranked telescoping corner posts. Like a Corvana cover but more pop-up camper tech.

 

[DrNinjaman]

Exactly.

Not really so you'd notice.

A salt cell works by passing current through the salt water, producing chlorine from the salt. Theoretically, all (or 99.9%) of this current should stay within the cell. If faulted to water in the cord it could, theoretically, go anywhere depending on the location in relation to the cell and heater. But current in the water will find ground at the heater housing.
Theory is wonderful, and looks great on paper, but reality is seldom limited by it. And reality says that dropping a power source into a tub of water with multiple possible paths for current flow creates a parallel circuit, or branch circuit, which has equal voltage present on each branch and current flow is determined by branch resistance (in this case distance through water) and ALL branches (including your grounded heater) will get some current flow. So there will be a trace current leaving the water in the heater housing. This can, theoretically, cause damage to the housing, most likely in the form of tiny lightning-bolt like "tracks" etched into the heater flanges, if the current is high enough.


Theoretically...
Yes, heat is a catalyst, and chemical processes in a spa effect the heater the most, but this is such a small variable in the overall life of a heater I doubt it is even a factor. I've seen these heaters last 2 months here and 20 years there.


Which is why you replace the element only when it's out of warranty. Much of that $400 is parts. A titanium element is under $100.

I appreciate the reply, this is certainly worth considering. I bought the salt cell because the spa came originally with the frog @ease system and that was stupid expensive and also difficult to actually monitor. My water looked like crud. Once I found this forum, I was convinced to ditch that mess and switch to either just bleach sanitation or a salt cell. The salt cell certainly has appeal from the automated nature of it, making it easier to maintain the spa especially when we're out of town or otherwise busy, and they seemed like they were similar in terms of TCO.
From a sanitation only standpoint, the salt cell and the bleach/dichlor TFP method were about equivalent in terms of long term costs for supplies, and both were hundreds of dollars cheaper than the frog system on an annual basis. That said, if the cell is causing accelerated failures of the spa machinery, that shifts the TCO calculation, doesn't it?

So, thus far this forum has provided excellent advice on saving money on water management chemicals and how to properly balance the spa water. I even like the Ahh-some system flush stuff for when we drain and fill the thing, though I was skeptical given how black box proprietary the stuff is.
On the other hand, I probably wouldn't have been encouraged to buy a salt water cell without the various reading I did on the forum either, so if my pumps go to heck next year, I'd probably be net negative on TCO compared with just sticking with the frog system the whole time.

 

[DrNinjaman]

Would a sacrificial zinc anode potentially address this problem?

Also, just a matter of nomenclature, but I've heard people refer to their spa heater as a heat exchanger, but my spa definitely just has a heater. A gas fired spa would have a heat exchanger, because it's transferring heat energy between two fluids, but that Balboa unit is just a resistive coil immersed in the water directly, right?

Theoretically...
Yes, heat is a catalyst, and chemical processes in a spa effect the heater the most, but this is such a small variable in the overall life of a heater I doubt it is even a factor. I've seen these heaters last 2 months here and 20 years there.

Why else would the heater be most affected by corrosion if not because it gets hot? I get the point about the variability of the life of the part, but you said it yourself, chemical processes in the spa affect the heater the most. That has to be primarily due to the high temperatures involved. And yes, I'm familiar with the difference between theory and reality. I'm a mechanical/structural engineer by training and employment so I'm familiar with preparing for the unexpected. The difference between theory and reality really comes down to variables though. Have your theory account for them all and there shouldn't be any difference. Which is why saying that theory and reality often don't match and then saying variation in water temperature probably doesn't matter is incongruous.
Why are salt systems worse for corrosion in spas than pools? Spas are 20 degrees hotter maybe? I wouldn't discount temperature effects like that out of hand. The chlorine consumption definitely changes between 80 degree water and 102.

We have a situation that is not fully understood, namely why some spas with salt water systems have corrosion issues, and I'm just trying to evaluate any differences I have had in the operation of my spa between the two heaters that it has had. We received it June 30th, 2021 and ran it without issue until October 17th, 2022 on the original heater, 16 months. I then fried that heater by letting it turn on dry because I have to occasionally do dumb things to keep my life interesting and to give the rest of you a chance. The service guy only replaced the heating element at that time. The replacement heater failed after 7 months. so quite a bit more quickly, and the service guy replaced the whole tube this time because he said it was excessively corroded. After the first replacement, something was buzzing in a very irritating fashion with the circ pump running too, so I wonder if there may have been something questionable with the install itself. I suspect the buzz was due to the heater tube touching the plastic case around the control board in a way that it did not when it was new from the factory. It eventually stopped making the noise, but it took months. I only saw the second failed heater briefly, but I recall the electrode connections with the epoxy showing corrosive buildup around them on the outside of the tube. When the tech only replaced the heating element the last time, he would have had to tighten the power wires onto those posts, correct? That operation is somewhat more sensitive than just resealing the split collars and attaching some plugs, yes?

I wonder is if it would help if the salt cell and the heater explicitly ran at different times?

 

[RDspaguy]

Which is why saying that theory and reality often don't match and then saying variation in water temperature probably doesn't matter is incongruous.

Read it again. I said that, while temp causes increased chemical effects on the heater (notably calcium scale) in comparison to other parts in the spa, this is a minor factor in the lifespan of the heater. Ph and high oxidizer levels are the main factors, and will destroy your heater regardless of temperature.

Why are salt systems worse for corrosion in spas than pools?

What makes you think that? Comparing a portable spa to a pool is like comparing a camper trailer to a brick house, but I've seen a salt system take out a gas pool heater in under a year. Warranty was void for using a salt system, and it actually caught fire and melted vinyl siding nearby. You hear more problems with spas because they have more stuff to be effected by poor chemistry.
But if you drop a chlorine feeder (which is what a cell is) in any pool skimmer and send high concentration chems through your equipment, you'll damage your equipment.

The chlorine consumption definitely changes between 80 degree water and 102.

Which is why bromine (which handles higher temps better) was the go-to for spas for 50 years. Don't blame the disadvantage of the chemical being used. Chlorine is also destroyed by sunlight (uv) and ozone, in addition to high temps.
But I am no chemist, I'm a repairman and can only tell you what I've seen in my 26 years of fixing spas. If you want to see me alot, drop a chem feeder in your skimmer. It's been proven to my satisfaction many times over.

I wonder if there may have been something questionable with the install itself.

It's possible. If the element touches the tube wall it will burn out, but in much less than 7 months. If it were just ALMOST touching, maybe close enough to rattle the side as it vibrates in the current (all flo-thru elements do), who knows. But it is possible. A failure of this type is visibly obvious, so do you have the old element?

would have had to tighten the power wires onto those posts, correct?

Yes, and if he failed to secure the post bolt while tightening the nut it can twist the post, crack the epoxy seal, and seep water eventually shorting out. Typically less than 7 months as well, but it is dependent on how much damage was done initially.

 

[DrNinjaman]

Read it again. I said that, while temp causes increased chemical effects on the heater (notably calcium scale) in comparison to other parts in the spa, this is a minor factor in the lifespan of the heater. Ph and high oxidizer levels are the main factors, and will destroy your heater regardless of temperature.


What makes you think that? Comparing a portable spa to a pool is like comparing a camper trailer to a brick house, but I've seen a salt system take out a gas pool heater in under a year. Warranty was void for using a salt system, and it actually caught fire and melted vinyl siding nearby. You hear more problems with spas because they have more stuff to be effected by poor chemistry.
But if you drop a chlorine feeder (which is what a cell is) in any pool skimmer and send high concentration chems through your equipment, you'll damage your equipment.

Which is why bromine (which handles higher temps better) was the go-to for spas for 50 years. Don't blame the disadvantage of the chemical being used. Chlorine is also destroyed by sunlight (uv) and ozone, in addition to high temps.
But I am no chemist, I'm a repairman and can only tell you what I've seen in my 26 years of fixing spas. If you want to see me alot, drop a chem feeder in your skimmer. It's been proven to my satisfaction many times over.


It's possible. If the element touches the tube wall it will burn out, but in much less than 7 months. If it were just ALMOST touching, maybe close enough to rattle the side as it vibrates in the current (all flo-thru elements do), who knows. But it is possible. A failure of this type is visibly obvious, so do you have the old element?


Yes, and if he failed to secure the post bolt while tightening the nut it can twist the post, crack the epoxy seal, and seep water eventually shorting out. Typically less than 7 months as well, but it is dependent on how much damage was done initially.

Fair enough. I wasn't getting that you considered the high chlorine concentration injected into the plumbing and the pH levels as the most significant contributors. Not having a pool, the comments about "don't put chlorine tablets in the 'skimmer'" have gone over my head until just now. The skimmer is the water return on a pool, duh.
That was my own suspicion as well, but I'm just guessing based on some 100 level college chem classes many years ago.
Regarding the "pools tolerating salt better than spas" statement, that was just based on some comments I had seen elsewhere on this forum, not my own experience, so I will gladly retract that assertion.
Anyway, regarding my own situation, I think I will give this SWCG one more try with the following adjustments: based on my understanding of the function of CYA in spas as a chlorine buffer, I'm going to run with the CYA a bit higher, 25-30. This will make it easier to verify the level too, as my kit can measure those concentrations easily. I'm going to repair the nick in my cell's cord insulation and make sure to keep it out in the middle of the tub when it's running. After rereading chem geeks chlorine guide, I'm also going to work on keeping my pH closer to 7.6-7.8. It likes to creep up to 8 - 8.2, but I think I've been driving most of that due to my insistence on keeping the TA around 80, which I've been doing because Poolmath says normal TA is 50-90. It has seemed strange to me in the past to often be adding muriatic acid and baking soda at basically the same time.
And I'll probably follow Joyful Noise's advice and slap a little dielectric grease on the heater terminals just for good measure.

 

[Methuselah]

It has seemed strange to me in the past to often be adding muriatic acid and baking soda at basically the same time.

Less is always more, you add acid to bring down your TA --- just don't add so much that you need the baking soda. I've never needed to raise TA (or use baking soda), aeration pretty much assures that.

 

[DrNinjaman]

On a related note, what's the deal with heater parts prices? If I search for 58083 balboa 5.5kw spa heater I get numbers all over the place. The basic direct replacement assembly, tube, collars, heater element, and sensors with the plug pigtails, vary from like $400 from a parts site that specifically mentions these as Artesian Spa replacement parts, to like $150-160 from other places like Amazon and such. Is this a factory label vs. aftermarket knock off situation? Do those price differences and or brand/supplier matter?
Whole assembly plus titanium element has similar ranges of prices. I'd like to know so that once this thing is out of warranty, I can just fix it myself.

 

[RDspaguy]

The controls, and therefore heater, are Balboa parts, but Balboa does not make them, they get the elements from an element manufacturer and install them into tubes made by someone else with sensors and fittings made by yet another vendor. They then sell them to spa manufacturers, often with custom proprietary details (such as an artesian label). Everybody who touches it marks it up, so artesian is more than balboa is more than Related Metal Fabricators, even though it's the same element. Where your particular supplier gets them, and how many they order, determines the retail price.
I have not seen a knock-off balboa heater, but I'd try one if I found it.
Under warranty, some manfs do not have elements or even assemblies as they only buy complete control systems, so these replace the WHOLE CONTROL PACK under warranty, as they are just returning it to balboa as purchased.