Pentair Heater Corrosion Issue Help

[jasonhaefner]

My pool is just over seven years old, and I'm on my second heater and fourth heat exchanger; initially, I thought I was not maintaining my levels properly, but now I am convinced something is very wrong and cannot find answers, so I'm looking for some opinions.

Saltwater pool with the Pentair Intellichem system; I take water to my pool company weekly; here are results from last summer (2023 tab):

Pool Chemistry Tracking

I started with a Pentair Mastertemp with the copper heat exchanger and went through three of them in four and a half years. So, I decided to get the Pentair Mastertemp with the cupro-nickel heat exchanger about 2 years ago, and I always test water at least weekly (results from last summer above). My pool company also installed two anodes to help prevent corrosion in the heat exchanger, and I've attached pictures of my setup. They just added the air intake on the side of the heater to see if that helps, they think it could be condensation forming on the exchanger causing corrosion.

After installing the cupro-nickel heat exchanger in 2022, I started noticing little copper/blue/green particles in my pressure side vacuum screen catchment, and i thought it was the anodes coming apart. It turns out it was the brand new cupro-nickel heat exchanger, and it went out after a little over a year. I had a new heat exchanger installed at the beginning of 2023, but the amount of copper coming through tells me it will leak very soon.

NOTES:
1) I know there is not a check valve between the heater and salt cell, my pump runs 24/7 at 2000 rpms so the pool company told me I do not need a check valve. I am going to have one installed anyway.
2) I have two anodes installed, and neither corrode at all, which should mean my water is stable and not corrosive.
3) I shut the system off 3-4 times a week to clear the basket, so water can back up into the heater at that time.

At this point, I'm wondering if having the heater so close to the air conditioner could be the issue?

I could be missing something with the water, but I cannot figure out what it possibly could be.

I'd love any/all theories people may have, as I just want to figure this out and not have to go through heat exchangers every 1.5 years.

 

[kul]

Welcome! Sounds like your water chemistry may be off and you are running low ph perhaps? What test kit are you using? What have you been adding regularly to the pool?

My heater developed a leak from several low ph occasions from pucks in skimmer from previous owner and their love for adding MA (as was explained to me by previous pool guy when we first moved here)

Here’s some reading to get you going:
Test Kits Compared
Pool Care Basics
PoolMath

 

[pjt]

I thought I was not maintaining my levels properly, but now I am convinced something is very wrong and cannot find answers

First and foremost, how are you testing?

I know there is not a check valve between the heater and salt cell, my pump runs 24/7 at 2000 rpms so the pool company told me I do not need a check valve. I am going to have one installed anyway.

You don't need a check valve between the heater and SWCG. (If you had a tab feeder, you would need one.)

I have two anodes installed, and neither corrode at all, which should mean my water is stable and not corrosive.

Anodes do little to nothing for your pool.

I could be missing something with the water, but I cannot figure out what it possibly could be.

Your symptoms suggest poor water chemistry, specifically low pH. What chemicals are you adding to your pool? Post complete water test results from a recommended kit.

TFtestkits.net

tftestkits.net

 

[ajw22]

What model pump?

What model filter?

Do you have minerals in that big grey canister?

Where does your Intellichem inject the acid into your plumbing?

Your pictures are not useful. They are too small to zoom in and see any detail.

Heat exchangers wear due to low pH or high water flow eroding the copper.

 

[TopJimmy]

Once you get a good test kit you can be certain of your chemistry. There is also another source of corrosion that it could be and the Pentair manual speaks to this. You have to maintain no lower than a constant 68 deg. Any lower and highly acidic byproducts of combustion form and it will quickly destroy your heater. Personally, I maintain 70 deg to give a buffer.

 

[jasonhaefner]

Some answers, It is a 100% Pentair system with Intellitouch and all that automation:

1. My pool company does the testing using a Taylor kit and some automation, I take water in at least weekly: The 2023 tab in this spreadsheet has all weekly results, Ph has been between 7.3 and 7.8 the entire year. All chemistry is here:
   • Pool Chemistry Tracking (This is the full spreadsheet of test results. The 2023 tab is all of last year. These are the full chemistry readings from my pool company and were verified by me - we both use Taylor test kits).
   • I also test using a Taylor kit to verify that their readings match.
   • They have no clue why this is happening and do 100% of my water testing.
2. The flow is 2200 rpms 24/7 and goes up to 2700 rpms when the heater kicks in and 2900 rpms for two hours each morning for the vacuum and 2800 when we use the slide or fountain.
3. The grey canister is a Nature2 Professional Purifier Vessel.
4. The pump is a Pentair IntelliFlo Variable Speed High Performance Pump VS+SVRS 3hp
5. The sanitizer, salt call and acid injection tank are all after the heater, prior to returning to the pool.
6. The filter is a Pentair cartridge filter.
7. After 2 weeks when we open the pool and get chemistry in line, we then turn on the heater and keep it at 75 degrees+ the rest of the year to avoid the condensation/corrosion potential. Bit it runs for about two weeks a year with cold water (55-65 degrees).
8. The pool company put that indoor air intake tube on my heater last year as a last attempt to help, thinking that air intake too close to the AC unit was causing issues, I know it's ridiculous.
9. I'm on well water, if that matters.

All I can think of is the flow is eroding the heat exchanger. My anodes (I know they don't help) get zero corrosion and look like new after a year of being installed. I thought it has to be chemistry, but based on my readings and the pool company testing, all using Taylor kits, the chemistry is ideal 99% of the time.

Last thing, my heater is about 4" from one of my AC units; it passed the code in my town, but it is really close to that AC unit - could something the AC does cause some weird condensation or other issues with airflow on the heat exchanger?

Better pictures:

 

[ajw22]

Where is Bigdog72 located? Your location matters for some of our advice.

The Nature2 Professional Purifier Vessel is putting minerals including copper and silver into your pool that will accumulate in the pool water and can cause staining. We do not recommend the use of any mineral system.

Is all of your equipment and pool bonded?

Has anyone checked for voltage gradients between the bond wire and equipment or ground?

 

[jasonhaefner]

Where is Bigdog72 located? Your location matters for some of our advice.

The Nature2 Professional Purifier Vessel is putting minerals including copper and silver into your pool that will accumulate in the pool water and can cause staining. We do not recommend the use of any mineral system.

Is all of your equipment and pool bonded?

Has anyone checked for voltage gradients between the bond wire and equipment or ground?

I'm so sorry about that location; that was an old username - I just fixed it.

I'm in Frankfort, IL, northern IL. I understand the Nature2, I may have it pulled out when I get work done again.

I know it is all grounded with copper, BUT I will check the voltage gradients, I have not done that.

 

[ajw22]

I'm in Frankfort, IL, northern IL. I understand the Nature2, I may have it pulled out when I get work done again.

Do you drain down and winterize your pool? Draining for the winter dumps some of the metals and reduced the likelihood of accumulating to staining levels.

However you should still have it pulled. It does nothing good for you.

I know it is all grounded with copper, BUT I will check the voltage gradients, I have not done that.

It may be a terminology slip but bonding is different then grounding. The pool bonding should not be connected to any electrical grounds.

Bonding vs Grounding

Electricity and water don't mix. Learn a few basic tips how to keep your family safe when dealing with electricity around your pool.

www.troublefreepool.com

 

[Lake Placid]

Heater appears to be bonded correctly as that’s the side of the bonding lug on the Mastertemp. If the rest of the bonding is intact is a question for the OP to explore.

 

[jasonhaefner]

We drain it below the return lines and winterize it, then refill it to prevent the liner from getting water under it. I have some wrinkles in the liner from draining and not refilling the first few years as we have a high water table, and I did not know water could cause wrinkles in the liner.

All of the bonding appears to be intact. I have checked, as has the pool company, but I have not checked the voltage.

Father-in-law is an electrician, and he is coming by to make sure I check that properly.

 

[ajw22]

The heater is a MasterTemp 400?

What is the CFM of your house gas meter?

 

[jasonhaefner]

The heater is a MasterTemp 400?

What is the CFM of your house gas meter?

Mastertemp 250HD, I will check the CFM, I have no idea on that.

 

[ajw22]

Mastertemp 250HD, I will check the CFM, I have no idea on that.

More likely your gas service is properly sized for a 250 but you should check.

 

[pjt]

Where is the acid injection point? I couldn't pinpoint the location on the pictures.

 

[jasonhaefner]

Where is the acid injection point? I couldn't pinpoint the location on the pictures.

The acid injection point is after the salt cell, immediately before the water returns to the pool.

Attached is a picture of the heat exchanger degrading; it flakes off into those little copper/cupro-nickel flakes. That is a bag of dirt and organic matter from my vacuum; it is full of copper/cupro-nickel (blue/green flakes); it flakes like that all year, but this spring, it seems even worse.

Not sure if the way it flakes helps with a diagnosis.

 

[ajw22]

I would open up the heater now and remove the manifold to look into the heat exchanger tubes. With that amount of copper flaking there should be visible damage seen in the tubes.

At about 9 minutes into the video they have the manifold removed exposing the heat exchanger tubes...

And in this video they do a complete heat exchanger replacement...

Do you have any pics of what your damaged heat exchangers looked like?

I wonder if those copper flakes are from your heater or from copper in the water from the Nature2 reacting with calcium scale in the heater?

 

[1poolman1]

My pool is just over seven years old, and I'm on my second heater and fourth heat exchanger; initially, I thought I was not maintaining my levels properly, but now I am convinced something is very wrong and cannot find answers, so I'm looking for some opinions.

Saltwater pool with the Pentair Intellichem system; I take water to my pool company weekly; here are results from last summer (2023 tab):

Pool Chemistry Tracking

I started with a Pentair Mastertemp with the copper heat exchanger and went through three of them in four and a half years. So, I decided to get the Pentair Mastertemp with the cupro-nickel heat exchanger about 2 years ago, and I always test water at least weekly (results from last summer above). My pool company also installed two anodes to help prevent corrosion in the heat exchanger, and I've attached pictures of my setup. They just added the air intake on the side of the heater to see if that helps, they think it could be condensation forming on the exchanger causing corrosion.

After installing the cupro-nickel heat exchanger in 2022, I started noticing little copper/blue/green particles in my pressure side vacuum screen catchment, and i thought it was the anodes coming apart. It turns out it was the brand new cupro-nickel heat exchanger, and it went out after a little over a year. I had a new heat exchanger installed at the beginning of 2023, but the amount of copper coming through tells me it will leak very soon.

NOTES:
1) I know there is not a check valve between the heater and salt cell, my pump runs 24/7 at 2000 rpms so the pool company told me I do not need a check valve. I am going to have one installed anyway.
2) I have two anodes installed, and neither corrode at all, which should mean my water is stable and not corrosive.
3) I shut the system off 3-4 times a week to clear the basket, so water can back up into the heater at that time.

At this point, I'm wondering if having the heater so close to the air conditioner could be the issue?

I could be missing something with the water, but I cannot figure out what it possibly could be.

I'd love any/all theories people may have, as I just want to figure this out and not have to go through heat exchangers every 1.5 years.

View attachment 568473View attachment 568475View attachment 568476View attachment 568477View attachment 568478

What is the type of pool you have? Vinyl? Fiberglass? Plaster? It makes a difference.

 

[jasonhaefner]

Thanks for the replies; I've been out of town and finally back.

Vinyl pool.

I am 99% sure the flakes are from the heat exchanger; I will get pictures this weekend to verify. The Nature2 is after the heater, so I always assumed it would not have a huge impact as its always flowing into the pool.

The flakes are consistent all year, and every 1.5 years (max), I have had leaks in the heat exchanger. I have the pump running 24/7, but I turned it down from 2200 rpms to 1900 rpms to see if that helps reduce the friction on the heat exchanger.

The odd thing is, my anodes (I know they don't help, but I have two before the heater as I've been at my wits end), get zero corrosion, they have minor build up on them after a year, but still look solid. I would think that if my water was corrosive, it would eat through the anodes in addition to killing my heat exchanger.

When I open the pool, the water chemistry is good after about 1.5 weeks, and I test and adjust every 3-4 days until it's dialed in; then it's very consistent and tested/adjusted weekly. I have the intellichem ph and orp probe, BUT I only use them as a safeguard and never rely only on their readings. They do manage my muratic dosing and salt cell/chlorine generator, but testing shows my pH and chlorine are fairly consistent.

 

[ajw22]

Post a complete set of test results from your test kit in the format:

FC
CC
pH
TA
CH
CYA