Above Ground Salt water pool with SWG- heater has copper exchanger- corrosion

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H

hystat

0
Aug 14, 2017
7
ON, Canada
we have a Raypak 106a heater (copper HE) on our new this year 12x24 above ground resin salt pool using the Hayward turbo? generator system (higher salt one - seems to run around 3000ppm. . I have no anode to protect the heater and no check valve as some youtubers (that Steve guy mainly) recommend.

Should we have an anode and or check valve?

There seems to be 3 sort of areas where this is discussed in addition to these components- confusing me.
1. bonding loops. first of all, Well. I have no issue with bonding the pieces together, but why? they all use 3 prong cords and the "ground" (bonding) prong of each component is all bonded where they all plug into the same receptacle box. So they already are bonded. That 3rd pin is attached to the metal housings of each appliance. The neutrals all meet each other at the receptacle too. So I can't see how there can be any voltage potential between any two.
I can run another ring of copper but I say it's redundant.

2. driving ground rods... well this I won't do. It's clearly against the Canadian Electrical code to ground any branches of a residential electrical system. The only place the bonding path can be earthed per code is at the service entrance where the neutral is jumpered to the bonding bus. Are people worried about lightening or something? I don't get why anyone would drive rods at the pool.

3. Zinc anodes. There are pucks that go in the skimmer. I don't get how this would do anything when that zinc is by itself in a plastic tub. Then there are in-line systems that plumb in and connect to the bonding loop. Well now we're maybe talking...seems like it might do something to save the copper in the Raypak. not sure it isn't scare tactics.


Another thing about the Raypak heater. I'm pretty sure it has an automatic bypass When the heater isn't on, is any saltwater flowing through the copper? I suspect not. so do we need a check valve to prevent the backflow of chlorine?
for the 40 or 80 hours or so a year the heater is on, do we care about the copper? I guess whatever was in the core when the bypass closes stays in there.

I see rust on the stainless screws on our ladder - makes me wonder.
 
:wave: Welcome to TFP!!!

There is no need for a check valve after the heater and before the SWG.

1. You are confusing bonding and grounding ... they are different. The plugs are grounding and the neutrals are related to the electrical wiring. The bonding protects you from stray currents by keeping all conducting surfaces around a pool at the same equipotential level. This is NOT attached to any part of the electrical system.

2. I do not think there is a need for driving grounding rods unless you have a panel on a separate building ... at least in the US. Not sure what you need up there.

3. I am not sure about this. Although I think you would want the ones that connect to the bonding loop. But, most pools do not have these and you likely really do not need it. The heater is at a MUCH higher risk of damage from the pH being kept too low.

Yes saltwater is going through the copper heat exchanger ... ALL the pool water will be salt water. The SWG needs to be after the heater and that is where the NaCl will be split to sodium and chlorine. No need for a check valve because the SWG will only generate when the pump is one and you have water flow.

There are different grades of metals .... all SS hardware is not the same and some corrodes easily.
 
jblizzle said:
:wave: Welcome to TFP!!!


1. You are confusing bonding and grounding ... they are different. The plugs are grounding and the neutrals are related to the electrical wiring. The bonding protects you from stray currents by keeping all conducting surfaces around a pool at the same equipotential level. This is NOT attached to any part of the electrical system.
Click to expand...

I know quite well the difference between bonding and grounding, and that 3rd prong on a 3 prong plug is a bonding pin even though people call it the ground. If you look inside the casing of any metal housed appliance or machine that has a 3 prong plug (guitar amp, fridge, kettle etc), that 3rd prong, and it's green wire are always bonded to all metal housings, hardware and any metal parts that are connected to the metal housings. Including my Raypak, the green screw is on the burner plate tray which screws to the metal chassis. There's nothing electrical about that 3rd prong, as it only connects to the metal parts and nothing electrical. Only during a fault where hot wire touches metal does that 3rd prong become a path tho carry current and pop the breaker (hopefully :))


The reason I was considering a check valve is one of the youtubers says the SWG can still give off residual chlorine when it's off and that can back up into the heater if you have your pump on a timer. We do because we have time of use rate changes here for electricity.

Our SWG was actually not on that timer for the first couple of months until I called Hayward and asked why the "no flow" light didn't work. (you could see and smell chlorine around the water return nozzle) The guy told me the above ground pool systems don't use a flow switch so they generate chlorine whether there's flow or not. He said the panel just still has the light because it's a universal circuit board they use. So word to the wise, if you have the Hayward SWG for above ground and your pump's on a timer, make sure the timer shuts down your SWG too. When I read the manual for the Hayward SWG, it spouts the wrong info and describes the operation of the flow switch for in ground systems.

I think I have to turn off the youtubes and listen to common sense. and take Hayward manuals info with a grain of salt (see what I did there?... lol)

- - - Updated - - -

and thank for the welcome! My wife wanted a pool and I knew I'd quickly become the pool boy and resisted for years, but now that it's in, I enjoy it and want it to last and be reliable.
 
A check valve between the swg and the heater is just not required. The reason a check valve is recommended between a trichlor tablet feeder and a heater is because the trichlor results in very acidic water and that low ph is what would damage a heater. An swg does not create acidic water and a little bit of chlorine and high pH is not going to damage the heater.

I also recommend you take a look at that link above because you certainly are still misunderstanding the difference between the electrical grounding and what bonding means around a swimming pool.
 
PSA: I just want to reinforce that bonding and grounding are two different things as it relates to swimming pools. The third prong of a 3 prong plug/outlet is NOT for bonding and does not serve that purpose as defined for swimming pools. Getting bonding wrong for a pool can result in electrocution and needs to be well understood and taken seriously.

More here, Pool School - Bonding vs Grounding

hystat,
Welcome to TFP! Don't mean to dogpile you here but electrical safety is very important. We hope you enjoy TFP! :)
 
jblizzle said:
A check valve between the swg and the heater is just not required. The reason a check valve is recommended between a trichlor tablet feeder and a heater is because the trichlor results in very acidic water and that low ph is what would damage a heater. An swg does not create acidic water and a little bit of chlorine and high pH is not going to damage the heater.

I also recommend you take a look at that link above because you certainly are still misunderstanding the difference between the electrical grounding and what bonding means around a swimming pool.
Click to expand...

Are you guys talking to Jblizzle or me?

I'm totally aware of the differences between bonding and grounding and there are no grounds here at my pool. The only ground on my property is at the south end of my house's foundation where two ground rods are buried and a #6 bare wire runs into the panel and connects to the bonding buss and jumpers to the neutral. That's where the daisy chain of all 3rd prong bonds connects to ground. It is the ONLY place they can go to ground legally.

Everything else in my house is BONDED, not grounded. The 3rd prong on all of my receptacles is bonded back to the main service panel's green buss bar. That bar then is jumpered to the #6 ground wire and earth.

So, everything that has a 3rd prong is bonded. TOGETHER. not grounded. I think you guys may be confused because a lot of people call that 3rd pin a ground, but it has nothing to do with ground until the main service panel.

I suppose a redundant bonding loop is for ladders and other metal parts people might have that don't normally have a connection to the bonding path but everything at an above ground pool already does. at least mine anyways. My heater is bonded, my pump is bonded and the SWG is bonded.
 
so I went to that page everyone wants me to read and it says exactly what I'm saying.

Maybe it's a Canadian vs. American thing.

In Canada, bonding is the 3rd pin and all metal parts, raceways, and metal conduit. Grounding is the connection to the earth.

In a receptacle, that 3rd prong is bonded to every other 3rd prong in every other receptacle in your house. Inside the heater, pump and SWG, that 3rd prong is bonded to the metal case and all metal housings. Don't believe me? open up your heater or pump and you'll plainly see it.

So everything is already bonded folks.

The fact that that bonding loop is then ultimately grounded in your main service panel does not change the fact that they are all bonded together.
 

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We are correcting your statement. What you are referring to is grounding. It is the same in the US as it is in Canada. The ground loop does not cover the pool deck, metal frame (for above ground), the water, ladder, railing or other items within reach of the pool water.
 
Welcome to tfp! Here's an excellent article and diagram regarding equipotential bonding for pools:
http://iaeimagazine.org/magazine/2017/03/14/taking-the-mystery-out-of-equipotential-bonding-requirements-for-swimming-pools/

Remember that saltwater is more conductive than regular h20, and that stray current from a swg alone, not to mention anything else in your grid, could be deadly. Its worth the curve to be rock solid on how this works.

I also wanted to give a very mildly dissenting opinion about check valves, swg and heaters. The vast majority of TFPers hold the belief it is entirely unnecessary. Even pool installers will agree. It is commonly accepted wisdom that a check valve is not necessary.

But I did once haved a conversation with a Raypak engineer who held the belief espoused in your YouTube video. Since you're contemplating all this, and check valves are cheap and easy to install, in your shoes I'd install it anyway. While backflow in a pressurized system may be minor, I'm not entirely convinced it doesn't play a role in some settings.

I have a new Cupronickle Raypak and I've been exploring the source of chelated copper scale shed from my swg. Jury is out, as I also have metals (well water, iron, and old copper pipes in source water, plus sequestrant use that causes chelation). But since you're starting anew, why not err on the side of exchanger preservation, even if you're among the minority ;)

Lastly, zinc anodes are considered equally controversial in these parts. I have an inline one made by pooltool, connected to my bonding system. There is no question that it corrodes, as a less noble metal should. Jury is out as to whether it does much protectively speaking but I elected to be in the minority on this one too ;) I feel that if sacrificial anodes are to work at all, they're best plumbed inline and bonded. I have no confidence that throwing a zinc plate in a skimmer basket does anything other than leech zinc into your water ;)
 
But the water coming out of an swg is not low ph and is not a high chlorine concentration. I cannot see how it could impact a heater even if it was possible for some of that water to somehow go against the flow.
 
Hi guys.
I just called Raypak to see what they'd say about this and asked for someone with technical depth on the topic. The guy I talked to cited possible backflow of chlorine gas generated right before the pump shuts down as the reason that their guidance to techs is to install a check valve on swg installations specifically. He pointed out that on page 24 of the installation diagram for series 206-406 the drawing specifies the check valve and the writing suppots same, though I'm just on a break so haven't done a deep read.

He is unsurprised that 2 local installers here claim otherwise as he feels this is a common oversight despite his efforts to educate same.

So maybe its a cya (not the chemical but the covering one's butt phenom) or maybe its technically germane - I remain neutral on the finer points. But its good enough guidance for me to implement a check valve, particularly when I am getting copper she'd from somewhere and have never used any copper containing products ;)

BTW, I was also given to understand that water does still communicate with the exchanger when the heater is off, just at a different flow rate. The original poster assumed internal bypassing. I think this means that's partly, but not full, true.
 
I thought it was best practice to always run the pump for a while after the cell has finished producing chlorine to flush out any trapped chlorine gas...... That would make the check valve unnecessary as well.

I currently have my pump timer set to come on 15 minutes before the SWG timer, and run for 15 minutes after the SWG timer shuts off.
 
domct203 said:
I thought it was best practice to always run the pump for a while after the cell has finished producing chlorine to flush out any trapped chlorine gas...... That would make the check valve unnecessary as well.

I currently have my pump timer set to come on 15 minutes before the SWG timer, and run for 15 minutes after the SWG timer shuts off.
Click to expand...
I am not aware of any automation system that does that. When the pump timer is off, power to both the pump and SWG goes off.
I still am not sure what kind of voodoo would have to happen for the flow to go backward when the pump turns off.
I suppose the only thing adding the check valve hurts is the $50 for the valve and some added headloss and flow reduction.
 
I totally disagree with that Raypak engineer and, unless he can back up his assertions with test platform data, he's essentially talking out of his rear-end. In a high velocity plumbing flow, there is absolutely no back diffusion that will occur...NONE, PERIOD. Anyone with half-a-cents worth of fluid dynamics can tell you that.

There is simply not enough chlorine gas generated to be of concern. Seriously, a check valve for an SWG is a NON-ISSUE.

If you do the calculations of flow rate and chlorine production rate you will find that, at minimum flow (which equals maximum chlorine gas concentration), the highest the FC ever gets is just a few ppm above current levels. There just simply isn't enough chlorine gas produced to be an issue. The pH is higher but high pH isn't an issue for metals.

Go ahead and install a check valve if you want but all you're doing is increasing the return-side head loss, that's it.
 
I wonder how to find out from the actual heater product designers if any of it was based on tests or was simply c.y.a. thinking. The guy I'd talked to last year had given the exampe of backwashing, but since my swg has the capacity to produce 1.5ish pounds of chlorine over 24 hrs that means at most 1 ounce in an hour or 1/60th of an ounce at any given moment that one might backwash. If the flow rate is, say, 60 gallons, that would only possibly spike the FC by 2 ppm for the instant before backwashing if you forgot to shut down the swg. It's entirely possible the product designers didnt have a full grasp on how SWGs work.

I don't really want to increase headloss but I do want to attempt to rule out any possibility that the copper shedding is coming from the exchanger via some process im iverlooking or dont understand, so I figured if I was going to install a check valve then I might as well put in the type with flow meter (to operate the vsp more finely) and have a bypass plumbed at the same time (to avoid any catastrophic pool shutdowns in winter now that I have the dome.) That way I'd get some utility from what might otherwise be a fool's errand ;)

Btw, DOM, even automation that isn't integrated with the swg fully can program the lag provided you connect the swg for on/off...via scheduling. That's what I do. I also mostly run the swg and heater at separate times, the exception being early evening bump ups in temp if needed.
 

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