# Expansion Tank Connections



## Raleigh Plumbin (May 1, 2009)

We just failed an inspection from threading a 2.1 gallon expansion tank (304 SS nipple) into a copper female adapter. First time in 35 years. The inspector and says it needs dielectric protection or brass nipple/coupling. IPC says "Joints between stainless steel and different piping materials shall be made with a mechanical joint of the compression or mechanical sealing type or a dielectric fitting or a dielectric union conforming to ASSE 1079".

Here's my dilemma's. 
1. Copper and Brass are both at -.04 on the galvanic chart, BUT brass nipples and fittings contain zinc which is much more corrosive and prone to fail. Similar to the brass failures that have occurred in PEX fittings. Copper on the other had doesn't contain zinc and seems like the more logical choice. 
2. If I opt for the dielectric union, I'll be threading the S/S nipple into the galvanized side of the dielectric union which is a dissimilar metal. Galvanized is zinc covered carbon steel and therefore much weaker than the copper adapter again. 
Doesn't it make sense that copper to S/S is the best connection? Would love to here from an expert on the subject.


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## skoronesa (Oct 27, 2015)

Raleigh Plumbin said:


> We just failed an inspection from threading a 2.1 gallon expansion tank (304 SS nipple) into a copper female adapter. First time in 35 years. The inspector and says it needs dielectric protection or brass nipple/coupling. IPC says "Joints between stainless steel and different piping materials shall be made with a mechanical joint of the compression or mechanical sealing type or a dielectric fitting or a dielectric union conforming to ASSE 1079".
> 
> Here's my dilemma's.
> 1. Copper and Brass are both at -.04 on the galvanic chart, BUT brass nipples and fittings contain zinc which is much more corrosive and prone to fail. Similar to the brass failures that have occurred in PEX fittings. Copper on the other had doesn't contain zinc and seems like the more logical choice.
> ...





The rubber bladder will fail before anything rots if you use enough teflon tape regardless of your materials for pipe. Especially if you're hanging it upside down, it sounds like you are. 



The nipple should be on the bottom so any air stays in and if the bladder gets a hole it won't all piss out. Also, if there is a hole in the bladder than the air side will see less liquid.


I would say expansion tank into die union so galv steel on painted/galv steel, then sweat on the other half to your copper pipe.




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## skoronesa (Oct 27, 2015)

Also insulate the tank so the water won't cool and drop air into the wet side of the tank which could airlock it.




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## Debo22 (Feb 15, 2015)

Pipe it how the inspector wants it. When he signs off and leaves, switch it back.


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## Master Mark (Aug 14, 2009)

The inspector dont know what he is talking about....
the dialectric union has a very good chance of leaking due to the stress
at that joint... support it well if you actually have to do this to please the prick


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## Tango (Jan 13, 2018)

Raleigh Plumbin said:


> "Joints between stainless steel and different piping materials shall be made with a mechanical joint of the compression or mechanical sealing type or a dielectric fitting or a dielectric union conforming to ASSE 1079".


What does the ASSE 1079 say for it's definition?

As a contractor the plumbing code isn't enough as we are supposed to know other codes from who knows where if the plumbing code doesn't have what you are looking for.

I had that issue with hammer arestors and when I asked the pipes mechanics they sourced it from an american code trying to tell me to follow that. Great! It's almost as if they are making stuff up following another code from another country!


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## GAN (Jul 10, 2012)

I don't call this in my area and don't recall a State inspector calling it. If I had this brought up while I was still working, I would go with a brass female before I would ever consider a Di-electric union.

@Debo, your just mean. Let me know your area so I can warn your inspectors...…..:devil3:


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## ShtRnsdownhill (Jan 13, 2016)

Debo22 said:


> Pipe it how the inspector wants it. When he signs off and leaves, switch it back.



just give him a $20.00 for lunch and all is good....:vs_laugh::vs_laugh:


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## skoronesa (Oct 27, 2015)

GAN said:


> I don't call this in my area and don't recall a State inspector calling it. If I had this brought up while I was still working, I would go with a brass female before I would ever consider a Di-electric union.
> 
> @Debo, your just mean. Let me know your area so I can warn your inspectors...…..:devil3:





Mean or not this happens ALL THE TIME, and with things more "important" than an expansion tank. 



What bothers me about this is that the expansion tank will be a part of what he will be responsible for servicing under warranty so it would be in his best interest to do what he genuinely thinks will last longer. It's not like he is trying to cheap out using a stainless nipple instead of a dielectric, what's he saving? A dollar or two? I think the inspector should let RP do what he wants here.






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## ECH (Jul 27, 2018)

Raleigh Plumbin said:


> We just failed an inspection from threading a 2.1 gallon expansion tank (304 SS nipple) into a copper female adapter. First time in 35 years. The inspector and says it needs dielectric protection or brass nipple/coupling. IPC says "Joints between stainless steel and different piping materials shall be made with a mechanical joint of the compression or mechanical sealing type or a dielectric fitting or a dielectric union conforming to ASSE 1079".
> 
> Here's my dilemma's.
> 1. Copper and Brass are both at -.04 on the galvanic chart, BUT brass nipples and fittings contain zinc which is much more corrosive and prone to fail. Similar to the brass failures that have occurred in PEX fittings. Copper on the other had doesn't contain zinc and seems like the more logical choice.
> ...


We service Durham, Raleigh, Chapel Hill area and all of our expansion tanks are hung on brass drop ear 90s, or copper females/brass couplings, or sideways with band iron to a wall (when using pex) I don't love the band iron method cause I think it looks sloppy, but that's just me......

This inspection correction is not one I have ever heard of, the most we ever hear of is not supporting it correctly. The "spirit" of the code (as we understand it) is to keep the stress of the weight of the tank off the fittings and pipe.

I have passed many inspections with the tank mounted vertically, nipple pointed straight down, straight shot to the heater nipple, this minimizes any stress on fittings and pipe, and looks nice in my opinion. And several passes using a drop ear to splice into the cold line in the crawl space if the heater location is too cramped, I don't love this one either, because then the tank is nipple up, and the weight of the water is contributing to bladder failure, but technically, it is not a reason for inspection failure. I also will sometimes build a shelf out of 2 x 4s, so I can use a drop ear, but with tank nipple down, if there is room near the heater location.

Never once had a problem with metals. In this area, those dielectric unions get plugged up quick, I hate them.

I would call the inspector and "fight" that one, respectfully of course.

Last month I had an inspector try to make me put a pan under a tankless in a sealed crawl space. I called bull, code states that is for tank style heaters, and besides that, replacement installs do not require drain piping from the pan to outside anyway.

So I asked the guy why would he subject the customer to more visits and me to more cost, if any leakage is just going to dump on the crawl floor anyway?

He agreed, and passed it.


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## jakewilcox (Sep 3, 2019)

The inspector doesn’t know what he’s talking about. In my area that’s not uncommon. It’s going to be a lot easier just to do what he wants and not fight with him. If you are going to challenge him make sure you get your ducks in a row code wise. That said, it’s going to be a hell of a lot easier to just go with the flow.

There’s a good percentage of the members on here that would probably agree with me that I’m good plumber knows more than almost any given inspector about code.

I’m sorry I don’t have a better answer for you.


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## rwh (Dec 17, 2014)

This makes me glad we aren't required to use expansion tanks on open systems here.


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## skoronesa (Oct 27, 2015)

rwh said:


> This makes me glad we aren't required to use expansion tanks on open systems here.





if it's an open system why would you need an expansion tank?




















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## rwh (Dec 17, 2014)

Apparently its code to have expansion tanks in homes in some places.

QUOTE=skoronesa;1223618]


rwh said:


> This makes me glad we aren't required to use expansion tanks on open systems here.





if it's an open system why would you need an expansion tank?




















.[/QUOTE]


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## skoronesa (Oct 27, 2015)

rwh said:


> Apparently its code to have expansion tanks in homes in some places.





When he said it was an open system I thought he meant an atmospherically vented steam heating system.




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I have never heard the term "open system" being used to describe a domestic water system. I see now that he meant a domestic system with no checks. I understand why they might want an expansion tank if you're hooked to city water, could be pressure spikes. 



Does a PRV act like a check valve? Maybe that's there reasoning.











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## jakewilcox (Sep 3, 2019)

A PRV is not back flow prevention by any means, but by definition water can not flow from low pressure to high pressure. So, yeah, they should be treated as a “closed system” or a checked system. 

Edit: I realized I might not be being clear. 
In my area, we install an expansion tank on any system with a PRV. However, (harkens to my comment above) almost NO inspector will catch that one.


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## Fast fry (May 19, 2012)

We have made points to carrying paint and other stupid stuff to manipulate morons like this inspector. I pretty much heave had to write a book on these little tricks . Pretty much have something for everithing


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## panther (Oct 27, 2010)

I got called on this for a small commercial job I did. Expansion tank to 3/4" copper female adapter. It was located in the ceiling without a ton of extra room. Normally, I use brass tee, 90, 6" nipple and short brass nipple out of the top of the tee.


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## sparky (Jan 8, 2014)

ECH said:


> We service Durham, Raleigh, Chapel Hill area and all of our expansion tanks are hung on brass drop ear 90s, or copper females/brass couplings, or sideways with band iron to a wall (when using pex) I don't love the band iron method cause I think it looks sloppy, but that's just me......
> 
> This inspection correction is not one I have ever heard of, the most we ever hear of is not supporting it correctly. The "spirit" of the code (as we understand it) is to keep the stress of the weight of the tank off the fittings and pipe.
> 
> ...


That bladder is gonna fail no matter what or how you place it,about two yrs all you gonna get out of a properly sized and aired up expansion tank


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## ShtRnsdownhill (Jan 13, 2016)

sparky said:


> That bladder is gonna fail no matter what or how you place it,about two yrs all you gonna get out of a properly sized and aired up expansion tank


I have to disagree with you on that, if your expansion tanks are failing after 2 years you have other problems...I have installed expansion tanks on both closed heating systems and potable water systems still going strong for over 10 years, including in my own houses...


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## Plumbus (Aug 4, 2008)

ShtRnsdownhill said:


> just give him a $20.00 for lunch and all is good....:vs_laugh::vs_laugh:


 :vs_laugh::vs_laugh::vs_laugh:


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## jim285pro (Sep 3, 2020)

While you guys are on expansion tanks, do you all set the tank air pressure equal to or slightly more than the water PSI? or do you leave it at the factory precharge? Curious what others do.


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## skoronesa (Oct 27, 2015)

jim285pro said:


> While you guys are on expansion tanks, do you all set the tank air pressure equal to or slightly more than the water PSI? or do you leave it at the factory precharge? Curious what others do.




You almost never leave it at the factory precharge. The exception being it happens to match the pressure you require. *It's also best to install the expansion tank per the manufacturers instructions.*

For a well pump system you set the air pressure to be equal to or slightly less than (-1 or 2psi) the cut-in pressure of the pressure switch. 

With city water you would set the air pressure to be slightly less than (5psi) the pressure regulator output or the incoming pressure if there is no regulator present. If there is a regulator the expansion tank should go on the house side of the regulator. 

The idea being that with no regulator the tank will absorb pressure spikes when a city pump kicks on. When there is a prv present the tank absorbs the pressure increase when the hot water heater goes from high demand (colder) to low demand (hotter, water expands, pressure increases).

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## jim285pro (Sep 3, 2020)

Seems like if the air pressure is lower than the water PSI The expansion tank has little to no room for expansion. Wouldn’t the higher water pressure fill the ballon to capacity? Would Newton’s law not apply here? I was always taught slightly above. 5psi range. I’ve seen others never touch the Schrader and not have problems. Maybe I’m not grasping the tank construction fully. Mainly in regards to thermal expansion.


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## skoronesa (Oct 27, 2015)

jim285pro said:


> *Seems like if the air pressure is lower than the water PSI The expansion tank has little to no room for expansion. *Wouldn’t the higher water pressure fill the ballon to capacity? Would Newton’s law not apply here? I was always taught slightly above. 5psi range. *I’ve seen others never touch the Schrader and not have problems.* Maybe I’m not grasping the tank construction fully. Mainly in regards to thermal expansion.


1 or 2psi lower is miniscule compared to the 20-30psi swing that the air pressure will see when the system is active. 1 or 2psi has almost no effect on the total room for expansion.

And of course they have problems, eventually all tanks have problems and need to be replaced. What we're trying to do is increase the time the tank lasts. Having a proper air charge is important for that reason, not just because the system may not behave ideally.

There is a greater risk of the bladder getting harmed if the air pressure is higher than the water pressure. This causes the bladder to get forced into the opening in the bottom of the tank. Aside from the fact that the opening is small, possibly sharp, and would abrade the bladder by itself, there is also usually a build up of sediment in the bottom of the tank and you want to avoid the bladder being pressed into this.

On the other hand if the air pressure is slightly lower the bladder is just stretched a little in the direction it is intended to stretch. Ideally the air pressure would exactly match the static or cut-in pressure. But since the town water and the pressure switch on your well are never exact we "air" on the side of caution and go with a slightly lower pressure.





Thermal expansion tanks are pretty easy to get right and I bet you could just leave them at the factory precharge the majority of the time. I believe amtrol brand comes with a 55psi precharge. The air charge should be a little lower than the lowest pressure you expect the system to see. If you're installing an expansion tank on city water you likely have a prv which are often preset for 55-75psi. So a 55psi air charge would be fine. All you're trying to stop is water hammer and the blow-off that would occur from the cold water heating up and expanding which isn't much. That's why they are only the size of basketballs.

With well tanks you need to be a little more precise as improper pressure can cause pressure surges and drop outs.

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## czplumbing (Nov 24, 2014)

I leave them factory


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## jc2002 (Aug 18, 2013)

In St. Louis county you have to have them in The City of St. Louis you don't the difference is the one has a meter the other doesn't. BUT they have to be set to static pressure and have to use a dielectric union, a brass cuppling or we use the bronze propress union. Also the biggest problem with them isn't that they fail its they are not checked yearly like they are supposed to be just like dielectric unions


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