Expansion Tank Tee

[go_hercules]

I need to install an expansion tank over an existing water heater in a pretty confined space. Regarding plumbing it in, the supply ball valve out of the wall has threads that connect to a corrugated copper hose (I believe a BrassCraft or the like). If I want to put a tee right off the ball valve, what threads would the tee have? I think they show the hoses as FIPS but is this the same as NPT? I would like to put the tee at the ball valve with the other two ports going to the heater and the tank with similar corrugated copper lines. (see next post, I added an image).

 

[go_hercules]

Could not figure out how to add the image in my post above, but here is what I am thinking.

 

[Sponsor]

 

[Reach4]

I need to install an expansion tank over an existing water heater in a pretty confined space. Regarding plumbing it in, the supply ball valve out of the wall has threads that connect to a corrugated copper hose (I believe a BrassCraft or the like). If I want to put a tee right off the ball valve, what threads would the tee have? I think they show the hoses as FIPS but is this the same as NPT? I would like to put the tee at the ball valve with the other two ports going to the heater and the tank with similar corrugated copper lines. (see next post, I added an image).

FIPS is usually the same as NPT when talking about threads.

However you put an expansion tank, it needs to be supported if it is not straight upright or upside down. An expansion tank does not have to go next to the WH. I am not a plumber, but I think your method would be fine if you support the tank well.

To add a add an image during an edit, click More Options.

 

[go_hercules]

If not by the water heater, where else are these tanks mounted??

 

[Reach4]

http://www.amtrol.com/media/documents/thermxtrol/9015087_06_16_Thermal_Expansion_Tank_IO_.pdf says

Install the expansion tank on the cold water supply line to the water
heater at a point between the water heater and backflow preventer or
other one-way device​

The backflow preventer is probably at the water meter.

Clearly the thermal expansion tank should not be separated from the WH by a valve that would be closed while the WH is operating. To me, that would not include the shutoff for the WH water, since that would never be closed while the WH is operating.

 

[Jadnashua]

To meet the requirement, there should not be any valve of any type between the ET and the WH. Will it work, yes, as long as that valve is never closed. That's pretty near impossible to do with a check valve (assuming it's working properly), and Murphy's law says someone will close that valve. The codes are written to help prevent Murphy's law from being a factor. What you do in your house, if it's not being inspected, is your problem. The codes are written to account for the system's life, which may continue after you're gone. Say you're doing some service work on the hot water line...only shut off the supply to the WH, but then the WH fires up...the ET won't be able to do its job because it is isolated from the source of the expanding water.

 

[Reach4]

"the requirement"? It sounds as if you are implying that UPC or IPC has a rule supporting your claim.

 

[go_hercules]

Original poster back here - besides above the water heater, I also have a utility room off the garage that has a sink and plenty of room. I was thinking about teeing off of the sink cold water supply to put the expansion tank. Any problem with that?

 

[Reach4]

No problem IMO as long as that only has the WH shutoff valve in the way.

Note if you run new piping to the tank, the size of the line is not important. So if 3/8 PEX was handy for some reason, you could use that. Of course no problem using bigger connections.

 

[go_hercules]

Original poster again - saw an installation online that looks like I might be able to copy and squeeze in. Would the weight of a 2 gallon tank be too much to hang off the pipe like that?

 

[Cacher_Chick]

You have to remember that the tank is only good for a few years, and when is fails it will fill with water and will be quite heavy. Anytime such a tank is installed, the mounting needs to be able to accommodate the weight of the tank when it is full of water.

 

[Jadnashua]

If you look at the installation diagrams of the ET's that I've looked at, all of them show the ET installed on the cold line with no valves between it and the WH tank itself. Many also want the ET installed at least 18" away from the WH to help limit the amount of heat it is exposed to. All of them also will void any warranty if the incoming pressure exceeds 80psi (the max allowed in a residential setting). Code generally requires the appliances and devices to be installed per the manufacturer's instructions if it doesn't specifically state a method. IOW, the code may or may not specifically state, but they do call for it to be installed as directed by the manufacturer. Lots of things will 'work' if you are careful, but there is only one way to ensure someone doesn't do something stupid or forgetful, and that's to not have a valve between the WH and the ET.

 

[go_hercules]

Good info, I appreciate it. I know the tank goes on the cold side but I was trying to think through the process of expansion. So cold water enters the tank and gets heated. With faucets closed, the water can't expand so pressure builds. Got that, but what I don't get is whether the pressure builds up in the hot AND cold water lines. In other words, does the hot water in the tank push "forward" into the hot water lines, and also push "backward" back into the cold water lines? In other words, without an expansion tank, would you see a rise in pressure at both the hot and cold water faucets?

 

[Reach4]

In other words, does the hot water in the tank push "forward" into the hot water lines, and also push "backward" back into the cold water lines? In other words, without an expansion tank, would you see a rise in pressure at both the hot and cold water faucets?

Yes. Yes.

 

[go_hercules]

Thank you.

 

[Reach4]

All of them also will void any warranty if the incoming pressure exceeds 80psi (the max allowed in a residential setting).

You are still making stuff up.

 

[Jadnashua]

You are still making stuff up.

Read the warning on the top of the first page.
"Do not exceed 80psi (5.5 bar) air charge. Air charge pressure exceeding 80psi (5.5 bar) could become hazardous and will void any and all warranties, either written or implied."

http://media.wattswater.com/2915054.pdf

Calling someone a liar when it is true is not only rude, but shows ignorance and disrespect.

 

[Reach4]

Read the warning on the top of the first page.
"Do not exceed 80psi (5.5 bar) air charge. Air charge pressure exceeding 80psi (5.5 bar) could become hazardous and will void any and all warranties, either written or implied."

http://media.wattswater.com/2915054.pdf

Calling someone a liar when it is true is not only rude, but shows ignorance and disrespect.

Had I called somebody a liar when it is true would show disrespect, but hardly ignorance. Calling somebody a liar when that is untrue could be ignorance. However I did not call you a liar. It is possible that you believed what you wrote. Now sometimes/often I am ignorant. I try to make that temporary, as opposed to willful.

Giving an example of one instance to prove a claim that "All of them also will void any warranty if the incoming pressure exceeds 80psi (the max allowed in a residential setting)" is not informed. The only link on this thread before your Watts link is the instructions for Therm-X-Trol, certainly among the best expansion tanks, and probably the best. They do not make the exclusion that you claimed all do. [sarcasm]You would not claim that somebody in Minnesota was violating a law because of doing something that was not allowed in California, would you? [/sarcasm]

Edit: I guess I could have instead used the term invented or dreamed up. It could have come from your subconscious. I actually think it was incorrect opinion presented as authoritative fact.

 

[Jadnashua]

Plumbing code sets 80psi as the maximum for a residential situation. While things are tested to higher values to provide a safety margin, that does not mean that they should ever see that higher value. Devices sold are expected to be installed and used within the code...that's 80psi maximum. Anything higher is out of bounds, whether specifically stated or not on a product data sheet.

You buy a rope rated for 500#, you don't expect it to snap at 501#, but technically it could...that's why they build safety margins into products. Flaunting the design limits may eventually come back to bite you in the a.. Ignoring them and recommending others to do it is irresponsible.

 

[Reach4]

Plumbing code sets 80psi as the maximum for a residential situation. While things are tested to higher values to provide a safety margin, that does not mean that they should ever see that higher value. Devices sold are expected to be installed and used within the code...that's 80psi maximum. Anything higher is out of bounds, whether specifically stated or not on a product data sheet.

You buy a rope rated for 500#, you don't expect it to snap at 501#, but technically it could...that's why they build safety margins into products. Flaunting the design limits may eventually come back to bite you in the a.. Ignoring them and recommending others to do it is irresponsible.

Laying a smoke screen? Precharge? Rope? Straw man. Did you lose track of what was under discussion: placement of a thermal expansion tank.

But since you brought up your "80psi as the maximum for a residential situation", I will point out that the Therm-X-Trol says "Residential sizing based on: 40°F incoming water temperature; 150 psi T&P safety relief valve; Pre-charge equal to static supply pressure."