# expansion tank



## plumb nutz (Jan 28, 2011)

Expansion tank failure. Just to make it a little better, this tank was for a 6 gallon heater...


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## Redwood (Sep 8, 2008)

plumb nutz said:


> Expansion tank failure. Just to make it a little better, this tank was for a 6 gallon heater...


A 4.5 Gallon Expansion Tank on a 6 gallon water heater? :laughing:

That's some funny stuff right there....


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## mpvan85 (Jun 8, 2011)

Can someone explain to me what had happend here please? This looks very interesting....


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## Widdershins (Feb 5, 2011)

mpvan85 said:


> Can someone explain to me what had happend here please? This looks very interesting....


Judging by the number of threads that still have teflon tape on them, I'd say the leaking connection rusted out the top of the expansion tank.


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## mpvan85 (Jun 8, 2011)

ohhhhhhhhh IC

Thanks


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## Will (Jun 6, 2010)

That's way I use Thermal Expansion Valves, not tanks.


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## Cal (Jun 17, 2008)

http://www.watts.com/pages/_products_details.asp?pid=564

Me too !


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## cityplumbing (Jun 12, 2010)

Will said:


> That's way I use Thermal Expansion Valves, not tanks.


Never heard of a thermal expansion valve.. What is it and how does it work?


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## Redwood (Sep 8, 2008)

I'm not a big fan at all of using a relief valve for thermal expansion...

It's a good way for a customer to discover a problem exists with an increase in water pressure or, a failed PRV by reading a huge quarterly water bill.... :whistling2:

A properly installed and precharged thermal expansion tank actually does usually have a decent service life....

I'm convinced that many premature failures of expansion tanks are caused by installers that fail to match the precharge to the water pressure...


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## cityplumbing (Jun 12, 2010)

I would think that a releif valve is a safety only not a means to control thermal expansion in a system.. I've seen techs replace diaphram type expansion tanks thinking they failed when they have just lost there charge.:thumbsup:


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## GREENPLUM (Jul 27, 2008)

When I got started plumbing they would hang exp tanks on CPVC and makeshift some kind of support.

Who would have thought that wouldnt hold up?


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## Redwood (Sep 8, 2008)

cityplumbing said:


> I would think that a releif valve is a safety only not a means to control thermal expansion in a system.. I've seen techs replace diaphram type expansion tanks thinking they failed when they have just lost there charge.:thumbsup:


It they lost their charge they probably had failed....


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## Tommy plumber (Feb 19, 2010)

LPG said:


> you must of read that on google...cause we all know your not a real plumber....chump..... you sit online all day making dumb posts to help your ego...fuk you b!tch


 




Now now, sub-standard intelligence is no reason to resort to profanity. We have standards here and rules.


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## plumb nutz (Jan 28, 2011)

So after further examining the tank I'm believing that the tank was:
1. Oversized for the application
2. Improper charge as this came from the 8th floor of an office building with a booster pump
3. The failure was from inside the tank as the male adapter was firmly set and not leaking


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## BROOKLYN\PLUMB (May 21, 2010)

A relief valve can not be used instead of expansions tanks they are not doing the same thing and besides the water bill your going to have premature equipment failure and you will void your warranties I can't believe this was even put out there as an option


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## TX MECH PLUMBER (May 27, 2011)

Around here we don't use tanks unless you have a backflow preventer installed


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## Greenguy (Jan 22, 2011)

Out here and in vancouver only right now they require thermal expansion valves on all new hot water tanks. That's direct from an inspector I talked to on Thursday. 

That said alot of guys here take the tank out of the box and install them with out adjusting the charge on them.


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## gitnerdun (Nov 5, 2008)

125lb relief valve here. It is usually outside at the backflow device. Although after the water heater shut-off is better.

I don't quite understand why so many like the tank, you have to adjust the precharge, you can't tell by looking at it if it has failed or not, and it has a limited capacity. Not to mention HOs have no clue what it is or how it works or if it is working and when it leaks they just remove and plug it.

What happens if the t-stat stays on, where does that expanded water go? It has to go somewhere and that little tank ain't gonna hold it all.


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## plbgbiz (Aug 27, 2010)

Redwood said:


> A 4.5 Gallon Expansion Tank on a 6 gallon water heater?....


May not be as far off from needed as we think. It has to handle thermal expansion for the whole hot water system, not just the heater. According to the IPC commentary, when heated 100 degrees Fahrenheit, 40 gallons of water becomes 41 gallons.

That is, *IF* the 6 gallon water heater were connected to a few thousand feet of 1/2" pipe. :laughing:


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## cityplumbing (Jun 12, 2010)

Redwood said:


> It they lost their charge they probably had failed....


You never know a DIY homeowner could could have let air out or it could have a failed shredder pin. Either way it's more cost affective to change it out after properly diagnosing the system.


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## plbgbiz (Aug 27, 2010)

BROOKLYN\PLUMB said:


> A relief valve can not be used instead of expansions tanks they are not doing the same thing and besides the water bill your going to have premature equipment failure and you will void your warranties I can't believe this was even put out there as an option


The IPC references the use of a device for controlling pressure as a result of thermal expansion. The commentary states this can be accomplished with an expansion tank or a thermal relief valve. There is a difference between a standard pressure relief valve, and a thermal expansion relief valve.


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## BROOKLYN\PLUMB (May 21, 2010)

You know what I'm thinking in terms of a hot water boiler because we don't use any thermal expansion devices on water heaters so I see this valve says exclusively hwh so my earlier view is wrong as a hwh is not a closed system like a hot water boiler and the effects of losing water is the same as opening a tap (not going to cause premature failure) however I still don't like it


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## plbgbiz (Aug 27, 2010)

Dad did a lot of boiler work but it is certainly not my strongest suit.

I agree the valve discharge is a negative. Sometimes we don't have anymore room for an expansion tank in an old closet than you have for gas meters on the sidewalk.

Are there failure or function problems with the thermal expansion valves?


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## BROOKLYN\PLUMB (May 21, 2010)

I hear you on the space


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## Greenguy (Jan 22, 2011)

plbgbiz said:


> Are there failure or function problems with the thermal expansion valves?


Besides the fact you have to Tie the valve into a drain you get any gunk in the seat and it's pissing water continuously, I know guys that use them as trap primers because they are constantly letting out small amounts of water.


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## gitnerdun (Nov 5, 2008)

plbgbiz said:


> Are there failure or function problems with the thermal expansion valves?


There were problems when a 75lb valve was code, but now with a 125lb valve it's good unless there is a problem, then it will blow off a little. But leak a little is their job afterall. We put them outside in sight here in FL so if they leak someone sees it. No freezes to worry about either.


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## cityplumbing (Jun 12, 2010)

Are we talking about a temperature pressure relief valve here? That comes with a water heater!


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## gitnerdun (Nov 5, 2008)

one of these, not a tp valve just pressure. They usually just drip a little then close after pressure drops.


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## cityplumbing (Jun 12, 2010)

We use these as a requirement by one of the building departments in my area when were installing new water service lines but had an issue with a customer that had a gas heater and a check valve installed at the meter it created a closed system which caused the pressure to increase and spill everytime there water heater kicked on. Its funny because it didn't happen to another home I did on the same block that had an electric water heater.


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## plbgbiz (Aug 27, 2010)

cityplumbing said:


> Are we talking about a temperature pressure relief valve here? That comes with a water heater!





gitnerdun said:


>





cityplumbing said:


>


No to all of the above. I'm talking about one of these...


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## cityplumbing (Jun 12, 2010)

How much does that puppy cost??


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## cityplumbing (Jun 12, 2010)

cityplumbing said:


> How much does that puppy cost??


*Product Description*

Apollo Valves 78304RV Water Heater Shutoff/Thermal Expansion Control Valve

Thermal Expansion Control Valve, Size 3/4 In, Sweat Connection, Max Pressure 125 PSI WOG, Full Port, Material of Construction Bronze, Seats RPTFE, Seals RPTFE, Ball Material Chrome Plated, Stem Material Brass, Stem Blowout Proof, Handle T, Temp. Range 33 To 210 F, Overall Length 4 In., Standards Meets IAPMO, CSA B125.1, B125.3


Price: $46.45 
*I got it!!*


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