in-ground sprinklers

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rh71

No Lifer
Aug 28, 2001
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anyone familiar with in-ground sprinkler systems? They're saying with in-ground systems, they require a special type of extrol tank (ST-5)? It's attached to my hot water tank. Is there any reason why I can't use a typical extrol tank in its place? The ST-5 is done-for and need a replacement as it's affecting my hot water tank. If I have to stay with ST-5, I won't be covered under the current warranty, thus the reason I'm asking.

tanks
 

dabuddha

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Apr 10, 2000
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We installed an underground sprinkler system in our house in Texas and never heard of a extrol tank. Not sure why you would need one.
 

Demon-Xanth

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Feb 15, 2000
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Doing a search, it looks like they're usually used with radiant heating systems to absorb the pressure from the expansion and contraction due to heat. Searching for extrol tank sprinkler on google, this thread comes up as hit #2.
 

Tobolo

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Aug 17, 2005
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We are required to have them in GA due to code restrictions, but I've never heard of it being required for irrigation systems. Of course since everyone here has them....
 

rh71

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re: google... g'damn they're fast

ST-5 description: http://www.amazon.com/Amtrol-T...1JHHO/ref=pd_rhf_p_t_1

We have a requirement for backflow prevention devices but I thought that was somewhere outside. I suppose this tank works in conjunction with it. I really can't make heads or tails of the description in terms of necessity though... thermal expansion because of backflow devices? Exactly how dangerous can this get.. if I use a regular expansion tank...
 

iGas

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Feb 7, 2009
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Expansion tank generally are use on hot water boiler systems.

House hold boiler system is set default by the boiler feed (default 12-15 psi pressure regulator) and it allow water to flow into the system (water makeup) if pressure drop below the default setting.

Expansion tank is there to keep the pressure regulated below default setting at 30 PSI when the water reach 140~160 F (max 180 F, water expand about 4% from street temp to 180 F). If expansion tank is water logged then the pressure would exceed the design pressure of system, thus trigger the pressure relief valve (default 30 psi) to evacuate water pressure.

No you don't need an "expansion tank" for your in ground sprinkler, however you may need a "pressure tank" if you are using a pump to pressurize your watering system.

Depends on the jurisdiction & your sprinkler system needs/design; you may need a PVB (pressure vacuum breaker), or DCVA (double check valve assembly), or RPBA (reduced pressure backflow assembly).
 

iGas

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Exactly how dangerous can this get.. if I use a regular expansion tank...
Look up Mythbuster video on hotwater tank experiment.

Water expand 900 times it volume when change phase to steam. If every failsafe in your boiler system malfunctions and doesn't shut the system off, then a possible catastrophe may occurred.



 
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