Question about Amtrol ST-12-C THERM-X-TROL ASME Expansion Tank, 5 Gallon

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Therm-x-trol st-12 leaking

I've noticed this problem in the last few days. It is about 15 years old, house was built in 1993 and I doubt it has been replaced. It is very close, less than a fingers width from an old copper pipe. However, the pipe seems dry and dusty on the outside. How can I tell if it is the therm-x-trol st-12 leaking from the side, again the top seems dry and dusty as well or the pipe? Thanks for your future help.

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Never seen one leak other from the seam or the top or bottom.

Posted on Mar 14, 2009


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1 Answer

Water pressure decreases as the water runs

Probably a clog in galvanized pipe.
Expansion tank is not whole-house pressure regulating tank. It is localized protection for plumbing exposed to high pressure caused by very hot water.
If you house has pressure regulating valve, then that can be a cause.
For low water pressure in household, the following link might help:

Aug 07, 2011 | Amtrol ST-12-C THERM-X-TROL ASME Expansion...

1 Answer

The relief valve coming out of my hw heater occasionally has a steady drip of hot water after the heater has been running. Drips accumulate in a bucket maybe a gallon/ week. Gas company rep (here for a...

The exspansion tank is more than likly the problem. The temperature/presure valve may also be the problem. Replace both. To replace the exspansion tank turn off the supply water coming into the water heater. Open the relief valve and purge the presure off the tank. drain the water heater slightly below the temperarture/presure valve to replace. The exspansion tanks screws off. Use new teflon taope on the threads when replacing both the exspansion tank and the T&P valve. This work can be compleated by the homwowner with some mecanical inclination.

Jan 23, 2011 | Amtrol ST-5-C THERM-X-TROL ASME Expansion...

1 Answer

I am loosing water pressure in my shower so I checked pressure at my ST-12 Therm-X-Trol tank hoping it would be 40 but water comes out of the test point and if you tap the tank it feels like it is full of...

you are correct....the rubber bladder inside the tank has leaked by and filled the expansion tank. it will need to be replaced and you also may find boiler or water heater relief valves may blow off until its replaced

Oct 21, 2010 | Amtrol ST-5-C THERM-X-TROL ASME Expansion...

2 Answers

Short buzzing noise every few seconds from hotwater tank

it maybe that there is a small leak at the connection.try to remove the tank and put teflon tape on the connection.this may fix the problem.if this does not fix the problem,it may be possable that the amtrol has a pin hole in it.this may hve to be replaced.good luck with your project

Sep 29, 2009 | Amtrol ST-5-C THERM-X-TROL ASME Expansion...

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