How to remove pressure from therm-x-trol to replace it

SOURCE: therm-x-trol st-12 leaking

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

SOURCE: I am loosing water pressure in my shower so I

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

SOURCE: I have an ST-5 Therm-X-Trol

Hi,
You are correct... the tank should not be full... usually the problem is that the bladder inside breaks and then the air escapes....or more accurately is disolved into the water.

The ST tanks are usually used for expansion on domestic water systems to make up for hot water heater expansion. If there is a check valve at the entry point then the tank is needed to allow for water expansion upon heating in the hot water heater. Therefore the bladder pressure is usually about 100 psi +or- depending on the setup. the main thing is that the pressure is lower then the relief valve stting usualy about 125 psi.

The tank can be bought online or at many big box stores and it is easy to replace.
Simply shut off the wwater...isolate as much as possible and then relieve the pressure at the closest point to the tank...
Then just unscrew the tank... dope or tape with thread sealant, the threads of the new one and screw in back into the fitting...

There you are back in business again...

heatman101