Therm-X-Trol ST-12 Expansion Tank

A:  Yes it does. Thanks for the question. As a result I will update the listing to show this new feature. As a plumber let me add that although the insight cap is interesting, the biggest reason why installations fail or do not work correctly is not diaphragm failure. It is that most installations are not done correctly. Which is a shame. Water pressure is different in every home and post 911 DOT rules limit the extent to which these tanks can be pressurized and still be shipped over the road. Therefore as part of the installation process the air pressure in the tank must be balanced to the base line cold water pressure. When the tank is installed and the water in the heater is cold, you take a reading of the water pressure. Then you take the Insight indicator cap off exposing the shrader valve. Using a tire pressure gauge the pressure should be checked. Then either add or remove air to match the air pressure to the water pressure. This will "center" the diaphragm, allowing it the largest range of motion. Unfortunately this is very seldom done. Amtrol being a US manufacturer is allowed to ship there tanks with some pressure. But the imports typically arrive in the US un pressurized. Because most tanks are never commissioned properly, most are doing essentially nothing, but appeasing the inspector who wants to see one because of code. Every time I do a water heater change out, where there is a thermal expansion tank, I check it. Typically the gas chamber is virtually empty. If its an Amtrol it will be charged but very rarely balanced to the water pressure. Commissioning the tank properly will give it and the water heater a much longer life.

A:  3/4" Male National National Pipe Thread

A:  After a lot of research, YES, it can be installed at any angle. As the picture shows, I installed mine upside down because: 1. Weight of the tank when and if the internal rubber diaphragm fails and fills with water. Most of the tanks installed are hanging from a water line - big problem when the diaphragm fails. 2. Even when the diaphragm fails with it upside down, there will still remain an air pocket at the top. 3. checking & adding air to the tank is less of a problem with the tank in this position. Another suggestion: when charging the tank, first take pressure reading of your water line input. It's best to leave the pressure gauge on for a couple days to know the max pressure during any time. The tank should be charged to at least the max pressure before installed. That is why I installed a regulator, to ensure what the max pressure would be. Another point: If the tank is charged to the same pressure as you input, the diaphragm will be flexing a lot with any increase in pressure. I charged mine 10 lbs above input pressure because it reduces the ware-out effect of constantly flexing, and after all, the tank was put there to protect for over pressure and 10 lbs above input pressure is not a problem.

A:  The issue with expansion tanks being mounted on there side Is not related to any effect that orientation may have on there effectiveness. It has to do with the weight of the water they often contain. It will cause the expansion tank to break off; resulting in a flood. By installing them in a vertical position they are supported by the piping. This is why expansion tanks are often supported by strapping or brackets.

A:  The pressure in a thermal expansion tank must be set to match the cold water base line pressure when it is installed. This is part of the installation process. It is also the part that no one seems to ever do; including most plumbers. As such most thermal expansion tanks out there are doing much. In my home for example I have extremely high water pressure. I am at sea level and the water tower is way on a hill on the other side of town. So my water comes in at 110 PSI. I reduce it by way of a pressure reducing valve to 80 PSI. When I installed my thermal expansion tank I pumped in additional air so that the tank had 80 PSI in the air pocket. This put the diaphragm in the appropriate position. Now when the water is heated there is plenty go travel for the diaphragm to move. The system can get bigger as the water is heated and pressure does not rise. If I had low pressure I may have needed to take air out. Air is added or removed by way of the shrader valve. That is the fancy name for the valve that looks like the tap where you put air into a bicycle tire.