Thermal Exchange and Fabricated Products
Can a Taco bladder or diaphragm-style expansion tank be installed in the horizontal position?
The Taco bladder type CA tanks and CX tanks can be installed in the vertical or horizontal position. The NSF/ANSI 61-G certified PAX tank can only be installed vertically while the non NSF/ANSI 61-G certified PAX tank can be installed horizontally or vertically. The CBX tank is limited to vertical installation. If the tank is installed in the horizontal position, Taco’s U-bolt saddle set or cradle type saddle set will likely be required. Remember to check local code requirements to insure proper tank installation and mounting. When installing Taco CA model expansion tanks in the horizontal position it is important to ensure that the tank is installed with the system connection pointing towards the floor to allow for easier tank and/or bladder maintenance.
How do I check the air charge pressure in a Captive Air Expansion Tank?
Isolate the tank from the system and break the connection, so that any fluid inside can be allowed to escape. The true air charge can’t be determined until all the fluid is removed. The air charge will equal the system pressure until the fluid is removed from the bag. If the air charge is higher than the system pressure, there should be no water in the bag and the pressure reading should be the true air pressure reading.
Remember, the water is inside the bag and the air is between the inside of the steel shell and the outside of the bag. If the tank does not have an air charge, air should be introduced which will squeeze any remaining water out of the bag. When the fluid stops coming out, you can now accurately determine and adjust the air charge pressure within the tank.
Attachment: Expansion Tank Service Instructions
Should I connect a drain to the bottom of my Captive Air Expansion Tank?
No, doing so could cause an air leak at each pipe joint, packing gland and valve seal. Remember that the water is inside the bag. Unlike the old, plain-steel type tanks, the CA tank doesn’t need to be drained.
What is the correct air charge pressure for my Captive Air Expansion Tank?
The air charge pressure should be equal to either the system fill pressure or the PRV setting if the tank is at the same elevation as the PRV. If the tank is located at any other elevation in the system, the charge pressure in the tank should be the cold pressure of the system at that elevation.
Does the Taco Buffer tank comply with any codes?
ASME Code Section VIII Division 1, Max Design Pressure and Temperature: 125 @ 375F. Registered with the National Board of Pressure Vessel Manufacturers.
Refer to the Submittal Data Sheets under the documents tab on the following product pages:
What is the purpose of the screen in the system connection on top of the expansion tank?
The screen is there to protect the bag from being forced out of the connection port when installed in a high pressure system.
Why do I need an expansion tank in my chilled water system?
A chilled water system is filled with water at a temperature between 50 and 60°F. When the chiller is turned on, the temperature of the water drops to 45°F. When the water contracts, the system pressure drops, and the fill valve allows more water to enter the system to maintain the system pressure.
If the chiller shuts down and the water in the system warms up to room temperature, the rise in temperature from 45° to ambient will cause the water in the system to expand. Without an expansion tank, the relief-valve would blow. The tank can be smaller than the one used in a hot water system, because the temperature is rising from 45°F to ambient, instead of from ambient to 200°F.
What information is required to order a replacement tube bundle for my shell and tube heat exchanger?
In order to purchase the correct replacement parts for a heat exchanger, including tube bundles, it is necessary to provide the heat exchanger’s serial number. The serial number is stamped onto the heat exchanger three times in three different locations, as illustrated in the attached diagram. Because piping arrangements and the addition of insulation to the heat exchanger may make locating the serial number difficult, any one of these three will do (they’re all the same). However, if possible, the serial number off of the tube plate is preferable.
Attachment: Heat Exchanger Serial Number Locations