Thermal Expansion Bladder Tanks

Bladder tanks are required in a closed loop heating or chilled water HVAC system to absorb the expanding fluid and limit the pressure within a heating or cooling system. A properly sized expansion or compression tank will accommodate the expansion of the system fluid during the heating or cooling cycle without allowing the system to exceed the critical pressure limits of the system.

The expansion or compression tank uses compressed air to maintain system pressures by accepting and expelling the changing volume of water as it heats and cools. Some tank designs incorporate a diaphragm or bladder to isolate the expanded water from the pressure controlling air cushion.

As water is expanded, it is contained in the bladder preventing tank corrosion and water logging potentials. The pressure controlling air cushion is pre-charged at the factory and can be adjusted in the field to meet critical system requirements. This design and operation of this style of expansion tank allows the designer/specifying engineer to reduce tank sizes up to 80%.

Bladder tanks have a totally replaceable bladder. This tank must be equipped with large service openings and also allow the bladder to be replaced without having to remove the tank from its mounting.

TXA Series (ASME)

The TXA’s are the industries broadest line of bladder style tanks.

  • Heavy-duty replaceable butyl bladder
  • Sizes range from 10 to 528 gallons
  • Working pressures of 150 psi (std), 200 and 250 psi

The TXA bladder style tanks boast many advantages over other style thermal expansion tanks.

  • Can be easily replaced in the field
  • Free standing models have a system connection at the bottom of the tank
  • Designed to prevent any harmful build-up of dirt, grit or system contaminants
  • Easy draining to assist in establishing proper air charge

TX Series (Non-ASME)


The TX Series tanks are designed for use in low pressure residential systems and in light commercial systems where ASME construction is not required.

  • Heavy-duty replaceable butyl bladder
  • Sizes range from 2 to 80 gallons
  • Factory pre-charged to 40 psig (field adjustable)
  • Rated for 200°F operation