27.7 Gal. Hydronic Heating Expansion Tank

Zilmet ZHT105 – 27.7 Gallon Expansion Tank for Closed-Loop Hydronic Heating Systems

The Zilmet ZHT105 is a 27.7-gallon diaphragm-type expansion tank designed for sealed hydronic heating systems. It accommodates thermal expansion by maintaining pressure balance within the system, helping to prevent over-pressurization, component fatigue, and premature equipment failure. This model is appropriate for larger residential and light commercial installations.

Constructed from welded carbon steel with an epoxy-polyester coated exterior, the tank includes a seamless synthetic rubber diaphragm that separates the air and water chambers. This configuration ensures long-term pressure stability and reduces the risk of waterlogging and air migration.

Key Product Specifications

• Total Volume: 27.7 gallons
• Connection Size: 3/4" NPT side outlet
• Maximum Working Pressure: 90 psi
• Diaphragm Material: Certified synthetic SBR rubber
• Shell Construction: Carbon steel with corrosion-resistant powder coating

System Integration and Performance

• Application: Designed for closed-loop hydronic systems using water or glycol-based fluids
• Pressure Stabilization: Absorbs system expansion to maintain constant operating pressure
• Pre-Charged: Supplied with factory air charge, field-adjustable to match system static pressure
• Installation Orientation: Vertical mounting on return piping or wall-mounted with bracket (not included)

Installation Guidance

The ZHT105 must be installed in accordance with local mechanical codes and system design specifications. It should be mounted vertically in a location where it can be isolated for service and where system pressure is at its lowest (typically near the boiler or air separator on the return line). Ensure that the air pre-charge is adjusted prior to filling the system. Installation is recommended to be performed by a licensed plumbing or HVAC professional.

Typical Applications

Suited for mid-to-large capacity residential hydronic heating systems, including multi-zone baseboard, radiant panel, and commercial water-source heat loop systems requiring stable pressure control and reliable thermal expansion management.