2 Gal. Hydronic Expansion Tank for Boiler System with Valve

Amtrol FILL-TROL 389767 – 2 Gallon Expansion Tank with Integral Fill Valve for Hydronic Systems

The Amtrol FILL-TROL 389767 is a 2-gallon pre-pressurized expansion tank designed for closed-loop hydronic heating systems. This unit integrates a diaphragm-type expansion tank with a factory-installed pressure-reducing fill valve, eliminating the need for a separate fill assembly. The combined configuration streamlines installation and ensures stable system pressure control throughout heating cycles.

Constructed from deep-drawn steel and finished with a corrosion-resistant coating, the tank includes a sealed air cushion separated by a heavy-duty diaphragm. The integrated fill valve is factory preset and field-adjustable to accommodate system requirements.

Technical Specifications

• Tank Volume: 2 gallons
• Acceptance Volume: 1.0 gallon
• Pre-Charge Pressure: 12 psig (factory set)
• Maximum Working Pressure: 100 psi
• Maximum Operating Temperature: 240°F
• Diaphragm Material: Butyl/EPDM
• Connection Size: 1/2" NPT
• Tank Dimensions: 8" diameter x 13" height

Functional Features

• Integrated Fill Valve: Regulates system pressure automatically; eliminates separate fill valve requirement
• Diaphragm Separation: Internal rubber diaphragm isolates system water from air charge to prevent waterlogging
• Pre-Charged Configuration: Factory set air charge with Schrader valve for field adjustment
• Steel Shell: Deep-drawn design for consistent wall thickness and improved durability
• Compliance: Designed for closed-loop hydronic heating applications

Installation Considerations

The FILL-TROL should be installed vertically on the cold water supply line leading to the boiler, typically at the point of lowest system pressure. Verify that the factory pre-charge matches the required system fill pressure. Installation must conform to local mechanical codes and manufacturer specifications. It is recommended that setup and commissioning be performed by a licensed HVAC or plumbing contractor familiar with closed-loop expansion systems.

Recommended Applications

Designed for use in residential hydronic heating systems, including baseboard, panel radiator, and radiant floor loops. Suitable for systems with moderate fluid volume requiring integrated pressure control and expansion capacity in a compact footprint.