4.4 Gal. Boiler Expansion Tank with Purge

Amtrol 3000-125 Extrol – 4.4 Gallon Diaphragm Expansion Tank for Closed Hydronic Systems

The Amtrol 3000-125 Extrol is a 4.4-gallon pre-pressurized expansion tank designed for use in closed hydronic heating and chilled water systems. It accommodates the thermal expansion of system fluid, stabilizing internal pressure and protecting components from over-pressurization and hydraulic stress.

This diaphragm-style tank features a welded steel shell and a heavy-duty butyl/EPDM diaphragm that separates the system water from the air charge. The tank is pre-charged at 12 psi and includes a field-serviceable Schrader valve for pressure adjustment as needed during commissioning.

Technical Specifications

• Total Volume: 4.4 gallons
• Acceptance Volume: 2.2 gallons
• Connection Size: 1-1/4" NPT
• Pre-Charge Pressure: 12 psi (adjustable)
• Maximum Operating Pressure: 100 psi
• Maximum Temperature: 240°F
• Diaphragm Material: Butyl/EPDM
• Tank Construction: Deep-drawn steel with corrosion-resistant coating

Key Features and Functional Design

• Closed-System Compatibility: Suitable for hydronic heating and cooling circuits
• Internal Separation: Prevents waterlogging by isolating system fluid from air charge
• Factory Pre-Charged: Reduces field setup time and supports quick commissioning
• Schrader Valve: Allows pressure adjustments to match system static fill pressure

Installation Guidelines

Install the Extrol tank on the system return line, typically near the air separator or circulator inlet. Ensure vertical orientation with appropriate support to handle the full system pressure. Verify pre-charge pressure with a calibrated gauge before filling the system. Follow all applicable local mechanical codes and equipment manufacturer guidelines. Installation by a licensed HVAC or plumbing technician is recommended for proper sizing and system balance.

Intended Use

The Amtrol 3000-125 is intended for use in closed-loop hot water heating or chilled water systems. It is suited for residential and light commercial applications requiring reliable thermal expansion control in systems up to 100 psi operating pressure.