Lennox X6527 – Honeywell TK300-30/U Hydronic Heating Expansion Tank is engineered to manage thermal expansion in closed-loop hydronic heating systems, helping maintain consistent system pressure and protect critical HVAC components. Designed for residential and light commercial hot water heating applications, this 4.4-gallon expansion tank absorbs excess pressure created as water heats and expands, reducing stress on boilers, pumps, valves, and piping.

This OEM-quality hydronic expansion tank features a durable steel construction with an internal diaphragm that separates system water from the air charge, ensuring long-term reliability and stable performance. The 1/2 inch male threaded connection allows for straightforward installation into compatible hydronic systems. The Honeywell TK300-30/U is commonly used as a direct replacement in Lennox hydronic heating systems and is suitable for new installations or system upgrades where pressure control and equipment protection are critical.

Designed to meet professional HVAC standards, this expansion tank helps extend system lifespan, improve operational efficiency, and reduce the risk of pressure-related failures. Ideal for contractors and homeowners looking for a dependable, OEM-compatible hydronic expansion solution.

Key features and benefits:

Hydronic heating expansion tank for closed-loop hot water systems
4.4-gallon capacity designed to absorb thermal expansion
Internal diaphragm design for consistent pressure control
Durable steel construction for long service life
1/2 inch male threaded connection for easy installation
OEM-compatible replacement for Lennox hydronic heating systems
Suitable for residential and light commercial HVAC applications

Applications:

Hot water boilers
Hydronic baseboard heating systems
Radiant floor heating systems
Closed-loop residential and light commercial hydronic systems

Technical overview:

Brand: Honeywell
Catalog number: X6527
Model / part number: TK300-30/U
Tank capacity: 4.4 gallons
Connection size: 1/2 inch male
System type: Hydronic heating expansion tank

This Lennox X6527 Honeywell TK300-30/U expansion tank is a reliable choice for maintaining proper pressure balance in hydronic heating systems while delivering OEM-level quality and long-term performance.