Differences Between Solar Expansion Tank And Hydronic Heating Tank｜Aquasky
Understanding the differences between solar expansion tank and hydronic heating tank is key to achieving optimal performance, safety, and durability in heating systems. This article explores the unique applications, design features, and functional requirements that set these two types of expansion tanks apart.
APPLICATION AND PURPOSE
• Solar Expansion Tanks: Used in solar thermal systems, which harness solar energy to heat a glycol-based fluid. These tanks manage the thermal expansion of heat transfer fluids (often glycol-based) that can reach extremely high temperatures, especially during stagnation periods. During these high-temperature periods, the fluid expands significantly, and the expansion tank accommodates this increase, preventing pressure build-up that could damage the system.
• Hydronic Heating Tanks: Used in traditional water-based heating systems, such as space heating and domestic hot water heating. Their primary purpose is to absorb the modest expansion of water as it heats and cools, maintaining consistent system pressure.
TEMPERATURE AND PRESSURE RATINGS
• Solar Expansion Tanks: Built to handle high temperatures and pressures in solar heating systems. They can operate at temperatures up to 130°C (270°F) and pressures typically between 2-3 bar (30 - 45 psi) with the capacity to withstand steam generation during stagnation when solar collectors can exceed 200°C (410°F).
• Hydronic Heating Tanks: Designed for lower temperatures, usually around 60°C (140°F), and operate under significantly lower pressures, typically around 1-2 bar (15-30 psi). The maximum temperature for most hydronic systems is about 70°C (158°F).
FLUID COMPATIBILITY
• Solar Expansion Tanks: Constructed to be compatible with glycol-based heat transfer fluids, which can be prone to boiling at high temperatures. The materials in solar tanks are chosen for resistance to degradation from glycol and its chemical effects.
• Hydronic Heating Tanks: Use water as the heat transfer medium, which does not require specialized chemical resistance. Therefore, hydronic tanks can use standard materials, as they don’t encounter aggressive chemicals or extreme temperatures.
DESIGN FEATURES
• Solar Expansion Tanks: Typically incorporate a high-temperature-resistant bladder or membrane that separates the solar fluid from pressurized air, allowing them to handle significant volume changes due to both thermal expansion and phase change (liquid to steam) during stagnation.
• Hydronic Heating Tanks: Use a flexible diaphragm, usually made of butyl rubber or EPDM, which separates air from water. This design provides a “cushion” effect to manage pressure changes as water expands and contracts during normal operation.
SIZING CONSIDERATIONS
• Solar Expansion Tanks: Proper sizing is critical due to potential rapid pressure increases from steam formation. The acceptance volume of solar expansion tanks should exceed 10% of the system’s liquid volume, with additional capacity for steam generated during stagnation.
• Hydronic Heating Tanks: While sizing is also important in hydronic systems, the calculations are generally simpler due to the lower temperature ranges and pressures. Sizing is based on system volume and expected temperature fluctuations without the need to account for steam generation.
AQUASKY SOLAR-PLUS AND HYDRO-PLUS EXPANSION TANKS
Understanding the difference between these two types of tanks, AQUASKY has expertly engineered models to meet each system's unique demands. AQUASKY Solar Expansion Tank (Solar-Plus) is designed to handle high temperatures and pressures typical in solar thermal systems, accommodating significant thermal expansion and steam generation during stagnation periods. Constructed with an EPDM diaphragm, it ensures durability and reliability even under extreme conditions.
Meanwhile, AQUASKY Hydronic Heating Tank (Hydro-Plus) is tailored for conventional hydronic heating applications, efficiently absorbing moderate water expansion as it heats and cools, thereby maintaining consistent system pressure. Both AQUASKY tanks provide optimal safety, efficiency, and longevity in their specific applications, supporting solar and hydronic heating systems with exceptional performance and reliability.
For more information, visit our website: Aquasky.com
• For Solar Expansion Tanks: Solar Plus
• For Hydronic Heating Tanks: Hydro Plus
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CONCLUSION
In summary, solar expansion tanks are engineered for high-temperature, high-pressure environments typical of solar heating systems, while hydronic heating tanks are designed for lower temperatures and pressures associated with conventional water-based heating systems. This distinction is crucial for ensuring system safety, efficiency, and longevity in their respective applications.