Caleffi 324 Series 4-Way Thermostatic Mixing Valve 1 inch x 1/2 inch 60°C DZR Brass

In a solid fuel boiler installation, the return water temperature must be kept above 60°C to prevent condensation and corrosion inside the boiler. This Caleffi 324 series 4-way thermostatic mixing valve automatically blends hot supply water with cooler return water to maintain a fixed return temperature of 60°C, protecting the boiler and ensuring efficient operation. The valve features two 1" female threaded connections for the boiler loop and two 1/2" female threaded connections for the system loop, all in dezincification-resistant brass for long service life.

Key specifications

• Product type: Thermostatic mixing valve (4-way)
• Function: Boiler return temperature control
• Connection sizes: 2 x 1" (DN25) and 2 x 1/2" (DN15)
• Connection type: Female threaded (BSPP - ISO 228-1)
• Fixed temperature setting: 60°C (140°F)
• Body material: Dezincification resistant brass
• Max operating pressure: 10 bar (145 psi)
• Max inlet temperature: 100°C (212°F)
• Kv value: 4.0 m³/h
• Media compatibility: Water, glycol solutions (up to 50%)
• Seal material: EPDM
• Thermostatic element: Wax-filled
• Installation orientation: Any position
• Application: Solid fuel boilers, biomass boilers

Why choose it

The integrated bypass control and corrosion-resistant DZR brass body make this valve a reliable choice for demanding heating systems. The wax-filled thermostatic element responds quickly to temperature changes, ensuring stable return temperatures and protecting your boiler from thermal shock and acidic condensate. Suitable for use with water or glycol solutions up to 50%, it offers flexibility for various system designs.

Ideal use cases

• Solid fuel boilers (wood, coal, biomass) requiring return temperature protection
• Heating systems with mixed supply/return temperatures
• Retrofit or new installations where boiler longevity is a priority
• Systems using glycol-based heat transfer fluids

Good to know

The valve can be installed in any orientation, simplifying piping layouts. The 4-way design allows for direct connection between boiler and system without additional tees. Regular maintenance is minimal thanks to the durable EPDM seals and DZR brass construction. Always ensure system pressure does not exceed 10 bar and inlet temperature stays below 100°C.