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The Riello Array V2.5 is a fully packaged, modular high-efficiency condensing boiler plant available from 800 MBH to 4,000 MBH input, designed to deliver plant-level redundancy within a single cabinet.

Each Array integrates multiple independent heat exchanger modules, providing high turndown, built-in redundancy, and simplified installation compared to traditional multi-boiler plants.

Modular Redundancy & Turndown

Each Array cabinet contains multiple independent modules:

• AR 800: 2 × 400 MBH modules
• AR 1000–4000: 500 MBH modules per section

Because each module operates independently, adjacent modules remain active if one is offline for service or maintenance. This provides internal redundancy typically achieved only with multiple separate boilers.

Turndown ratios include:

• Up to 40:1 per boiler
• Up to 320:1 per cascaded system (8 boilers / 64 modules)

This wide modulation range supports low-load seasonal efficiency and minimizes short cycling.

Combustion & Heat Exchanger Design

The Array utilizes a premix combustion system featuring a stainless steel mesh burner, modulating gas valve, and high-performance fan to maintain consistent air-fuel ratios across the full modulation range.

The patented Riello helix heat exchanger includes:

• AISI 316L stainless steel construction
• True counterflow 4-pass design
• High water velocity and large tube diameters to reduce scaling
• Vortex flow meters ensuring proper flow through each module
• Low waterside pressure drop

AHRI thermal efficiency is rated at 96.1%, with combustion efficiency up to 99%.

NOx emissions are <9 ppm at 3% O₂.

Controls & BMS Integration

Each unit includes a 7” graphic touchscreen controller with:

• Cascade management (up to 8 boilers)
• Real-time module input rate display
• Outdoor reset adjustment
• Error logging and commissioning access

Integrated Modbus communication is standard, with optional gateways for BACnet, Metasys, and LonWorks.

The control also supports 0–10V setpoint control and analog input for DDC integration.

Installation & Mechanical Advantages

The Array is engineered for simplified mechanical coordination:

• Single-point hydronic, electrical, fuel, and vent connections
• Small footprint designed to fit through standard doorways
• Venting options include CPVC, polypropylene, or AL29-4C stainless steel
• Individual pump per module eliminates need for a separate boiler circulating pump
• ASME design pressure: 80 PSI

All units are 100% live-fire tested prior to shipment.

Applications

The Riello Array is suited for:

• Multifamily central plants
• Commercial office buildings
• Institutional and healthcare facilities
• Retrofit boiler plant replacements

Its integrated redundancy, compact footprint, and high turndown ratio make it particularly effective in retrofit mechanical rooms where space and downtime risk are critical considerations.

Get in touch! Reach out to us at engineering@walesdarby.com