Rinnai RCB Series 301,000 BTU Indoor Natural Gas Wall Mounted Commercial Condensing Solo Boiler - RCB301AN

Power Rinnai RCB301AN 301,000 BTU Wall-Hung Commercial Condensing Solo Boiler

Right-size building heat with a compact, high-efficiency package. The Rinnai RCB301AN delivers 97% thermal efficiency and a wide 10:1 turndown (30,100–301,000 BTU/h) to match real-time load and trim fuel use. A 316L stainless-steel water-tube heat exchanger resists corrosion, while a 7″ LCD touchscreen and built-in Wi-Fi/BMS make setup and monitoring straightforward. Flexible 4″ direct-vent options (PVC/CPVC/PP) and a light, wall-hung form factor simplify retrofit installs and service in tight mechanical rooms.

• Brand: Rinnai
• MPN: RCB301AN
• Type: Wall-hung commercial condensing heat-only (solo) boiler, indoor
• Size/Capacity: 301,000 BTU/h max input; 30,100 BTU/h min; AHRI heating capacity 254,000 BTU/h
• Material/Finish: 316L stainless-steel water-tube heat exchanger; steel cabinet
• Performance: 97% thermal efficiency; setpoint 86–180 °F (CH); sound level ~55 dB(A)
• Connections/Fit: Gas 1″ NPT; CH supply/return 1-1/4″ NPT; condensate drain 1″ NPT (3/4″ min pipe)
• Venting: 4″ PVC/CPVC/PP (and stainless) direct-vent, twin-pipe or concentric; room-air option; exhaust run 10–140 ft, intake 0–140 ft (equiv.); high-altitude derates vent length
• Dimensions: Approx. 33.1″ H × 19.4″ W × 21.3″ D; weight 170 lb
• Included: Wall-mount bracket & screws; 75 PSI pressure-relief valve; outdoor temperature sensor; manuals/warranty card
• Certifications: ANSI Z21.13 / CSA 4.9; ASME; Low-NOx; Wi-Fi capable; BMS 0–10V & Modbus (BACnet/LonWorks adapters optional)
• Warranty: Heat exchanger 10 years (non-prorated); parts 1 year; labor 1 year (commercial)

Save Energy & Lower Operating Costs

A condensing design and 10:1 turndown let the RCB301AN modulate precisely to demand, delivering up to 97% thermal efficiency for reduced gas use versus non-condensing units. Outdoor reset is standard to optimize water temperature and comfort as conditions change.

Everyday Heat You Can Count On

With an AHRI certified heating capacity of about 254,000 BTU/h and quiet operation (~55 dB(A)), the boiler supports steady output for schools, restaurants, and light commercial buildings without oversizing multiple tanks or floor space.

Durable Materials, Easier Care

The 316L stainless-steel water-tube heat exchanger resists corrosion for long service life. Removable panels provide 270° access to internals for faster maintenance. Safety features include flame monitoring, high-limit protections, blocked-vent switch, and freeze protection.

Installer-Friendly Venting & Piping

Vent with 4″ PVC/CPVC/PP (or stainless) in twin-pipe or concentric layouts—exhaust runs from 10 to 140 ft and intake up to 140 ft equivalent. Piping is straightforward: 1″ gas, 1-1/4″ CH supply/return, and 1″ condensate drain (3/4″ min pipe). Units ship NG; LP conversion kits are available.

Sized Right For Mechanical Rooms

The compact 33.1″ × 19.4″ × 21.3″ cabinet weighs only 170 lb, fits through standard doorways, and mounts with the included bracket—ideal for retrofits and tight spaces.

Smart Controls & Building Integration

A 7″ LCD touchscreen speeds commissioning. Standard Wi-Fi enables remote monitoring, while built-in 0–10V BMS input and Modbus streamline integration (optional BACnet/LonWorks adapters). Integrated pump relays (boiler, system, indirect) reduce add-ons; note that the circulators themselves are not included.

Scalable Systems, Common Venting

Cascade up to 8 boilers with equal runtime logic to meet higher loads, and common-vent up to 4 wall-hung units on properly sized PVC/PP where code allows. Follow the manual for vent sizing, elbow equivalencies, and altitude adjustments.

Want to learn more about this boiler? Read more about it in our article on the best steam boilers.