Noritz 20kW staged-combustion gas wall-hung boilers are designed for residential use, combining space heating and domestic hot water in one product. Staged combustion adjusts heat output in steps instead of switching fully on and off, helping reduce energy use and keep water temperature steadier. Wi-Fi smart control is available, and temperature settings can be adjusted from 30°C to 80°C, depending on heating and hot water needs. These wall-hung boilers can be used with residential HVAC applications such as floor heating systems as well as radiator heating, and noise can be as low as 42 dB for quieter daily use.
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Staged Combustion
Full Combustion
Benefits of Staged Combustion
Heating temperature settings cover 30–80°C, which works well across different home heating needs
An outdoor flue discharge design is used to improve efficiency and reduce energy use
Hot water stays more stable during use, including multi-point demand (for example, two outlets used close together)
Noise levels can be as low as 42 dB(A) for quieter operation
Active anti-freeze protection supports stable operation in colder weather
Technical Specifications
Model
GQH-20H1FFAI
Rated heat input
20 kW
Rated heat output
18 kW
Minimum heating output
8.1 kW
Minimum DHW output
4.6 kW
Minimum start-up flow
2.5 L/min
Thermal efficiency
≥89%
Hot water flow (ΔT = 25°C)
14 L/min
Dimensions (H × W × D)
740 × 440 × 310 mm
Weight
32.5 kg
Water-flow servo motors
0
Staged combustion
Yes
Circulation pump
1
0.5°C temperature step control
No
Heating temperature range
30–80°C
Hot water temperature range
35–60°C
Noise level (sound power / sound pressure)
≤53 / ≤39 dB
Wi-Fi
Yes
Component Overview
Combustion Fan
A fixed-speed fan is used for stable operation and broad compatibility. It starts reliably and works well even under higher-load conditions.
Electronic Controller
The controller supports accurate temperature control and efficient operation. It also includes multiple safety protections, user-friendly controls, and built-in fault detection to make troubleshooting and maintenance easier.
Sealed Combustion Chamber
The sealed combustion chamber is designed with insulation and sound-reducing materials to help protect internal parts and reduce noise. The H-series wall-hung boilers also use additional noise-control measures, with sound levels that can be as low as 42 dB(A)*.
Noritz Water Pump
Noritz water pumps are designed for quieter operation to improve comfort in daily use. They also include smart self-protection features that help reduce the risk of faults over time.
Sectional Valve
The sectional valve supports staged combustion control, so flame output can be adjusted in steps. This makes control more stable and more precise during operation.
Five-Stage Heat Exchanger Design
A five-stage heat exchanger structure helps keep the overall size compact while improving heat transfer. Thanks to the larger main tubes and a longer heat-exchange path, more heat can be captured and used efficiently.
Italian SIT Proportional Valve
A proportional valve from the Italian brand SIT is used to adjust gas flow and pressure. Since the adjustment is more precise and reacts quickly, the burner can run more smoothly and waste less gas, which improves efficiency.
Expansion Tank
The expansion tank helps absorb pressure changes in the water circuit as temperatures rise and fall. By keeping pressure more stable, it protects key components and supports more consistent operation over time.
Component Overview
Installation Dimensions
Applications
Radiator heating: flexible temperature settings (30–80°C) to match different rooms and seasons
Shower comfort: more stable hot water, so temperature changes feel less noticeable (about ±1°C)
Floor heating: warms up faster for daily use (about 30 minutes in typical conditions)
Kitchen + bathroom use: Designed for multi-point hot water use, so the kitchen and bathroom can run at the same time with less interference
NORITZ: From Japan, Serving Customers Worldwide
Headquartered in Japan, Noritz has focused on the development of heating systems and hot water technologies for more than half a century. Over the years, Noritz has built long-term partnerships in different markets by keeping the focus on three basic principles: energy saving, comfort, and stable performance. By combining strict supply chain screening with localized product adjustment, Noritz supports dealers and engineering contractors with tankless water heating solutions that remain highly competitive.
Staged Combustion
Full Combustion
