NORITZ Tankless Water Heater, Model GQH-40H3FFAQI
40kW Gas Combination Boiler, Dual Servo Control, Instant Hot Water
- Rated heat input 40 kW
- Rated heat output 36 kW
- Minimum start-up flow 2.5 L/min
- Hot water flow (ΔT = 25°C) 20 L/min
When a project needs higher output and faster hot water delivery, these 40kW wall-hung gas boilers are a solid choice for large apartments, villas, and light commercial use. Thanks to the 40kW output and instant hot water circulation, they handle heavier heating and hot water demand while helping reduce the wait at the tap. The wall-hung design takes up less space than floor-standing boilers, which helps in tighter mechanical rooms. Lower noise during operation makes day-to-day use more comfortable, and Wi-Fi remote service support makes it easier to check running status and handle routine maintenance.
PRO-Control dual hot-and-cold servo control keeps hot water temperature very stable, up to ±0.2°C*, helping solve common issues seen in traditional wall-hung boilers
Multi-point use without disruption: multiple kitchen and bathroom taps can be used at the same time with less temperature fluctuation
More comfortable showers year-round: less risk of “too hot” water in summer, and warmer water in winter
Water and gas work together: a stepper motor and gas proportional valve adjust output continuously to keep temperature under control
Fast response: quick calculations and real-time inlet flow adjustment help stabilize temperature sooner
Smart mixing: If water supply is interrupted and then returns, the gas boiler prevents a sudden rush of overly hot leftover water, helping reduce scalding risk
Upgraded three-pipe circulation system: in addition to the inlet and outlet lines, a dedicated return line creates a separate circulation loop for smoother hot water delivery
Built-in high-quality circulation pump: supports circulation loops up to 120 m and is designed to handle high temperature and corrosion for more stable operation
- The comparison images are based on Noritz internal testing and are for reference only. Actual performance may vary.
- Data is taken from a test report issued by Zhejiang Fangyuan Testing and Certification Group (Report No.: 2411305892).
- Some data is sourced from the Noritz laboratory
| Model | GQH-40H3FFAQI |
| Rated heat input | 40 kW |
| Rated heat output | 36 kW |
| Minimum heating output | 14 kW |
| Minimum DHW output | 1 kW |
| Minimum start-up flow | 2.5 L/min |
| Thermal efficiency | ≥89% |
| Hot water flow (ΔT = 25°C) | 20 L/min |
| Dimensions (H × W × D) | 738 × 510 × 350 mm |
| Weight | 41.5 kg |
| Water-flow servo motors | 2 |
| Staged combustion | No |
| Circulation pump | 2 |
| 0.5°C temperature step control | Yes (35–48°C) |
| 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 |
Variable-Speed Fan
Fan speed adjusts based on demand to support stable operation, lower energy use, and quieter running, while providing more precise airflow control across different scenarios.
Electronic Control Unit
Helps manage temperature accurately and improve efficiency. It also supports safety protections, user-friendly operation, and basic fault diagnostics for easier maintenance.
Sealed Combustion Chamber
Uses insulation and sound-damping materials to reduce heat loss and noise. Side-wall protection also helps reduce friction and vibration.
Noritz Water Pump
Designed for quieter operation and improved comfort, with self-protection functions that help reduce fault risk.
Built-in circulation pump
Supports the instant hot water function, reducing waiting time at the tap and helping cut down on water waste, while improving heating and hot water use.
Dual Water-Flow Servo System
Controls inlet and outlet flow more precisely. By coordinating two flow paths, it helps keep water temperature steadier during multi-point use.
Five-Pass Heat Exchanger Design
Helps maximize heat transfer in a compact layout, with a larger main passage and longer heat-exchange flow path for more effective heat absorption.
Italian SIT Gas Proportional Valve
Regulates gas flow and pressure with higher precision and fast response, helping support stable combustion and better energy use.
Expansion Tank
Helps balance pressure changes in the water system, compensates for volume changes caused by temperature shifts, reduces water hammer, and supports more stable operation.
- Component Overview
- Installation Dimensions
- Three-pipe instant hot water circulation helps reduce waiting time for hot water across the home
- PRO-Control dual servo temperature control helps keep hot water temperature steady (up to ±0.2°C)
- Can be paired with Japanese-style dry underfloor heating for quicker comfort after start-up
- Heating temperature can be set from 30–80°C to suit different heating needs
- Large glass touch display offers responsive control with a clean, straightforward interface
Noritz H Series wall-hung gas boilers combine space heating and domestic hot water, which is suitable for different areas of the home, including kitchens, bedrooms, and bathrooms. They can be used with Japanese-style dry underfloor heating for on-demand comfort, while also helping improve the overall stability of hot water temperature across the home.
Noritz is headquartered in Japan and has focused on space heating and hot water technology for more than 50 years. Noritz tankless water heaters feature efficient operation, consistent comfort, and stable performance over time. For dealers and project contractors, that means integrated solutions that cover underfloor heating and domestic hot water. With manufacturing based in China and flexible OEM/ODM support, Noritz (China) also helps partners adapt products to different HVAC project needs.