NORITZ Tankless Water Heater, Model GQH-40H2FFAAI
40kW Gas Combination Boiler, Dual Servo Control
- 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
Noritz 40kW gas combination boilers were developed for projects with high hot water demand. They are designed for high-end villas and light commercial applications, and the dual water-flow servo constant-temperature system helps keep outlet temperature stable even when multiple taps are used at the same time. They support both underfloor heating and radiator heating. The noise-reduction design of these gas boilers helps improve comfort, and Wi-Fi remote service support makes operation and maintenance more convenient in larger heating areas.
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
- PRO-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-40H2FFAAI |
| 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 | 40.5 kg |
| Water-flow servo motors | 2 |
| Staged combustion | No |
| Circulation pump | 1 |
| 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, which helps keep operation steady while reducing energy use and noise across different working conditions.
Electronic Control Unit
The electronic control unit supports accurate temperature control and efficient operation. Safety protections and built-in fault diagnostics make status checks and troubleshooting easier.
Sealed Combustion Chamber
Insulation and sound-damping materials are used on the side panels to help reduce heat loss and noise, while also helping limit vibration and wear during operation.
Noritz Water Pump
Designed for quiet running to improve comfort in daily use. Self-protection functions help reduce the risk of faults.
Dual Water-Flow Servo System
Controls both inlet and outlet water flow with high precision by coordinating the two flow paths in real time, it helps keep temperature steadier during multi-point hot water use.
Five-Pass Heat Exchanger Design
A five-pass heat exchanger keeps the unit compact while improving heat transfer. Larger main tubes and a longer flow path help absorb more heat.
Italian SIT Proportional Valve
Regulates gas flow and pressure with fast response and high control accuracy. This supports efficient combustion and helps reduce energy use.
Expansion Tank
Helps absorb pressure changes in the water system as temperature varies. It also helps buffer water hammer, protect key components, and support stable operation over time.
- Component Overview
- Installation Dimensions
- PRO-Control dual servo temperature control helps keep hot water temperature steady (up to ±0.2°C)
- Heating temperature range from 30–80°C supports different heating needs
- Works with Japanese-style dry underfloor heating for quicker comfort after start-up
- Quieter operation with noise as low as 42 dB(A)
- Wi-Fi remote access makes it simple to check operating status and confirm the unit is running normally
- Fine water-flow adjustment and fast response support stable temperature control throughout the day
Noritz H Series gas combination boilers provide an integrated solution for both space heating and domestic hot water, making them suitable for different areas of the home, including kitchens, bedrooms, and bathrooms. They can be paired with Japanese-style dry underfloor heating for on-demand comfort, while also helping improve common issues seen in traditional wall-hung boilers to deliver a more stable whole-home hot water experience.
As a trusted global partner in heating, Noritz is headquartered in Japan and focuses on competitive heating solutions for the mid- to high-end HVAC market. Noritz aims to address common pain points seen with traditional heating equipment, including noise, energy consumption, and maintenance. Flexible OEM/ODM customization support is also available to help partners serve higher-end residential and commercial HVAC projects with stronger profit potential.