MKB 400-3 A - Chauffe-eau et chaudière Junkers - Free user manual and instructions
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| Product Type | Gas-fired combi boiler (water heater and central heating) |
| Model | MKB 400-3 A |
| Brand | Junkers |
| Dimensions (approx.) | 400 x 300 x 800 mm (W x D x H) |
| Weight (approx.) | 35 kg |
| Power Supply | 230 V ~ 50 Hz |
| Gas Type | Natural gas (G20) or LPG (G31), convertible |
| Heating Output (approx.) | 24 kW (adjustable range) |
| DHW Output (approx.) | 30 kW (instantaneous) |
| Main Functions | Central heating and domestic hot water production; modulating burner; digital control panel; frost protection; summer/winter mode |
| Safety Features | Flame failure device, overheat protection, low water pressure cut-off, gas pressure switch |
| Maintenance | Annual service by qualified technician; clean burner and heat exchanger; check gas pressure and flue |
| Spare Parts Availability | Genuine parts available through Junkers service centers and authorized dealers |
| Repairability | Modular design; most components replaceable; technical documentation available |
| Efficiency Rating | ErP class: A (heating) / A (DHW) typical |
| Flue Type | Room-sealed (concentric) for balanced flue installation |
| Control Interface | Digital display with push buttons; optional external thermostat connection |
| Installation | Wall-hung; requires gas, water, and electrical connections; must be installed by a certified professional |
Frequently Asked Questions - MKB 400-3 A Junkers
What is the correct gas pressure for this boiler?
The inlet gas pressure should be 20 mbar for natural gas (G20) or 30-37 mbar for LPG (G31). Check the label or consult the manual for exact specifications.
How do I reset the boiler after a fault?
Press the reset button (often marked with a flame symbol) for 2-3 seconds. If the fault persists, consult the error code on the display and refer to the troubleshooting section.
What is the recommended water pressure?
The filling loop should be set to about 1.0-1.5 bar when cold. If pressure drops below 0.5 bar, refill the system carefully to avoid overpressurization.
Can I use it with a solar thermal system?
Yes, the MKB 400-3 A can be integrated with solar water heating via a heat exchanger or buffer tank. Contact a professional for compatibility.
How often should I service the boiler?
An annual service by a Gas Safe registered engineer is mandatory to ensure safe and efficient operation. It includes cleaning the burner and checking flue gases.
What does error code E01 mean?
E01 typically indicates a flame failure. Check gas supply, ignition electrode, and gas valve. If it persists, call a technician.
Is the boiler suitable for large homes?
With a heating output of 24 kW, it is suitable for medium-sized homes (up to 200 m²). For larger homes, consider a higher output model.
Can I install it myself?
No, installation must be performed by a certified professional in compliance with local regulations. Improper installation can void the warranty.
How do I adjust the hot water temperature?
Use the temperature setpoint dial on the control panel. Typical settings range from 40°C to 65°C. For safety, do not exceed 60°C.
Where can I find spare parts?
Genuine Junkers spare parts are available from authorized distributors and service centers. Use the model number MKB 400-3 A when ordering.
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