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Specifies the external measurements of the boiler unit and flue types.
Lists key operational parameters including heat input, flow rates, and pressures.
Details pump head availability and system capacity charts.
Identifies and labels various components within the boiler system.
Step-by-step guide for safely powering on the boiler.
Instructions for utilizing the boiler for domestic hot water.
Overview of the control panel and schematic diagrams for operation.
Procedure for operating the boiler exclusively for hot water.
Procedure for operating the boiler for central heating.
Illustrates the electrical connections and layout of the boiler.
Details on potentiometers P1 and P2 for CH and lighting power.
How thermistors control C/H and DHW temperatures.
Recommends annual servicing by competent persons.
Lists NOx and CO values for performance testing.
Instructions for safe and effective boiler cleaning.
Steps for removing the outer casing and combustion chamber panel.
Procedures for removing the gas valve and fan unit.
Instructions for accessing and removing the DHW flow switch and pressure switch.
Guide for removing and replacing the main heat exchanger and pump.
Steps for replacing the pressure relief valve and thermostats.
Instructions for replacing the control board and expansion vessel.
Flowchart for preliminary checks and identifying power or basic faults.
Diagnostic steps for pump and fan operation issues.
Troubleshooting for air pressure switch, spark generation, and burner faults.
Diagnosing safety shutdown triggers and specific operating faults.
Table correlating LED patterns with specific faults and information.
List of components with key numbers, descriptions, and part numbers.
The Chaffoteaux & Maury MX2 24-30 FF is a fanned flue combination boiler designed to provide both central heating and instantaneous domestic hot water. This service guide outlines its dimensions, technical data, functional characteristics, maintenance procedures, and fault-finding charts.
The MX2 24-30 FF boiler operates by heating water through a main heat exchanger, which then circulates through either the central heating system or a secondary heat exchanger for domestic hot water. The boiler is suitable for various flue types (C12, C32, C52) and incorporates a fanned flue system for efficient exhaust.
When a demand for central heating or domestic hot water is initiated, the boiler's control system activates the gas valve, allowing gas to flow to the multigas burner. An ignition sequence begins with a continuous high-speed spark, igniting the gas. A flame detection electrode confirms successful ignition, and an orange indicator bulb illuminates. For central heating, the modulating solenoid opens to allow the full gas rate, and the pump circulates heated water through the system. The central heating flow temperature is regulated by a thermistor, with an adjustment knob allowing users to set temperatures between 35°C and 85°C. The boiler is designed to minimize cycling, with a 3-minute delay before attempting to relight after the thermostat is satisfied, and the pump continues to run for 3 minutes after the burner switches off.
For domestic hot water, the boiler prioritizes this demand, interrupting central heating if both are active. When a hot water tap is opened and the flow rate exceeds 2 litres per minute, a DHW flow sensor activates a 3-way valve, directing the heated water through the secondary heat exchanger. The domestic hot water temperature is controlled by flow and return thermistors, with an adjustment knob allowing users to set temperatures between 40°C and 60°C. These thermistors anticipate temperature changes in the secondary heat exchanger, ensuring accurate regulation. If a flame is not detected within 8 seconds of ignition, security solenoids close, shutting off the gas, and a red lockout indicator bulb illuminates.
The boiler includes several safety features, such as an overheat security system, an air pressure switch to detect adequate air flow in the flue duct, and a pressure relief valve for the central heating circuit. An expansion vessel is integrated to accommodate changes in water volume within the heating system. The control panel provides indicators for power on, burner operation, and lockout/flame failure, along with a pressure gauge for the central heating system.
Operating the MX2 24-30 FF involves a straightforward switching-on procedure. Users must ensure the gas service tap at the gas meter and the main power are on. The central heating system pressure should be checked to be between 0.8 bar and 1.5 bar using the pressure gauge on the control panel. After opening the boiler's gas tap, the appliance is ready for use. Pressing the ON/OFF push button illuminates the "power on" light.
For hot water, the DHW thermostat knob should be turned clockwise. Opening a hot water tap will then activate the burner, indicated by an orange "burner on" light, and hot water will be supplied. For central heating, the main ON/OFF button must be in the "I" position, confirmed by a green light. The central heating selector switch should then be turned clockwise. The boiler will initiate heating if there is a demand from the room thermostat or the clock, and if the boiler temperature control is calling for heat.
The boiler's control panel allows for adjustment of both domestic hot water and central heating temperatures. The DHW knob adjusts the temperature between 40°C and 60°C, while the CH knob adjusts between 35°C and 85°C. In case of a lockout or flame failure, the reset button can be pressed to attempt relighting the boiler. The system prioritizes hot water demand, temporarily interrupting central heating to provide instantaneous hot water.
Routine servicing of the MX2 24-30 FF is crucial for continued efficient operation and compliance with gas safety regulations. It is recommended that the boiler be checked and serviced at regular intervals, typically once a year, by a competent, CORGI-registered person.
The service schedule includes several key operations:
Additional procedures that may be necessary include checking burner pressure and gas flow rates, cleaning the fan blades, and replacing components as needed. Combustion tests should be carried out using the test points in the flue turret.
Before any service work, the gas and electricity supplies must be isolated, and the appliance should be cool. Preliminary checks involve removing the outer case, verifying system pressure (at least 0.8 bar cold), checking solenoid operation, and confirming that the burner extinguishes fully when solenoids close in both DHW and CH modes. Ionization functions should be tested, and lockout should occur when the gas tap is turned off.
Cleaning the boiler casing should only be done when the boiler is switched off, using a damp cloth. Abrasive cleaning powders or liquids should not be used. The guide also provides detailed instructions for the removal and replacement of various components, including the outer case, combustion chamber, burner manifold, electrodes, gas valve, fan assembly, DHW flow switch plunger, pressure switch, DHW reed relay, main heat exchanger, insulation pads, pressure relief valve, NTC and overheat thermostats, safety thermostat, pump, and control board. These instructions emphasize draining the boiler and isolating supplies before component removal and greasing O-rings during reassembly. The expansion vessel requires removing the boiler from the wall for replacement.
General| Mounting | Wall-mounted |
|---|---|
| Output | 24 kW |
| Fuel Type | Natural Gas |
| Efficiency | 93% |
| Weight | 31 kg |
| Max Working Pressure | 3 bar |
| Ignition | Electronic |
| Flue System | Room-sealed |
| Warranty | 2 years |
| Condensing | No |
| Type | Combi |
