Immergas Zeus Maior 24

The Immergas Zeus Maior 24 is a wall-mounted, fan-assisted, room-sealed combination boiler designed for both central heating and domestic hot water supply. It incorporates a 60-litre unvented hot water storage cylinder and features a modulating gas valve with fully automatic direct burner ignition. The boiler is suitable for use with either Natural Gas or LPG, but must be converted if switching between gas types. It comes fully assembled and tested with a pump, diverter valve, pressure relief valve, expansion vessel, and pressure gauge.

Function Description:

The boiler provides central heating with outputs ranging from 10.5 kW to 27.9 kW and domestic hot water at temperatures up to 60°C with flow rates up to 17 litres/min (at a 60°C temperature rise). The central heating system is sealed and pressurised, designed to operate with flow temperatures up to 80°C. The domestic hot water system is an unvented storage type, typically supplied by a cold water storage tank and a pressure boosting pump, providing water pressure between 1 and 3 bar. An air cushion at the top of the storage vessel provides expansion for the domestic hot water.

Important Technical Specifications:

Heat Output:
- Nominal Heat Input: 30.3 kW (26030 kcal/h)
- Min. Heat Input: 12.2 kW (10466 kcal/h)
- Nominal Heat Output (useful): 27.9 kW (24000 kcal/h)
- Min. Heat Output: 10.5 kW (9000 kcal/h)
Gas Type: Natural Gas (G20), Butane (G30), Propane (G31)
- Supply Pressure: 20 mbar (G20), 29 mbar (G30), 37 mbar (G31)
- Nozzle diameter: 1.3 mm (G20), 0.75 mm (G30/G31)
Heating System:
- Max working pressure heating circuit: 3 bar
- Max working temp heating circuit: 90°C
- Adjustable temp heating: 43-90°C
- Expansion Tank Total Volume: 8 L
- Expansion Tank preload: 0.8 bar
- Water contained in boiler: 4 L
- Available head with flow rate 1000 l/h: 29.4 kPa (3.0 mH2O)
Domestic Hot Water:
- Useful heat output hot water production: 27.9 kW
- Adjustable temp domestic hot water: 20-60°C
- Hot water storage capacity: 60 L
- Continuous hot water flow rate @ ΔT = 30°C: 13.9 l/min
- Boiler weight filled: 138 kg
- Boiler weight empty: 74 kg
Electrical:
- Electrical connection: 230V/50Hz
- Nominal Absorption: 0.76 A
- Electrical power: 155 W
- Power absorbed by circulating pump: 90 W
- Power absorbed by fan: 35 W
- Equipment electrical system protection: IP44
Flue Gases:
- Flue gas production @ nom output: 67 kg/h (G20), 69 kg/h (G30), 71 kg/h (G31)
- Flue gas temperature at nominal output: 115°C (G20), 117°C (G30), 120°C (G31)
Dimensions:
- Height: 900 mm
- Width: 600 mm
- Depth: 450 mm
Connections:
- Gas Connection: 3/4"
- CH Connection: 3/4"
- DHW Connection: 1/2"
Minimum Clearances for Servicing:
- Top: 200 mm
- Bottom: 150 mm
- Side: 10 mm
- Front: 600 mm

Usage Features:

The boiler operation is automatic once the gas valve is open and the operating mode switch is set to "Hot Water" or "Hot Water/Heating".

Controls:
- Heating temperature selector (1)
- Domestic hot water temperature selector (2)
- Boiler over temperature and flue block red indicator (3)
- Power On green indicator lamp (4)
- Operating mode and Reset switch (5)
- Lockout red indicator lamp (6)
- Boiler thermometer (7)
- Boiler manometer (8)
Operating Modes:
- Hot Water (I): Central heating temperature setting (1) is inactive; domestic water temperature is controlled by selector (2).
- Hot Water/Heating (III): Central heating temperature is set using selector (1); domestic hot water temperature is set using selector (2).
- Temperatures are adjusted by turning selectors clockwise (raise) or anticlockwise (lower).
Safety Features:
- Overheat lockout: Red indicator lamp (3) on. Occurs if boiler temperature exceeds 100°C. Reset by turning main switch (5) to Reset position.
- Flue blockage: Red indicator lamp (3) on. Occurs if there's a problem with the flue. Reset by turning main switch (5) to Reset position.
- Ignition lockout: Red indicator lamp (6) on. Occurs if the boiler fails to light within 10 seconds. Reset by turning main switch (5) to Reset position. This can happen if the gas supply is interrupted or after prolonged disuse.
- Anti-freeze protection: Starts pump and burner when boiler water temperature falls below 4°C, stopping when it exceeds 42°C. This function is active in normal mode (not "lockout") and when electrically connected with the main switch set to Summer or Winter.
System Pressure: Before lighting, ensure manometer (8) indicates 1-1.2 bar. The 8-liter expansion vessel is pre-charged to 1.0 bar, suitable for systems up to 80 litres water content. For larger systems, an additional expansion vessel may be required.
Discharge Pipework: Discharge pipes from expansion relief valves must be routed to a tundish (1/2" or 15 mm pipe) and fall continuously. The tundish must be visible, within 500 mm of the appliance, and away from electrical devices. The minimum size of the discharge pipe downstream of the tundish is specified based on valve outlet size and pipe length/elbows.

Maintenance Features:

An annual maintenance check of the boiler and heating system is recommended to ensure optimal safety, performance, and operation.

Checks:
- System water pressure (1-1.2 bar).
- Flue side of the heat exchanger and main burner cleanliness.
- Visual inspection of flue extraction hood for wear or corrosion.
- Correct ignition and operation.
- Correct settings of the burner in domestic water and heating modes.
- Operation and adjustment of the boiler, including electrical main switch, system control thermostat, and domestic water control thermostat.
- Gas soundness of the gas intake circuit using a pressure gauge.
- Activation of the ionisation flame control gas device (activation time < 10 seconds).
- Visual inspection for water leakage or oxidation of fittings.
- Water safety valve outlets are not blocked, and tundish is clear.
- Expansion vessel charge (1.0 bar after discharging system pressure to zero).
- System static pressure (1-1.2 bar in cold conditions after recharging).
- Safety and control devices (temperature safety thermostat, air pressure switch) have not been tampered with.
- Integrity of boiler Magnesium Anode.
- Correct maintenance and condition of electrical installation (cables routed correctly, no black marking or burns).
Troubleshooting:
- Lack of water: Check system pressure; if frequent drops occur, contact a plumber.
- System flow NTC sensor fault: Boiler will not start; call a qualified technician.
- Domestic circuit NTC sensor fault: Boiler will not produce domestic hot water; call a qualified technician.
- No water circulating: Check shutoff valves, air in system, and circulating pump operation. If lockout occurs repeatedly, contact a qualified technician.
Draining:
- System: Use the special drain cock. Ensure filling valve is disconnected.
- DHW tank: Close cold water inlet cock, open a domestic hot water cock to allow air, then use the special drain cock.
Cleaning: Use damp cloths and neutral detergent for the casing. Avoid abrasive or powder detergents.
Flue System Maintenance: Ensure the flue slopes slightly towards the outlet (1-2 degrees) for condensate drainage, is adequately supported, and is straight. Do not use chemicals, detergents, or solvents for assembly; clean water may be used for seals. Thoroughly test for leaks after installation.