- Other discontinued products
- Wall Hung Boilers Traditional
- Wall Hung Boilers Condensing
- Wall Hung Boilers Condensing single and modular station
- Floor Standing Boilers Steel
- Floor Standing Gas Boilers Cast Iron
- Floor Standing Boilers Cast Iron
- Floor Standing Boilers Steel Condensing
- Water softeners
- Water purifiers
- Water dispensers
- High-efficiency diffusers
- Osmosis and Microfiltration
- Polyphosphate feeders
- Feed pumps
- Water filters
- Other Discontinued Water Treatment products
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MEGAPREX N 92 N (cod. 0)
MEGA PREX N - N OPERATING PRINCIPLES
The boiler consists of 2 overlapped units of same capacity and one only control panel for both units. Each unit can work independently and the boiler can be operated partially. This means that all panel controls (burner switches, thermostats and thermometers) have been doubled. See paragraph 4.5 on connection. As an example, bi-thermostats TR1 and TR2 can be adjusted so that there is a 10°C intervention difference between each other (do not forget that knobs have a 60° to 90° regulation range with a 1/4 turn rotation). Flow water temperature after 2 equal flows have been mixed corresponds to mean temperature displayed by the 2 thermostats of each unit.
The boiler must be connected to a power supply of 230V/50Hz single-phase + ground, following the instructions below: The system must be in compliance with the SAFETY REGULATIONS IN FORCE. - Fit a bipolar line disconnection switch in conformity with CEI-EN regulations (contact opening of at least 3 mm). - Respect the L (phase) - N (neutral) connection - Use cables with a cross-section equal to or greater than 1.5 mm 2 - Refer to the wiring diagrams in this manual for any electrical operation. - Make the ground connections to an effective ground system.
MEGA PREX N - N CONTROL PANEL OPERATIONS
Use main switch (11) to power up the panel and all the connected devices. Switches (12) and (13) in turn, power off the plant burner and pump. Thermostat (21) is used to regulate boiler working pressure. Min pressure thermostat stops the plant pump during start up and until the boiler temperature has reached 50°C. In case of three-phase burners and/or pump or if electrical input exceeds 3A, remote contactors should be provided between the boiler control panel and the load. The electric line supplying the boiler control panel should be provided with a protection fuse-switch.
WARNING • For the electric connection of boilers exceeding 300.000 kcal/h rated power, the technician should make ready an additional (2nd) safety thermostat.
A - Operating burner light
B - Counter (optional)
22 - Safety
30 - Termometer
Before connecting the boiler, perform the following operations:
• Thoroughly clean all the system pipes in order to remove any foreign matter that could affect correct operation of the boiler;
• Check that the flue has an adequate draught, that there is no narrowing of passages and that it is free from debris; also check that other appliances do not discharge into the flue (unless designed to serve several utilities). See the regulations in force.
As a rule, regulations in force should be always observed. Premises in which boilers will be installed should be sufficiently ventilated and guarantee access for ordinary and extraordinary maintenance operations.
The pressurised boiler that now equips your heating system is so-called because it uses a burner provided with fan which introduces into the combustion chamber the exact amount of air necessary in relation to the fuel and maintains an overpressure in the furnace equivalent to all the internal resistances of the flue gas path as far as the boiler exhaust. At this point the fan pressure should have dropped to zero to prevent the flue connection pipe and the lower area of the flue itself from being under pressure and combustion gas leaks occurring in the boiler room. The connection pipe from the boiler to the base of the flue must slope upwards in the direction of the flue gas flow with recommended gradient of no less than 10%. Its path must be as short and straight as possible with the bends and fittings rationally designed in accordance with air duct criteria.
The paragraph Technical Specifications specifies the flue connection diameters of the boilers for lengths of up to 1 metre. For more winding paths, the diameter must be suitably enlarged.
Before starting the boiler, check that: - the rating plate specifications and power supply network (electricity, water, gas or fuel oil) specifications correspond; - the burner power range is compatible with the power of the boiler; - the boiler room also contains the instructions for the burner; - the flue gas exhaust pipe is operating correctly; - the air inlet supply is well dimensioned and free from any obstacle; - the manhole , the smokebox and the burner plate are closed in order to provide a complete flue gas seal; - the system is full of water and that any air pockets have therefore been eliminated; - the anti-freeze protections are operative; - the water circulation pumps are operating correctly. - The expansion vessel and the safety valve(s) have been connected correctly (with no interception) and are properly operating. - Check the electrical parts and thermostat operation.
The most common phenomena that occur in heating systems are: - Scaling Scale obstructs heat transfer between the combustion gases and the water, causing an abnormal increase in the temperature of the metal and therefore reducing the life of the boiler. Scale is found mostly at the points where the wall temperature is highest and the best remedy, at construction level, is to eliminate areas that overheat. Scale creates an insulating layer which reduces the thermal transfer of the generator, affecting system efficiency. This means that the heat produced by burning the fuel is not fully exploited and is lost to the flue.
%: fuel not used
mm: mm scale
- Corrosion on the water side Corrosion of the metal surfaces of the boiler on the water side is due to the passage of dissolved iron through its ions (Fe+). In this process the presence of dissolved gases and in particular of oxygen and carbon dioxide is very important. Corrosion often occurs with softened or demineralised water which has a more aggressive effect on iron (acid water with Ph <7): in these cases, although the system is protected from scaling, it is not protected against corrosion and the water must be treated with corrosion inhibitors.
FILLING THE SYSTEM
The water must enter the system as slowly as possible and in a quantity proportional to the air bleeding capacity of the components involved. Filling times vary depending on the capacity and characteristics of the system but should never be less than 2 or 3 hours. In the case of a system with closed expansion vessel, water must be let in until the pressure gauge indicator reaches the static pressure value pre-set by the vessel. Heat the water to maximum temperature and never over 90°C. During this operation the air contained in the water is released through the automatic air separators or through manual bleed valves. The water discharged from the system with elimination of the air is made up by the automatic or manual filling valve.