Charging unit Laddomat 21-100 (opening temperature: 72°C) - insulated with electronic pump

Laddomat 21-100 with an electronic pump is designed to:

• enable the boiler to quickly reach high operating
  temperature during ignition.

• heat up cold water at the bottom of the boiler during charging, so
  that the boiler does not rust as a result of corrosion processes.

• ensure high and stable temperature in the tank and low
  flow to achieve optimal stratification in the boiler.

• after heating is complete, discharge heat to the storage
  tank.

• in case of power outage or pump shutdown, discharge heat from
  the boiler to the storage tank thanks to a built-in gravitational
  circulation system.

Laddomat 21-100 operates automatically provided that the pump on/off switching system is automated. Laddomat requires no special supervision or servicing.

Function description

Boiler ignition
To ensure high performance levels and low emissions, it is very important that the boiler quickly reaches high operating temperature. This will occur if the circulation pump is started immediately after ignition begins. In this way, unnecessary cooling of the boiler by water from the lower part of the tank is prevented. The pump can be started in three different ways, see page 4. The image below shows the beginning of boiler heating. The pump has been started. The thermal valve has not yet begun to open.
The cone on the automatic circulation valve is held tightly against the tank due to pump pressure.

Operating phase
The boiler has reached operating temperature. The thermal valve has opened and injects cold water from the tank.
Water supplied to the bottom of the tank has a temperature of 5-20°C at the initial temperature of the thermostatic element. The higher the boiler output and the higher the water temperature leaving the boiler, the more cold water is supplied from the bottom of the boiler. This factor is exactly what allows Laddomat 21-100 to achieve a clear boundary, i.e. stratification = tank loading during startup for all possible types of boilers.

Final phase
During the final charging phase, the flow throttle "by-pass" in the Laddomat 21-100 module leading to the upper part of the tank is completely closed. Water is discharged entirely to the storage tank, which is thus fully charged.

Gravitational circulation when heating is complete

If a thermostat is installed in the flue pipe or similar device, the pump will be switched off immediately after the fire is extinguished. The advantage of quickly switching off the pump after the fire is extinguished is that cold return water from the radiator circuit flows with the help of automatic gravitational circulation to the bottom of the boiler. The heat stored in the boiler is transferred to the upper part of the tank and is used to heat the building. Stopping the pump after heating is complete, either automatically or manually, is important for another reason. Otherwise, hot water in the tank would mix with cold return water from the radiator circuit, which would cause a temperature drop until the thermal valve closes. When the tank is heated to 90°C and the thermal valve closes at 75°C, the temperature of the entire tank contents would drop to that temperature if the pump were not switched off.

Gravitational circulation during power outage

If a power outage occurs during boiler operation, automatic gravitational circulation is activated thanks to an easily opening check valve – provided that the water in the tank is colder than in the boiler. Automatic gravitational circulation is created as a result of the difference in weight between lighter hot water and heavier cold water. When the tank is completely filled to the bottom, gravitational circulation is minimal and the boiler may still boil. Boiling can be prevented by supplying a small amount of cold water directly to the bottom of the boiler using the system filling tap. In case of longer power outages, the entire building can be heated using gravitational circulation, provided that the piping installation and pipe diameter have been adapted for this purpose. The heating intensity must be adjusted to the power that can be transferred to the storage tank using gravitational circulation. 

Connecting Laddomat to central heating system