Laddomat MR 40

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Laddomat MR 40 is a charging unit for boilers with integrated hot water heater and mixing valve. The thermal 3-way valve has 2 non-return valves to ensure that the flow can go in two directions.


  • Sys 40 – Charging/discharging between boiler/tank.
    Charging from the boiler with an integrated water heater and mixing valve to accumulator tank/tanks. Discharging from the tank starts when the boiler temperature drops. When the tank is cold, additional heating may be started.
  • Sys 41 – Charging/discharging between boiler/tank with burner control.
    To increase water volume for e.g. pellet boilers with built-in hot water heater and mixing valve.

Sensors that are not used for control can be used for temperature reading in a separate menu.

Scope of delivery:

Sys 40 / Sys 41 Valve package Laddomat MR 40 with:

  • Laddomat MR, complete.
  • Charging and discharging valve Laddomat 41-200, with 2 x built-in non-return valves.
  • 2 x pumps, Laddomat LM 6A, 130 mm.
  • 3 x ball valves.
  • Submersible tube for boiler sensor. Connection R10, L = 50-480 mm
  • 3 x 3-bulb submersible tubes for bulbs with D=6 mm. R15, L=150 mm.
  • 2 x sensor holders and hose ties for pipe fitting
  • EPP insulation for the thermal valves supplied as standard.

For boiler output max. 45 kW.

Function Sys 40


When firing up, the boiler quickly reaches its working temperature. The charging pump starts when the boiler sensor is hot. Hot water from the boiler top is mixed with cold water from the bottom of the tank to approximately 60°C in the Laddomat 41-200 valve, and into the bottom of the boiler to be re-heated. No risk of condensation which can cause corrosion due to low bottom temperature. The tank top is supplied with hot water at a low flow, providing efficient separation of the heat in the tank.


When firing stops, the boiler cools and the charging pump is stopped when the boiler sensor is cold. When the boiler has cooled so that the boiler sensor is less than the set temperature, the discharging pump starts, and the now cold water at the bottom of the boiler is pumped over to the bottom of the tank. At the same time, hot water is sent to the top of the boiler. This takes place at a low flow thanks to that the Laddomat 41-200 valve is equipped with a strong choke. Efficient separation of the heat is thereby achieved both in the tank and the boiler. Discharging can only be started if the tank is warmer than the boiler.

Additional heating

Discharging can be interrupted at the desired temperature at the tank top sensor and, the additional heating, if any, may then be started in addition.

Function Sys 41 – Burner control + charging/discharging

The burner is started by the tank top sensor. It continues until the sensor in the bottom of the tank exceeds the set temperature. When the burner stops, the tank empties little by little. When it is completely empty and the temperature at the sensor at the top of the tank is less than the set temperature, the burner re-starts. The charging pump can either start when the burner starts, or when the boiler exceeds the set temperature.