Important parts of the boiler are pumps, 3-way valves and temperature sensory test probe, PT 100 probe. Heating circuit temperature regulation is conducted by opening or closing 3-way valve.

If the set temperature is over the measured one, the valve opens and releases hot water from the boiler into the heating system which heats the radiator which then releases the heat into the surroundings. The cooled water goes back into the process. In the situation where set temperature is lower than the measured, the 3-way valve opens and releases returning cool water instead of hot.

Current temperature of the room is 10 ℃. The task is to set the wanted temperature between 14 and 30 ℃.

˝Wanted temperature is close to the current temperature, so the 3-way valve is set into the position to mix hot with the returning cool water˝

˝Wanted temperature is higher than the current temperature, so the 3-way valve is set into the position to release only hot water˝

˝Wanted temperature is lower than the current temperature, so the 3-way valve is set into the position to release only returning cool water˝