Ignition and adjustment of the solid fuel boiler

Below is the procedure for igniting a solid fuel boiler with a mechanical draught regulator, three-way thermostatic valve, and thermal accumulator, as indicated in the solid fuel boiler connection diagram.

Boiler preparation for operation

If the water was drained during the idle time of the boiler circuit and heating system, it should be filled with prepared water with a temperature not exceeding 40°C.
The water used to fill and feed the heating system should have a total hardness of no more than 1.5 mg-eq/dm³. The use of hard water leads to scale deposits in the system, a decrease in heat engineering parameters, and the destruction of the boiler heat exchanger.
Check the boiler and connected heating systems for strength and tightness with a test pressure equal to 1.25 of the working pressure.
The water pressure in the boiler circuit connected to a closed heating/district heating system should be at least 1 bar (0.1 MPa).
The water flow rate in the boiler circuit should correspond to its capacity with a temperature difference of 20°C. The circulation pump should be switched on before igniting the boiler.
Clean the internal surfaces of the combustion chamber, baffles, and ash pan from ash and soot.
Check the draught by lifting a strip of paper to the air supply damper.
Check if the air inlet opening in the boiler room is open.
Ventilate the boiler room for 10-15 minutes.

Initial startup and kindling

Attention! Using liquid fuels to kindle a solid fuel boiler is prohibited!

1 Place dry small chips of wood on a piece of paper through the loading door and open the damper on the chimney. Close the loading door and light the paper and chips through the ash door. Close the ash door and fully open the air damper.

2 Place a small layer of larger pieces of wood on the burning chips through the loading door. Wait until the larger logs ignite well and add the main fuel evenly to the full depth of the combustion chamber up to the lower edge of the loading door.

During the boiler heating, steam may condense from the outgoing gases and flow down the inner walls of the combustion chamber, giving the impression that the boiler is leaking. As soon as the water temperature at the inlet to the boiler exceeds 60°C, the condensation will stop.

3 Adjust the mechanical draft regulator as described below.

4 To prevent the coal from clumping together, it is recommended to first heat the water in the boiler with wood to a temperature of at least 60°C and then start loading the coal. Gradually and evenly load enough coal to form a layer about 50-60 mm high, then stop loading for 15-20 minutes to ignite the fuel. After closing the loading door, open the air damper.

Once the first layer of main fuel (about 2/3 of the loaded amount) has ignited, new fuel can be added on top of the unburned layer. To operate the boiler in nominal mode, the fuel layer should be maintained at a height of about 150-250 mm above the tubes.

As the fuel burns in the boiler, it should be reloaded with an even layer throughout the depth of the combustion chamber.

5 If the flame turns dark red, increase the draft by opening the air supply damper or the damper in the chimney. After the flame turns yellow, cover the air supply damper.

Adjust the air supply until the flame turns straw color with orange tongues. Always monitor the flame in the firebox, as flames with smoke and smoldering fires lead to inefficient fuel combustion and soot formation in the chimney.

6 The boiler's power can be changed using the damper on the smoke outlet pipe. To increase the temperature, open the damper and set the draft control handle to a higher temperature. To decrease the temperature, partially close the damper and set the draft control handle to a lower temperature.

The boiler's power can also be adjusted by fuel loading: large chunks and a small amount of fuel produce low power, while small pieces with a large amount of fuel produce high power.

7 During prolonged burning, the grate should be periodically cleaned to prevent a layer of hardened ash from blocking the air supply for combustion.

8 To stop the boiler, wait until the fuel is completely burned or stop the air supply to the solid fuel boiler by closing the air damper.

If an emergency stop of the solid fuel boiler is necessary, carefully open the loading door, remove the burning fuel from the firebox with additional tools, and extinguish the removed fuel with water.

Adjusting the Draft Regulator of a Solid Fuel Boiler

1 Heat the boiler to a temperature of 80°C.

2 Set the adjustment knob on the draft regulator to the temperature indicated by the boiler thermometer.

3 Adjust the chain on the air damper so that the position of the damper ensures that the boiler reaches the necessary temperature. The gap between the air damper and the boiler body should change within 2 to 50 mm.

4 Check the draft regulator at a different temperature. To do this, adjust the setting temperature to 90°C and check if the regulator maintains this temperature. When the temperature at the boiler outlet reaches 95°C, the regulator should close the air damper to a minimum gap of 2-5 mm (depending on the manufacturer's recommendations). If there is a limiting bolt in the boiler design that blocks further closing of the damper, adjust the gap with it.

5 After calibrating the draft regulator, set the required water temperature at the boiler outlet, recommended at 85°C.

Important! Low water temperature at the outlet of a solid fuel boiler may cause resin formation in the combustion chamber and soot deposits, which can result in blockage of the chimney. Try to maintain the temperature at the boiler outlet between 80-90°C.

Important! Operating the boiler with a temperature below 65°C or high moisture content of the fuel can result in condensate in the form of black liquid appearing from the boiler door due to the condensation of vapors on the heated surfaces.

Important! Complete closure of the air damper will result in incomplete combustion and formation of resin on heated surfaces.

Important! Do not leave the loading door open during combustion in the combustion chamber to avoid combustion products entering the room. Before opening the loading door, open the boiler damper!