Installing a draft regulator on a solid fuel boiler

The non-volatile draft regulator for solid fuel boilers is a device for coordinating the power of the unit. The mechanical device acts like a fan, has less accuracy, but does not require an electrical connection and is less expensive. The regulator in autonomous mode changes the volume of the supplied air flow by opening the damper.

Purpose and principle of operation of the draft regulator

The mechanical device does not provide high reliability, but it eliminates the manual control of the boiler power and saves coal and firewood. The amount of oxygen entering the furnace affects the intensity of the flame. Combustion is controlled by closing or opening a door in the chamber.

A thermomechanical device automates control over the process in accordance with the algorithm:

• When solid fuel burns, the energy carrier heats up, the liquid in the working capsule expands and acts on the working mechanism, overcoming the elasticity of the spring coil.
• The lever relaxes the chain, the door closes and reduces the air flow, which slows down combustion and starts smoldering.
• After cooling, the volume of the coolant decreases, the spring tightens the operating lever and the damper opens slightly.
• The process is repeated cyclically until the coal or wood is completely burned, then the spring releases the damper to the open position.

The regulator stabilizes the draft of the fresh air flow and prevents overheating of the heat exchanger. The device regulates the pressure in the heating system and makes the operation of the boiler independent of weather conditions. The mechanical installation dries the chimney from condensate when the unit is not heated.

Draft regulator design for solid fuel boilers

The flame intensity in boilers without any thermostat is changed manually by closing or opening the ash pan flap. Oxygen enters the combustion chamber due to the direct draft of the chimney. A mechanical device does the job for a person if the regulator is properly adjusted. At the first start-up of the unit, the size of the chain is selected between the lever and the point of attachment to the damper.

The structure of the mechanism differs from manufacturer to manufacturer, but the main elements are present in all models:

• built-in capsule-shaped thermostat;
• plastic head with 2 scales;
• immersion sleeve;
• stock;
• drive mechanism;
• spiral spring;
• chain;
• adjustment knob.

The main part is an automatic thermal element to ensure a uniform temperature. The link is placed in a cylindrical box and coordinates the movement of the ash pan door by means of a chain and a lever. The threaded body is inserted into the sleeve of the water shell, which is in contact with the energy carrier.

The sealed flask contains a liquid that is sensitive to temperature changes and expands strongly when exposed to heat. With the help of the handle on the pediment of the thermostat, the possibility of the movement of the lever and the damper is limited, the heating of the energy carrier is set.

Specifications

The planned operating temperature of the heating unit is included in the setting range with a margin in two directions.The connecting thread on the mechanical regulator must correspond to the parameter of the turns at the point of connection with the boiler. The weight of the damper should not exceed the lifting force of the lever, otherwise the door will not move from its place, in which case the support part is selected with great effort.

Mechanism characteristics:

• the body is made of all-metal chrome-plated brass;
• the handle is made of resin with a high temperature resistance;
• the chain is made of galvanized metal;
• a highly sensitive wax thermoelement is used;
• the temperature is set in the range of +30 - + 100 ° С;
• connecting chain up to 1.2 m long;
• useful chain force is 0.85 - 1.2 kg;
• the arm has a length of 0.12 - 0.14 m;
• angle of rotation of the lever 100 - 150 °;
• connects to unit with ¾ ”tapered thread;
• maximum water temperature +120 - + 130 ° С.

The regulator controls the temperature with a minimum error. The draft in the chimney maintains uniformity, regardless of wind loads, the heating of the structural elements of the heating unit is stabilized.

Recommendations for choosing a device

There are boilers on sale that do not have any draft control devices. In them, the automation is represented only by a sleeve, which is installed inside a water shell. The draft regulator is a necessary device, it is purchased and installed with your own hands. When buying a heating unit, attention is paid to the presence of such a sleeve and an ash pan door that can open upwards.

When choosing, take into account the parameters:

• initial and boundary adjustment temperature;
• correspondence of the connecting thread;
• lifting force;
• chain size;
• the range of movement of the lever.

The actuator travel must be able to fully open and close the damper. The position of the sleeve in the body matters. If it is at the top, the draft regulator for the boiler working vertically is selected. When the sleeve is located on the side or in front of the body, a mechanism is purchased that stabilizes the thrust in the horizontal direction. There are devices that work in two directions and include 2 numerical scales in the design.

Draft regulator installation and calibration

Installation according to the instructions is carried out when the coolant is drained in the heating system. The lever is detached and the adjusting mechanism is threaded into the seat. For packing the threads, seals in the form of threads, tow, and other similar materials are used; fum tape is used. The direction of the tip on the actuator is determined in accordance with the diagram in the technical data sheet, the lever is built in and fixed with a screw.

In the horizontal position, the fastener is at the top and the heating reading is indicated by a red scale. For vertical mounting, the screw is placed at the back and the temperature is read on a yellow scale.

The setting is carried out on a running heating unit at a temperature of + 60 ° C:

• the chain is inserted into the hole of the lever body, but is not attached to the damper, the door is placed in an open position for oxygen access;
• the fixing screw is loosened on the coordinating handle;
• the required temperature is set on the scale;
• the chain is connected to the damper at the moment when the set temperature is reached.

The correctness of operation is checked after calibration in all operating modes of the boiler, up to the limit power. If necessary, the chain is shifted by 1–2 rings to one side, for example, with readings below the norm, the connecting element is shortened, and in the opposite case, it is weakened. The rate of change is influenced by the volume and type of fuel, the inertia of the system and the unit.