Fan in the chimney to improve draft: types of devices and instructions for inserting

Ensuring draft in the chimney regardless of the weather and temperature in the house is a difficult task.In the off-season, when the house is colder than outside, smoke stops rising through the chimney. The problem can be solved either by installing a fan in the chimney to improve draft, or by preheating the stove with hot air.

Agree, it is better to take care of installing a fan at the stage of construction and installation of equipment than to face a lack of draft when it is severely frosty outside.

In this article we will tell you when it is necessary to install a fan, and when you can do without installing it. We’ll also figure out how to install the device yourself.

Checking the operation of the chimney

The chimney works correctly if the gases are removed from the room to the street. Backdraftwhen smoke enters the room from the chimney and stove - an extremely undesirable phenomenon.

Signs of poor traction are easy to spot:

• when the stove operates, smoke enters the room;
• gusts of wind outside affect the movement of gases in the pipe, creating reverse direction. Popping noises are heard in the stove and ash pan;
• fuel is difficult to ignite;
• even dry firewood burns slowly;
• opening the window or doors sharply reduces traction.

It is more difficult to find out about a bad hood of a water heater or gas boiler. Carbon monoxide can enter a room, but it is difficult to smell or see.

Breathing such gas is deadly.

To accurately determine the operating characteristics of the chimney, you can use an anemometer.It is used to measure the speed of movement of furnace gases

It is a common belief that the quality of a hood’s operation can be determined by the burning of a match or piece of paper. This method leads to an error and cannot be used. When burning, a match emits hundreds of times less smoke than wood in a fireplace, for example. The smoke from the match will go away, but this does not mean that the gases from the operating devices will be completely removed.

The exact parameters of the chimney are determined using special equipment. If you do not take into account the roughness and length of the walls, the speed of gas movement depends on the geometry of the channel and the pressure difference in the room and in the upper part of the pipe.

The gas flow must correspond to the power of the furnace equipment, gas water heater and other devices. Most often, the device readings range from 12 to 20 Pa.

Experts can determine the parameters smoke removalusing an anemometer. The device is compact and easy to use. They measure the speed of gas movement. But you need to know the geometry of the passages and the cross-sectional area of ​​the pipe.

Before measurements, you need to warm up the chimney and stove. In winter, it is enough to heat a fireplace or use a gas water heater for an hour

The data obtained is checked against the requirements recorded in the passport of the gas or stove equipment. If the volume of gas removal in one hour is insufficient, operation of the equipment is prohibited.

Inlet valve for increased draft

Without air entering the room or directly into the stove, the chimney will not work. Vents or cracks in old windows are not the best method for air flow.

The disadvantages are obvious:

1. Cold air enters the room through the cracks even when the stove or fireplace is not working.
2. In winter, air from the street constantly changes the indoor environment. At the same time, the relative humidity of the air drops sharply, which has a harmful effect on health. A person's mucous membranes dry out, creating conditions for colds.
3. The window must be opened and closed manually.

It is much more effective to provide air flow with valve. It closes automatically when furnace equipment or gas heaters are not operating.

This is what a wall supply valve looks like, which is installed in rooms with stove heating or gas equipment to improve air flow

Heaters require a boiler room valve to operate. The device has different characteristics than similar operating principles for room ventilation.

The supply valve is placed diagonally or above the heated surface so that the cold air rises to the ceiling. But it is best if oxygen is supplied directly to the firebox. At the same time, the humidity and temperature conditions in the room are not disturbed.

When is it necessary to increase the performance of a chimney?

Poor draft is not always the only reason for chimney work. It may be necessary to increase the rate of carbon monoxide removal if additional equipment is connected to the hood from the stove.

It is allowed to use a chimney to connect a column if the equipment is located on the same floor. And if the chimney is sufficient for operation gas heater volume reserve smoke removal.

Another reason to increase the draft in the chimney is to install a more powerful heater. The required parameters of the chimney are indicated in the product data sheet.

It is also worth paying attention to how quickly you can light a fire in the stove. For example, if the draft is weak, damp wood will not burn

If the volumes of gases removed do not match the capabilities of the existing system, then the chimney needs to be modernized.

Simple Ways to Increase Traction

As a last resort, completely replace the chimney. It's worth starting with simpler methods.

First you need an old chimney remove soot and dirt. Special metal brushes are used for this.

If at the construction stage the channels and pipes were not insulated, it is worth do it. Warm gases are removed more efficiently than cooled ones. In addition, it is necessary to exclude convective flows inside the chimney, when air flows down along the cold wall, interfering with the upward flows.

Another effective way to increase draft is to reduce the number of bends in the smoke removal system. Partial reconstruction of the chimney is cheaper than a complete replacement of the system.

A popular way to increase draft in a chimney is to install a deflector. The wind becomes a helper rather than creating gusts of reverse thrust

A rotary turbine can also be used. When there is wind, the turbine spins the impeller, which provides additional vacuum at the chimney outlet.

An equally effective way to increase draft is to increase the height of the chimney. The speed of movement of gases and, accordingly, the performance of the system as a whole depends on the height of the chimney.

We looked at passive ways to increase traction. But there is another effective method, which is discussed below.

Fan - advantages and disadvantages

An exhaust fan can speed up the air flow 3-7 times.At the same time, the volume of gases removed per unit of time increases by the same amount.

Besides:

• the active system allows you to increase traction simply and at minimal cost;
• The hood parameters do not depend on the weather. Does not affect the hood and indoor temperature;
• conditions for reverse thrust are excluded;
• it becomes possible to regulate the rate of smoke removal depending on the operating mode of gas and furnace equipment. When the heater power decreases, the fan speed is reduced.

To remove smoke, a smaller cross-section of air ducts is required due to rapid air movement. This means that an active chimney requires less material during manufacture.

A modern chimney fan is protected from rain and leaves. It is installed on the pipe using special fasteners

But there are also disadvantages:

• the fan consumes energy. Due to this, the operating costs of the heating system increase;
• You need to run a cable to the motor. This is not so easy to do. The active hood is placed on a pipe, and it is not advisable to make holes for the wire in the roof;
• It is necessary to provide measures to protect the impellers from precipitation and icing.

The listed disadvantages must be taken into account when moving to active smoke removal. Then the disadvantages can be neutralized.

Taking into account the positive properties of active exhaust hood, the smoke exhauster is installed on the chimneys of modern cottages, in houses, when installing fireplaces using wood or briquettes.

Requirements for the exhaust device

Not every engine with an impeller is suitable for working with carbon monoxide.

The smoke exhauster must be:

1. Heat resistant. It must be taken into account that when a stove or fireplace is operating, the smoke heats up much more than in the column.The temperature of gases from the fireplace at the outlet of the chimney can reach 300 °C or more.
2. Resistant to aggressive gases.
3. Economical. When there is wind, the electric motor turns off. The impeller spins as in a rotary turbine.
4. Water resistant. Weather conditions should not interfere smoke removal.
5. Effective. The fan must ensure rapid removal of furnace gases at any indoor and outdoor temperatures.

A duct fan for removing smoke is built into the air duct. But more often they use a smoke exhauster installed on a pipe.

The high-temperature duct fan must operate in an aggressive environment. Therefore, it is made from smoke-resistant materials

Do not confuse a chimney fan with a forced draft fan in a fireplace. The latter is designed to ignite and maintain combustion in the firebox. While the boost fan is cut into the chimney, or a smoke exhauster is installed on the pipe. Modern devices for active removal of furnace gases can withstand temperatures up to 600 °C.

Active device smoke removal controls the temperature of gases and their speed using sensors. The data is used to control the engine and ensure the safe operation of the fireplace, stove and gas equipment.

Installation of a fan in a chimney

Before installing the fan on the pipe, you need to carry out a number of preparatory work. The first step is to ensure safe working at height.

To do this, a special ladder is installed on the roof next to the pipe with the possibility of attaching safety elements

Next, mark the places on the pipe for attaching the smoke exhauster, and run a cable to power the engine. Lay signal wires from gas equipment controllers and others energy devices.

At the following stages:

• Mount the fan assembly, eliminate the gaps, and check the tightness of the connections.
• Connect the power cable, connect the sensors to the wires.
• Apply power voltage and start the smoke exhauster.
• Using measuring instruments, check the parameters of the carbon monoxide removal system.
• The installation work is completed and the fixtures are removed from the roof.
• Sensors are connected to power plant control systems.
• Turn on gas equipment, stoves, fireplaces and check efficiency again smoke removal.

To operate a top-mounted smoke exhauster, cables and wires are routed through the roof. This is not always convenient. If you do not need to install a product with the function of a rotary turbine, buy a high-temperature duct fan to remove furnace gases.

Install the device as far as possible from the place where the exhaust air is heated. The installation algorithm for a duct smoke exhauster does not differ from that discussed above.

Conclusions and useful video on the topic

Details on how to mount a fan on a chimney are shown in the following video:

Active smoke removal provides hassle-free use of fireplace and gas equipment at any time of the year. Even in summer, when the indoor temperature is lower than outside, the fireplace will not smoke.

Using a fan is the easiest way to increase draft and eliminate the reverse movement of furnace gases. Considering that forced exhaust for a chimney reduces the cost of manufacturing air ducts, it is used in modern systems smoke removal.

Perhaps you have had to install a chimney fan yourself? Please tell our readers about it.What prompted you to install a smoke exhauster and what difficulties did you encounter during installation? Leave your comments in the block below.