Providing draft in the chimney regardless of the weather and temperature in the house is a difficult task. In the off-season, when it is colder in the house than outside, the smoke stops rising through the chimney. The problem is solved either by mounting a fan in the chimney to improve draft, or by preheating the stove with hot air.
Agree, it is better to take care of the fan insert even at the stage of construction and installation of equipment than to face the lack of traction when there are severe frosts outside.
In this article we will tell you when you need to install a fan, and when you can do without it. We will also figure out how to install the device yourself.
The content of the article:
- Checking the operation of the chimney
- Inlet valve to increase traction
- When do you need to increase the chimney performance?
- Simple ways to increase traction
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Fan - advantages and disadvantages
- Requirements for the exhaust device
- Fan installation in the chimney
- Conclusions and useful video on the topic
Checking the operation of the chimney
The chimney works correctly if gases are removed from the premises to the outside. Reverse thrustwhen smoke enters the room from the chimney and stove - an extremely undesirable phenomenon.
Signs of poor traction are easy to spot:
- when the oven is operating, smoke enters the room;
- gusts of wind outside affect the movement of gases in the pipe, creating reversible direction. Pops are heard in the oven and ash pan;
- fuel is difficult to ignite;
- even dry wood burns slowly;
- opening a window, doors dramatically reduces traction.
It is more difficult to find out about the bad exhaust of the column or gas boiler. Carbon monoxide can enter the room, but it is difficult to feel or see it.
It is deadly to breathe in such gas.
To accurately determine the characteristics of the chimney, you can use an anemometer. It is used to measure the speed of movement of furnace gases.
It is widely believed that the quality of the hood's work is recognized by burning a match or a piece of paper. This method leads to an error and cannot be used. A match emits hundreds of times less smoke when burning than firewood in a fireplace, for example. The smoke from the match will go away, but this does not mean the complete removal of gases from operating devices.
The exact parameters of the chimney are determined using special equipment. Disregarding the roughness and length of the walls, the gas velocity 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 capacity of the furnace equipment, gas water heater and other devices. Most often, the readings of the device are in the range from 12 to 20 Pa.
Experts can determine the parameters smoke exhaustusing an anemometer. The device is compact, easy to use. They measure the speed of movement of gases. But you need to know the geometry of the passages, the cross-sectional area of the pipe.
Before measuring, you need to warm up the chimney and the stove. In winter, it is enough to heat a fireplace or use a gas water heater for an hour
The data obtained is verified with the requirements recorded in the passport of the gas or furnace equipment. If the volume of gas removal in one hour is insufficient, the equipment must not be operated.
Inlet valve to increase traction
Without air entering the room or directly into the stove, the chimney will not work. A vents or slots in old windows are not the best method for getting air in.
The disadvantages are obvious:
- Cold air enters the room through the cracks even when the stove or fireplace is not working.
- In winter, outdoor air constantly changes the indoor environment. At the same time, the relative humidity of the air drops sharply, which is harmful to health. A person's mucous membranes dry out, conditions for colds arise.
- The window must be opened and closed manually.
It is much more efficient to provide air flow by valve. It closes automatically when oven equipment or gas heaters are not working.
This is what a wall supply valve looks like, which is installed in rooms with stove heating or gas equipment to improve air flow
The heaters require a boiler room valve to operate. The device has other characteristics than similar structures for room ventilation.
The supply valve is placed diagonally or above a heated surface so that cold air rises to the ceiling. But it is best if oxygen is supplied directly to the furnace. At the same time, the humidity and temperature conditions in the room are not disturbed.
When do you need to increase the chimney performance?
Poor draft is not always the only reason for chimney work. It may be necessary to increase the rate of removal of carbon monoxide if additional equipment is connected to the hood from the stove.
It is allowed to use the chimney to connect the column if the equipment is on the same floor. And if the chimney is sufficient for operation gas heater volume margin smoke exhaust.
Another reason to increase chimney draft is to install a more powerful heater. The required parameters of the chimney are indicated in the passport data of the product.
It is also worth paying attention to how quickly it turns out to kindle a fire in the stove. For example, with low traction, raw wood will not burn
If the volumes of removed gases do not match the capabilities of the existing system, then the chimney needs to be modernized.
Simple ways to increase traction
Completely change the chimney as a last resort. It's worth starting with simpler methods.
First you need an old chimney clean off soot and dirt. Special metal brushes are used for this.
If during the construction phase the channels and the pipe 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 currents inside the chimney, when the air goes down along the cold wall, interfering with the upward currents.
Another effective way to increase traction is to reduce the number of bends in the smoke exhaust system. Partial rebuilding of the chimney is less expensive than a complete replacement of the system.
A popular way to increase chimney draft is to install a deflector. The wind becomes a helper, and does not create gusts of reverse thrust
You can also use a rotary turbine. During the wind, the turbine spins the impeller, which provides additional vacuum at the outlet of the chimney.
An equally effective way to increase traction 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
The exhaust fan can speed up the air flow by 3-7 times. At the same time, the volume of removed gases per unit of time increases by the same factor.
Besides:
- the active system allows you to simply and at minimal cost increase traction;
- 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 adjust the rate of smoke removal depending on the operating mode of the gas and furnace equipment. With a decrease in the power of the heaters, the fan speed is reduced.
Smoke removal requires a smaller duct cross-section due to the rapid air movement. This means that an active chimney requires less material to manufacture.
A modern chimney fan is protected from rain, leaves. It is installed on the pipe using special fasteners.
But there are also disadvantages:
- the fan is consuming energy. This increases the operating costs of the heating system;
- you need to lead a cable to the motor. This is not so easy to do. The active hood is placed on the pipe, and it is undesirable to make holes for the wire in the roof;
- it is necessary to provide protection measures against precipitation and icing of the impellers.
The listed disadvantages must be taken into account when switching to active smoke extraction. Then the cons can be neutralized.
Taking into account the positive properties of the active hood, the smoke exhauster is installed on the pipes of modern cottages, in houses, when installing fireplaces on wood or briquettes.
Requirements for the exhaust device
Not every impeller engine is suitable for carbon monoxide applications.
The smoke exhauster should be:
- Heat resistant. It should be borne in mind that when the stove or fireplace is in operation, 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 and more.
- Resistant to aggressive gases.
- Economical. In windy conditions, the electric motor is switched off. The impeller spins up as in a rotary turbine.
- Waterproof. Weather conditions should not prevent smoke exhaust.
- Effective. The fan must ensure the rapid removal of furnace gases at all temperatures outdoors and indoors.
A duct fan for smoke removal 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.
The chimney fan should not be confused with the forced draft in the fireplace. The latter is designed to ignite and maintain combustion in the furnace. While the blower fan is cut into the chimney, or the smoke exhauster is installed on the chimney. Modern devices for active removal of furnace gases withstand temperatures up to 600 ° C.
Active device smoke exhaust monitors 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.
Fan installation in the 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 securing safety elements
Next, mark on the pipe places for attaching the exhaust fan, and conduct a cable to power the engine. Lay signal wires from gas controllers and others energy devices.
In the following stages:
- Mount the fan assembly, eliminate cracks, check the tightness of the connections.
- Connect the power cable, connect the sensors to the wires.
- Power voltage is applied, the smoke exhauster is started.
- The parameters of the carbon monoxide removal system are checked with the help of measuring instruments.
- They complete the installation work, remove the fixtures from the roof.
- The sensors are connected to power plant control systems.
- Include gas appliances, stoves, fireplaces and re-check efficiency smoke exhaust.
For the operation of the smoke exhauster, installed on top, cable and wires are passed through the roof. This is not always convenient. If you do not need to install a product with a rotary turbine function, they buy a high-temperature duct fan to remove furnace gases.
The device is cut as far as possible from the place where the exhaust air is heated. The installation algorithm for the duct 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 is shown in the following video:
Active smoke exhaust provides hassle-free use of a fireplace and gas equipment at any time of the year. Even in summer, when the air temperature in the room is lower than outside, the fireplace will not smoke.
With the help of a fan, it is easiest to increase the draft, to exclude the reverse movement of the furnace gases. Considering that the forced exhaust for the chimney reduces the cost of manufacturing air ducts, it is used in modern systems smoke exhaust.
Perhaps you had to install a fan on your chimney yourself? Please tell our readers about it. What prompted you to install the smoke exhauster and what difficulties you had to face during installation. Leave your comments in the block below.
