How Chimneys Work
- Heat: the hotter the gases in the chimney compared to the air outside, the stronger the draft.
- Height: the taller the chimney, the more draft it will produce at a given temperature difference.
What is the purpose of a draft on a gas fireplace?
The draft is an important aspect of any fireplace that uses a real flame to generate heat, such as open wood burning fireplaces, gas fireplace and wood burning stoves. The draft helps to remove any smoke and harmful particulates from a fire from your home by sucking them out through the chimney or flue.
What is draft in a chimney?
This movement of combustion air and exhaust is called draft. In essence, it is the difference in pressure between the air/gasses inside the chimney flue and the outside air that creates this movement.
How does a gas fireplace work simple?
How Fireplaces Work. The most important mechanical function of a fireplace is to generate a draft. If you think of a hot air balloon, you know that a mass of heated air rises. A fireplace creates a column of heated gas inside the chimney. As that air rises, more heated air from the fire is pulled after it.
What is a draft stopper for a fireplace?
A fireplace draft stopper can come in a range of forms, but its main purpose is to block the movement of air up or down your chimney to help prevent cold drafts.
What creates a draw in a fireplace?
For a fireplace to draw well, you need to be sure the flue size is adequate for the amount of smoke that can be created in the firebox. A good rule of thumb is that the fireplace opening be no more than 10-12x the area of the flue.
How does a fireplace draw air?
A fireplace creates a column of heated gas inside the chimney. As that air rises, more heated air from the fire is pulled after it. The result is a draft -- a steady flow of smoke and hot gases -- up the chimney. The draft serves another purpose, too.
How do you stop a draft from a fireplace?
A fireplace draft stopper is an efficient way to prevent this from happening. Whether you use a chimney balloon, a fabric draft blocker, glass doors or even create your own decorative cover, a fireplace draft stopper will keep your home warm while lowering energy costs.
What causes a fireplace not to draw?
Chimney needs to be cleaned: Creosote build up in the chimney can reduce the the flow of exhaust gasses which can cause fireplace smoke and may also lead to a chimney fire. A shattered chimney flue can also cause drafting problems. Hire a chimney sweep to inspect your fireplace for damage and have the flue cleaned.
Should I crack a window when using fireplace?
Our #1 tip is to crack a window on the same level (or below) as the fireplace — basement windows work best. When you open the window, make sure that you feel the cold air blowing in.
Can a fireplace suck the oxygen out of a house?
The fire in the fireplace quickly consumes all the oxygen in the small area dedicated for the flame, Pruner said. After that, the fire sucks in oxygen from the rest of the house, often creating a draft to pull in air through cracks, power outlet covers and other openings.
Why is my fireplace so drafty?
What Causes a Drafty Fireplace? When there isn't a fire in the the fireplace, then the fireplace and chimney are just another opening to the out doors. Both indoor and cold outside air will flow in the direction of high-pressure moving to low-pressure.
Do fireplaces make house colder?
The standard fireplace is among the most inefficient heating devices you can operate. In fact, it can be so inefficient that in some cases it actually makes your house colder.
Do chimneys let in cold air?
The throat damper is a standard fixture in most chimneys. But its location just above the fireplace allows cold air to flow down much of the chimney even when shut. And although the damper is closed, warping or rusting can break its airtight seal enabling cold air to enter the fireplace.
How do you check a chimney draft?
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Do taller chimney draw better?
Taller Chimneys Produce Stronger Draft If draft problems are experienced with short systems, consider adding to the chimney height. If draft problems are experienced with systems higher than the recommended minimum system height, adding to the chimney may have little or no effect.
Does a chimney cap help draft?
Chimney caps with baffles can improve chimney draft no matter from what direction or speed the wind approaches the chimney. This type of chimney cap has a design that consistently creates a driving pressure at the top of the chimney to help pull the byproducts of combustion out of your chimney and home.
Does a fireplace need a fresh air vent?
Fire requires oxygen, so any fireplace with real fire from a source such as wood or gas requires a renewable supply of incoming air. This is often referred to as “fresh air,” though the IRC also calls it “combustion air.”
When should I close my fireplace vents?
You should close the damper on your fireplace once the fire and embers have all burned out. This prevents warm air in your house from escaping out the chimney. You should open the damper before lighting a fire and close it once the fire is done burning.
How does a fireplace get oxygen?
Many fireplaces take oxygen directly from inside the home. This causes a wide range of problems, but fortunately, they can be solved by installing an outdoor air kit to funnel in outside air for combustion.
Can you get carbon monoxide poisoning from a fireplace?
Yes, gas fireplaces are one potential cause of carbon monoxide poisoning. While there are many potential sources of such exposure, including certain appliances and devices, motor vehicles and wood stoves, gas fireplaces are a common culprit.
Why Is There A Draft From My Fireplace?
Traditional open fireplaces with chimneys use a process known as the draft to help remove smoke and other byproducts from a fire to leave your home.
Why is draft important in a fireplace?
The draft is an important aspect of any fireplace that uses a real flame to generate heat, such as open wood burning fireplaces, gas fireplace and wood burning stoves. The draft helps to remove any smoke and harmful particulates from a fire from your home by sucking them out through the chimney or flue.
What is the best plug for a fireplace?
A chimney balloon can be a good choice if your fireplace doesn’t have a damper. A chimney draft excluder is another form of plug for your fireplace that is also useful if there’s no form of damper in your chimney.
What is a chimney damper?
A chimney balloon is simply a form of balloon that you can blow up within your chimney to provide a tight seal.
How to keep cold draft out of fireplace?
One of the solutions to help keep a cold draft out of your fireplace is using a draft stopper (also known as a fireplace or chimney draft excluder, plug, blocker or cover) to block up the chimney and help prevent the movement of air that is generating these cold drafts.
How to stop cold drafts from coming down chimney?
In order to help prevent cold drafts from coming down your chimney you’ll need to consider blocking off the fireplace from the chimney. By blocking off the chimney you can help prevent air from moving through the fireplace, whether it’s losing hot air out of your home or letting colder air into it.
Why block off a chimney?
Warmer air to be lost up the chimney. As this can be a common issue with many homes, there are therefore a number of ways to help block off a chimney between fires so that you’re not feeling a cold draft from the fireplace and not losing warm air from your home at an increased rate.
What is the most important aspect of a fireplace?
The single most important aspect of any fireplace, inside or outside, is its functionality and whether the smoke rises effectively. This will be either through the chimney or out the front of the firebox and up the front of the structure.
How to know if your outdoor fireplace is bad?
Pay attention to the inside of outdoor fireplaces that you see around your town. Stick your head inside and look up. Do you see a tiny chimney opening, or a large opening that will collect the smoke before allowing it to evacuate upward? Most of the time, there will be very apparent issues with regard to the path of least resistance. When a firebox height in is equal to the chimney opening, you will have problems with a bad draft.
How to get smoke out of a gas fireplace?
The smoke or invisible soot from a gas burn will exit the structure through the front when draft is affected. This smoke and/or soot will travel right up the front of the structure and the front will turn black. A wet rag and some dish soap can easily remove the soot from a fireplace. It’s just a hassle to deal with.
Is a gas fireplace good or bad?
Gas Fireplaces – The Good and Bad. A lot of fireplaces are designed and plumbed to burn natural gas or propane. Gas fireplaces are easily controlled and can be turned on and off quickly. This can also be problematic if the structure isn’t built correctly.
Can a gas fireplace cause soot?
Even with a gas fireplace, burning either natural gas or propane, which are very popular, soot build up can still be a problem. This occurs if the fireplace does not vent well. Heat rise in a fireplace is most often referred to as the draft.
How does chimney draft affect pressure?
Since draft is a measure of pressure, chimney draft is affected by pressure conditions in the house. Several factors come into play: Adequate air. First, there must be adequate air movement into the house to make up for the air exiting through the chimney.
What causes the air in a chimney to move upward?
In essence, it is the difference in pressure between the air/gasses inside the chimney flue and the outside air that creates this movement. Warmer, lighter gasses in the flue tend to move upward.
Why does my house have a stack effect?
Open windows upstairs are just one cause. A poorly-insulated roof, a drafty attic, a tall stairwell, or anything else that allows a considerable amount of heated air to exit the house upstairs could create a stack effect problem.
What is the purpose of a chimney?
The purpose of a chimney is to take the combustion products (smoke and gasses) from the appliance to the atmosphere outside your home, and at the same time, to draw air for combustion into the appliance. This movement of combustion air and exhaust is called draft.
Can chimney draft be complicated?
Since the chimney draft is affected by so many factors, draft problems can be complicated . We will cover diagnosis and correction of draft problems in the sections on fireplaces and stoves.
How does increasing the amount of gas in a fireplace affect the heat?
Increasing the amount of gas getting to the burner increases the size of the flames and therefore increases the amount of heat a gas fireplace is generating.
What is the main part of a gas fireplace?
One of the main parts inside a gas fireplace is the ignition system .
What is standing pilot ignition?
Standing pilot ignition is the more traditional version where the pilot flame remains constantly on, even between fires, albeit typically turned off when the fireplace isn’t used for an extended period of time such as through summer.
What is the ignition system for a pilot flame?
Starting the pilot flame using an ignition system that typically consists of a pilot, a spark ignitor, and a thermocouple and/or thermopile.
What is the difference between a pilot light and a burner?
The main burner flames are the flames you see in a gas fireplace, while the pilot light is a small flame typically tucked away out of view.
Why use faux fireplace media?
The whole fireplace experience is therefore enhanced by using a set of faux fireplace media to help make the fire look more realistic.
When does the pilot flame go off?
For gas fireplace that use the electronic intermittent polit ignition, the pilot flame with go off when the main burner flames are turned off.
Why does my chimney have drafts?
Quite often, chimney draft failures are caused by wind, blowing down or across the top of the chimney. If the problem only occurs when the wind blows, replace your rain cap with a draft inducing cap that works on Bernouli’s principle, such as the old-fashioned “roostertail”, or the more effective Vacu-Stack. These caps are designed to reverse the effects of wind-induced downdraft or crossdraft, but will only work when the wind is blowing directly onto them. Draft inducing caps will not correct a downdraft caused by increased air density at the top of the chimney due to air inversion, or the type of chimney-top pressurization which can occur when the wind blows across the top of a cylinder formed by nearby tall trees, hills, or buildings that extend above and totally surround the chimney.
Why is there an ambient chimney draft?
Ambient chimney draft occurs because the top of the flue extends upward several feet, into a lower density atmosphere than exists at the bottom.
What can block a chimney flue?
Flue blockage. If the chimney is the proper size and still isn’t providing sufficient draft, the first thing to do is check the stovepipe and chimney flue for blockage: bird nests, fallen bricks, Frisbees, leaves, etc. can block or partially block a chimney flue, interfering with proper draft.
What happens if your chimney is too big?
If it is too big, it may draw too slowly for the appliance, and may never heat up enough to compensate. For this reason, both flue undersizing and flue oversizing should be avoided. If your chimney is too small, replace either the chimney or the appliance.
Why are masonry chimneys so hard to prime?
Masonry chimneys can be hard to prime, because masonry materials are terrible insulators: it would take a brick chimney with sidewalls 28″ thick to provide the same insulation as the one inch of insulating blanket used in today’s prefabricated insulated metal chimneys. A masonry chimney bleeds precious heat away from the exhaust and transmits it through to the outside of the flue, slowing the thermal updraft (and promoting creosote formation). Masonry chimneys that extend up through the house stay warmer than those that are exposed to outside temperatures for their entire length, but all chimneys lose precious flue temperature above the roofline.
What to do if your fireplace smokes?
If your fireplace smokes because the flue is too small, try temporarily reducing the size of the fireplace opening with pieces of sheet metal; if this works, use masonry materials or products such as the Smoke Guard to accomplish a permanent solution.
How to tell if chimney is inverted?
One way to tell if air inversion is causing temporary draft problems is to look at the smoke that exits the flue: if it eddies around the top of the chimney or flows downward onto the roof instead of rising as heated air normally would, an inversion layer is most likely present.
Why do you open the damper when you have a fire lit?
Because otherwise the fire can't get enough oxygen. Not necessarily! A fireplace fire can sustain itself without an open chimney above it. The reason to open the damper when you have a fire lit has to do with what comes out of a fire, not what goes into it.
How to keep a fireplace from burning?
Make sure your fire is completely out or else residual smoke could fill your home. When the embers are cold to the touch, pull the cord or lever to close the damper. Keep the damper closed when the fireplace is not in use. ...
What is a damper on a chimney?
Hire a professional to install a damper if you don’t have one. A damper rests inside of or on top of your chimney and prevents drafts from coming down the chimney. Since improper installation could result in a chimney fire or chimney blockage, hire a professional service.
What is a chimney balloon?
Chimney balloons are reusable and inflatable plastic pieces that fit inside your chimney to block any drafts. They are easy to use, but only if you have access to the interior of your chimney. Chimney balloons can be purchased from online retailers. Inflate the balloon partially so it resembles a floppy pillow.
How to make a balloon fit in a chimney?
Inflate the balloon partially so it resembles a floppy pillow. Blow air into the plastic tube attached to the handle of the balloon. A few breaths should be enough to spread the balloon out. This helps you work with the balloon so it fits easily into the chimney.
How big should a draft guard be?
Buy a guard that is at least 3 inches (7.6 cm) larger on each side of the hole so you have some wiggle room.
Do you have to remove a balloon before a fire?
Remove the balloon before you light a fire. The balloon needs to be removed before you start a fire so smoke or gas doesn’t fill your home. Chimney balloons have a fail-safe if you forget to remove them and will deflate when it’s heated.
