How to identify and fix common eraser issues (2023)

Picture this: It's a cold winter night, so you decide to light a fire in your fireplace and curl up under a blanket, only to find that your entire house fills with smoke. It's not a very pretty picture, and it's certainly not what you expect from your fireplace.

A fireplace that fills your home with smoke is not only a nuisance, it can also pose a safety hazard. Below are many common reasons why you might be smoking in your home, how to identify the cause of your problem, and how to fix it.

closed damper

The most likely reason why your house fills with smoke when you start a fire is because thesilenceit is closed. The damper must be fully open when the fireplace is in use and closed when not.

All indoor fireplaces have a damper that must be opened before lighting a fire in your fireplace. An enclosed damper blocks the chimney to keep rain and debris out of your home and to keep conditioned (i.e. heated or cooled) air inside. If the damper is closed while the fire is lit, the smoke is blocked from going up the chimney and has nowhere to go but back into your house.

Your damper is in one of two places: in the chimney throat or at the top of the chimney. How your shock works depends on the type you have.

neck pillow

Most mutes are cast iron neck mutes. This type of hatch is a metal door located just above the firebox at the bottom of the smoke chamber. You can easily check if it's open or closed by looking into the fireplace with a flashlight.

Cast iron throat latches open and close with a handle attached to the latch door. To open the damper, simply lift the handle, push it all the way forward and pull to lock it in place.

If you forget to open the lid before lighting the fire, be careful when opening it, as the hot metal lid can cause severe burns. We recommend using a fireplace tool to safely open the damper while the fire is burning in the fireplace.

Top seal damper

The other type of shock you can have is a top seal shock. These flaps are located at the top of your chimney and very close to the chimney. They are opened and closed by a stainless steel cable or chain that runs down the chimney to a loop on the inside of the chimney.

chimney clogging

If your damper is open and smoke is still coming into your home, you may have a clogged chimney. These can take different forms.

creosote structure

If you have a wood burning fireplace, one of the most common and dangerous chimney clogs is creosote. When wood burns slowly, tar and other organic vapors are produced, which combine with expelled moisture to form creosote. Creosote vapors condense during cooling, while combustion by-products rise up the chimney. This condensed creosote can build up on the chimney lining.

We recommend having your chimney and chimney checked by a professional once a year (prior to the heating season) for creosote buildup. If a significant layer of creosote (1/8 inch or more) builds up, it should be removed to reduce the risk of chimney fire.

Bird nests and animal padlocks.

Creatures such as squirrels, birds and bats have been known to live in chimneys. Their nests and debris can build up over time, leading to clogging issues. Cobwebs in fireplaces that haven't been used for a long time can also redirect airflow.

If all you have are animal nests and debris, contact a professional sweeper who can safely and effectively remove the clog. If you have live animals that are causing the clog, do not light the fire until they have been removed by an exterminator.

Very small chimney caps or chimney caps

Many fireplaces come with a chimney cap or achimney. This accessory is both decorative and practical, helping to keep rain and dirt out of the fireplace.

A chimney that is too small or a chimney that is too small can allow smoke to re-enter your home. The base of the chimney cap or cap is often placed over the top of the chimney, but it should never be lower than the chimney. The chimney top should not be much narrower than the chimney itself; "reducing" the diameter can cause problems with smoke evacuation.

In general, caps and covers should have a combined opening that is four times the cross-sectional area of ​​the chimney. If your chimney or chimney top is too small, consider replacing it with a large unit to alleviate some of your smoking issues. to relieve.

differential pressure

A well-functioning house has near-neutral indoor air pressure and will work to maintain the natural pressure. When fire burns in a fireplace, the fire draws a huge amount of air up the chimney. To maintain the neutral pressure in the house, the air coming out of the chimney must be replaced with new "extra air".

When smoke comes back into your home, it usually means there is a downdraft and the room has a lot of negative pressure. In other words, the easiest way for supplemental air to replace lost or depleted air elsewhere in the house is toLowthe chimney.

A simple way to test whether the pressure difference is causing smoke evacuation problems is to hold a burning incense stick in the chimney throat. If smoke is rising up the chimney, the pressure difference is not your fault and you can move on.

However, if the smoke from your incense goes down and back into the room, it means your chimney has a downdraft. To solve this problem, you need to find a way to counteract the downdraft. You can do this by opening a window or door at the back of the house, turning off a fan or stove, or closing windows above. Test these things one at a time (while still using the incense for testing) and give the air enough time (2-3 minutes) to invert. See what it takes to control the indoor air pressure so there is no downdraft in the chimney and smoke starts to rise.

Keep in mind that every house is different. What works for one may not work for everyone. A good rule of thumb is to think about reducing the exhaust air in the upper part of the house and increasing the air entering the house on the lower floors. Remember that it can make a difference which window you open or close, especially if there's a breeze; if you open a window, make sure that outside air enters.

After controlling the pressure, you need to prove that you have adequate airflow for the fire.

enough air flow

Modern homes tend to be very airtight (think spray foam insulation, house wrap, weatherproof windows, etc.) to easily enter the house, meaning there isn't enough fresh air in the house for the chimney to enter. correctly.

To test whether airflow is causing smoke problems, you need to simulate air loss caused by a fire; this can be done by turning on a kitchen fan to create a downdraft. After turning on the fan, use the lit incense again to see where the smoke is going.

Then add ventilation air (open a downstairs window that blows air into the house, etc., as described above) until the fireplace cools down, even with the kitchen fan on. By going through this process, you can determine how much air is needed for the fireplace.

While the amount of combustion air needed will vary depending on the type of home, hearth, and fire size, a general rule of thumb is 1 cubic foot of fresh air per minute per 1 square inch of vent area.

Of course, opening a window every time you want to start a fire isn't an ideal long-term solution for all homeowners. For a permanent solution, you can install one of the following:

• Powered compensated air system (fan operated) connected to HVAC system (requires motorized damper)
• Compensated air kit connected to exhaust system (connected to pressure regulator)
• kaminventilator

wetter

Since the fireplace chimney extends along the roofline and out of the house, outdoor weather conditions can sometimes cause the house to fill with smoke. Two of the most common weather culprits are extreme cold and lateral drafts.

extremely cold

In very cold temperatures, an unused chimney can fill with high-density cold air, which in turn blocks the flow of smoke through the chimney. This is especially true if the fireplace is outside the house. In such cases, take steps to "warm" the fireplace by lighting a small newspaper fire at the back of the firebox. Keep inserting newspaper until smoke from the fire clears the chimney.

*Note: A brick fireplace will take much longer to "warm up" than a metal fireplace.

Side wind or distortion

Wind can cause smoke problems in several ways. The first form is known as dynamic wind loading. This occurs when the wind blows from one side of the house, creating an area of ​​high pressure on that side of the house and a corresponding area of ​​low pressure on the other side of the house. This creates a pressure difference which can be resolved by opening a window on the windward side of the house. For a more permanent solution, consider tightening the leeward side of the house (negative pressure side) and installing an outside air kit.

Wind can also create turbulence at the top of a chimney, preventing smoke from escaping, or it can even push smoke back up and down the chimney. This is especially common when there are high ceilings or trees nearby. You can fix this by replacing your raincoat with a protective cover.

chimney effect

The stack effect describes the movement of air into and out of buildings, chimneys, chimneys, etc. In most homes, there is usually a neutral pressure level halfway between the ground floor and the ceiling, which means that anything above that level is pressurized (air flowing in) and anything below it is under negative pressure (air flowing in). goes into).

In older houses, and generally in tall houses, the negative pressure rarely exceeds 8 pascals, which is approximately a 10-foot pressure difference. the height. Furnaces and chimneys generally pull well against a negative pressure of up to 8 pascals.

However, modern homes tend to be more densely built, using spray foam insulation, caulked windows and sealed doors. They are also often packaged with powerful exhaust fans for the kitchen and bathroom, so the neutral pressure level in the house may be higher (if it exists at all). As a result, negative pressure in the lower areas of the house can exceed 8 pascals and cause a draft in a chimney.

You can help reduce the chimney effect in your home by stopping air leaks in the highest parts of your home, including attic access hatches, overhead lights, and ill-fitting windows. However, you can't really change kitchen and bathroom exhaust fans that blow air out of the house. In this case, the chimney effect can only be corrected by introducing as much air into the house as is expelled from the house, that is, opening a window or adding a set of outside air.

bad building practices

If you've followed all of the troubleshooting tips above and nothing has stopped the smoke from flowing back into your home, your chimney may not have been designed correctly.

Schornsteinhöhe

When a house is taller than the chimney, the house has a "more effective chimney" and can function as a better chimney than the chimney itself, pulling air up the chimney and pushing it through cracks/leaks higher in the house . Pile height can also create a downdraft situation if the pile does not extend far enough into low density air to create a surrounding updraft. In general, a taller chimney tends to suck better.

If your chimney smokes because it's too short, the problem is likely to get worse when the wind blows. A chimney that is too short will not only not ventilate properly, but it can also present a serious fire hazard and fire hazard on your roof.

While not universal, we recommend following the 2-10-3 rule: A chimney should be 2 feet tall. taller than any structure within 10 feet and is 3 feet higher than the point where it penetrates the roofline. However, if you are building a fireplace, we always recommend consulting a professional and checking local building codes.

Very narrow throat or smoke box

A throat or smokebox that is too narrow for the size of the furnace will cause smoke draft problems. The throat at the front and back must fit snugly over the top of the firebox and not restrict the air space being opened. If you have a neck pillow, make sure it doesn't restrict the neck opening either. Check to see if chamotte bricks or other material has been added to the back of the throat that would reduce the throat opening area and must be removed. Look for smooth, streamlined surfaces with no obstructions to restrict or redirect airflow.

Inappropriate deduction size

For a fireplace to work well, you need to ensure that the size of the fireplace is adequate for the amount of smoke that can be produced in the firebox. A good rule of thumb is that the chimney opening should not be more than 10-12 times the chimney area. A smaller fireplace simply cannot handle the amount of smoke that causes something to blow back into your home. For metal chimney systems, we recommend at least a 14" chimney for 36" and larger boxes.

The chimney size must comply with the furnace size in accordance with Section R1003.15.1 or R1003.15.2 (IRC 2015).

• Square chimneys: 10:1 ratio (or every 10 square inches of chimney opening requires 1 square inch of chimney)
• Round trains - 12:1 ratio
• Rectangular (aspect ratio 2:1 or more) - aspect ratio 8:1

However, there are some exceptions to this rule.

• See-through fireplace: two openings = twice the size of the fireplace is needed (most manufacturers require glass doors on one side to solve this)
• Large units: 2 deductions are recommended
• Rumford fireplaces: 48 inches and larger have a draft risk and require a taller chimney height

And remember, bigger is not always better. Your fireplace must be the right size for your fireplace. If a fireplace is very large, the amount of heat produced by a small fire may not be enough to generate draft.

competing fireplaces

A house with multiple chimneys sharing a chimney can carry smoke if one is burning and the other is not, causing smoke to flow back into the house.

When you light a fire in a fireplace, you create negative pressure in the house. If the house is fairly airtight, the easiest way for the fire to get air is through the open chimney of the other hearth; that is, the smoke rises through the chimney and is sucked in through the other chimney along with the necessary fresh air. .

To fix this, you can increase the chimney height, which will make one chimney taller than the other. This allows smoke to escape without being pulled down by cold air. A height difference of at least 8 to 12 inches is recommended. If elevating the chimney isn't an option, you might also consider adding an outside air kit (also called a fresh air kit) to the smoke-causing chimney.

resume

Smoke spills can be caused by a variety of different factors, some easier to fix than others. The most common causes of smoke entering the home are:

• Chimney volume - diameter and height
• differential pressure
• air flow
• Obstacles (check the shock absorbers!)
• Vento

However, this list is not, and cannot be, exhaustive of all possible scenarios; other possible influences include:

• rack placement
• unseasoned firewood
• exhaust fans
• Height
• Tall trees near the roof line

If you have a chimney that is filling your home with smoke and you cannot determine the cause or you are not comfortable doing it yourself, seek the help of a licensed professional who can help you identify the problem and come up with a workable solution. long-term. offer. term - short term solutions.