Tag Archives: flue

An open fireplace damper is like an open window

Chimney, Fireplace, , , , , ,

Money flying out of walletDuring these dog days of summer, many homeowners are making a very expensive mistake. Here in San Diego, homeowners are opening their SDG&E envelopes and getting sticker shock with astronomically high utility bills. What homeowners don’t realize is that by making a very simple change, they can save a great deal of money.

 

So here’s the tip: CLOSE YOUR FIREPLACE DAMPER!

What is a flue and what is a damper?

These terms are not interchangeable.

The flue is the vent pipe that allows gases, smoke, and heat to exhaust out of the home. The damper is a metal plate that opens and closes off the flue. When the fireplace is not in use, the damper should be closed in order to close off the flue.

Dampers are typically located at the bottom of the flue pipe, just above the firebox in the throat of the system.

Dampers typically have a rod or handle that you can push forward or backward. Other dampers move side to side, while others pull down or push up. It all depends on the type of fireplace you have.

In some cases, dampers can be located at the very top of the flue pipe with a chain that comes down and hooks in a bracket inside the firebox. These are called “top-mount” dampers. To close these dampers, you pull the chain down and hook it in the bracket. To open, you unhook the chain from the bracket and the damper plate pops open at the top because it’s spring activated.

Not all fireplaces have dampers but most do.

Why it’s important to close dampers

Here in San Diego, because our weather is typically very mild, many homeowners leave their dampers open all the time, not realizing that by doing so, their air conditioner is working overtime, costing the homeowner unnecessary money.

When the air conditioner is on and the damper is open, hot air from the outside is being drawn down the chimney and into the room. You’re actually sucking the hot air into your house. It totally defeats the whole purpose of using your air conditioner. In addition, if your chimney is dirty, you’re also sucking particulates of soot, which is a carcinogen, into the home. This is another reason to keep your chimney clean and your damper closed when the chimney is not in use.

It’s not just summertime that open dampers create problems. During winter time, when it’s cold outside, if your damper is open and you turn on your furnace, all you’re doing is sucking cold air into the home. This totally defeats the whole purpose of having your furnace turned on. So keep the damper closed during the winter time when you’re not using your fireplace.

How to tell if dampers are open

It’s not always easy to tell if your damper is open or closed. In fact, this is the #1 question when homeowners call me about their chimney. Unfortunately, because dampers open differently based on what type of system you have, I can’t give a conclusive answer over the phone. Here are several ways to tell if your throat damper is open or closed:

1) It’s actually easier to tell during the daytime than at night. One way you’re going to see more light from the sun than the other way. Keep in mind that because chimneys are not built straight up and down, you’ll rarely ever be able to see blue sky but one way you’ll be able to see more light than the other.

2) With a flashlight, look up from the firebox into the flue pipe. You should be able to see the metal damper plate in the throat of the system. When it’s open, you’ll actually feel more air movement than when it’s closed.

3) Light a match and blow it out. Immediately place the match close to the damper. The smoke from the blown-out match will indicate if the damper is open or closed.

4) Of course, there’s always the method that many homeowners use. Light the fire on a wing and a prayer. If it smokes out your house, then you know your damper is closed. We do not recommend this method due to the smoke damage to your home and to your lungs!

Here are examples of open and closed dampers.  This is looking from the firebox (where you make the fire) up the flue pipe:

Closed damper for masonry
Closed Damper for Masonry Chimney
Closed Damper for Pre-Fab Chimney
Open Damper for Masonry chimney
Open Damper for Masonry Chimney
Open Damper for Prefab Chimney

An Important Tip to Remember about Dampers

It’s not easy to remember, from season to season, which way the damper is open and which way is closed. To help me, I made a label and stuck it to the underside of the mantle which tells me which way to open. If I forget, I know where to look to find out easily.  Here’s the label I had on the underside of my own mantel:

Damper label

Not all dampers open this way so find out which way yours is open and make a label to place on the underside of your mantel.

Damper clamps

If your firebox is plumbed for gas, either for gas logs or a log lighter for burning with wood, then the damper has to be locked in a fully-open position with a clamp. You will not be able to close your damper. This is required by code in most areas of the United States. In this case, you may consider glass doors on the front of the fireplace.

Open window with curtainsRemember, an open damper is the same as an open window. Would you leave a window open when your air conditioning or furnace is on? Then why would you leave your fireplace damper open?

What is a Masonry Chimney?

Chimney, , , , , , , , , , , , , ,

A masonry chimney on the exterior wall of a home

Just like automobiles that have different manufacturers and models, the same goes for fireplaces and chimneys.

Here in Southern California, there are primarily three different types of open fireplace systems–1) masonry chimneys; 2) prefabricated, factory-built systems; and 3) Rampart General Pre-Cast systems. Since I’ve already addressed Rampart General Pre-Cast systems in the past, this post will be about the masonry chimney.

The History of the Masonry Chimney

These masonry systems have been around for many centuries and are tried and true. They are constructed on-site with bricks, stone, concrete blocks and mortar. Masonry systems are built by hand, brick by brick. If the system is built properly and maintained regularly and there are no extenuating events (such as earthquakes and wildfires), they will last a century or more. In fact, it’s not uncommon to see masonry chimneys still in use in houses built in the 18th and 19th centuries.

Unfortunately, due to the high cost of labor, these systems haven’t been constructed since the mid-1980s here in Southern California except for in high-end, custom-built homes.

For a fireplace to work properly, there is a formula involved in building a masonry chimney system. Some of the factors in this formula have to do with the height of the chimney, the diameter of the flue pipe, and the height/width of the firebox opening. If a system isn’t built properly, the chimney will never draw properly and will have ongoing smoking problems.

Components of a Masonry Chimney and Fireplace

It’s important to know the various components of a masonry chimney:

Flue cap – The chimney cap consists of spark arrestor material with a solid lid. It provides three primary benefits: 1) It prevents embers from getting on the roof; 2) It prevents birds, rodents and other critters from entering the home through the chimney; and 3) Flue caps with solid lids will also prevent most of the rain from coming down the flue lining. Without the solid flat lid of the cap, rain would land in the smoke shelf which may cause damage to the damper and may deteriorate the firebox.

Crown – The crown is a concrete or mortar surface at the very top of the chimney structure. Its purpose is to direct water Masonry chimney componentsaway from the structure. A crown can also be referred to as a “wash” or a “splay.” A cracked crown will allow moisture to get into the chimney structure, eventually creating cracks in the chimney structure.

Flue – The flue is the passageway from the firebox to the top of the chimney structure. In a masonry chimney, the flue is lined with a flue lining typically made from terra cotta, pumice or metal.

If the flue lining is cracked, broken or if the mortar joints are missing between the flue tiles, the system cannot be used because of heat transference or deadly carbon monoxide leaking into the house. There are three primary methods for repairing cracked flue linings–1) relining the system with a stainless steel pipe; 2) installing a stove insert with a metal pipe to the top of the chimney structure; or 3) a poured cement, cast-in-place system.

In addition, older systems may not have a flue lining at all (which is referred to as an “Unlined Chimney”). In this case, the system cannot be used until it has been repaired.

Flue tiles – A flue lining inside a flue is basically a vent pipe. This pipe is not one solid pipe. In most cases, the pipe (typically terra cotta or pumice) is made up of pipe sections called flue tiles. Each flue tile (pipe section) is anywhere from 12″ to 24″ tall. In between each flue tile is the mortar. There should not be any gaps or voids in the mortar joints.

Smoke Shelf – A horizontal shelf located behind the damper to prevent down drafts and to collect debris that has fallen down the chimney.

Damper – The device that opens and closes so that heat is not lost from the home when the fireplace is not in use. Some dampers can be installed at the top of the chimney flue.

Lintel – A horizontal metal piece that extends over the entire width of the firebox opening at the top of the firebox opening. It is a structural part of the firebox. Here’s important information on why you never want to remove a lintel.

Firebox – The area of the fireplace where the fire is burned.

Exterior Hearth Extension – The area that extends in front of and to the sides of the firebox opening. The exterior hearth extension should be made from non-combustible materials and should be differentiated from the rest of the room’s flooring.

Ash Dump – Not all masonry systems have an ash dump. This is the area below the firebox where the ashes can be swept down into. A firebox with an ash dump will typically have a metal plate in the firebox’s floor. This metal plate can be opened to brush the ashes below.

Clean-out Door: The clean-out door is located on the outside of the chimney structure near ground level to clean out the ashes from the ash dump.

Unlined Masonry Chimney

Before the early 1900s, masonry systems were not constructed with a flue lining. We refer to those systems as “Unlined Chimneys.” According to the Chimney Safety Institute of America, “Never use a chimney that does not have a liner or has a damaged or improper lining.” [Public Safety Bulletin issued by the Chimney Institute of America: The Importance of Flue Lining in Your Masonry Chimney.] Here in San Diego, however, we have seen unlined chimneys as late as the early 1960s.

When these unlined systems were originally built, the masons used a material called parging (like stucco). They hand-coated over the bricks and mortar joints inside the chimney flue. With time, age and usage, this parging material has worn away, leaving the bricks and mortar joints exposed. In addition, back then the masons used a lot of sand in their mortar. Eventually, these mortar joints disintegrate, leaving gaps and voids. This creates a potentially dangerous situation.

If the unlined chimney is structurally sound and there are no other issues with the system, the system can be “relined.” This is a method where a stainless steel pipe is installed inside the chimney structure. However, if the metal lining is not installed properly or is undersized, the fireplace can be dangerous and/or will not ever draw properly.  Relining a chimney should only be done by a licensed and qualified chimney professional.

Make sure to use a CSIA Certified Chimney Sweep to inspect your system and sweep it if needed. If your masonry chimney is maintained, it will give you warmth and comfort for many years, decades and maybe even centuries to come.

Caveat: Chimneys are built differently in various regions throughout the country. What is common in one region may not be common in another. This information provided here is based on what we see in Southern California.

Rolled up newspaper used in priming the flue

Priming the fireplace flue

Fireplace, , , , , ,

Rolled-up newspaperWhat does a rolled-up newspaper have to do with preventing a smoking problem in a wood-burning, open fireplace?

One of the most common causes for smoking problems in open hearth fireplaces is due to homeowners not priming the fireplace flue before starting the fire, especially during cold weather.  An indication that this is the cause of a smoking problem is if you notice smoke in the room at the beginning of a fire, so it’s a good habit to prime your flue every time you use your fireplace.

Explanation

When it’s cold outside, it’s also cold inside the flue pipe and this cold air is very “heavy air,” especially if it’s cold and/or damp outside. If you light a fire, the smoke rises, but it can’t because the cold air acts like a plug. Instead of the smoke trying to rise up the pipe, the smoke can come into the room where you’re sitting. If you don’t prime the flue, eventually the air inside the pipe will warm up enough on its own but not before filling the room with smoke. Priming the flue is essentially pro-actively starting the draw.  Doing this is especially necessary in chimneys that are on an exterior wall of the house.

Steps to Priming the Flue

1) Open up the damperPriming the flue
2) Place the wood or fire log on the grate3) Tightly roll up a piece of newspaper like a wand or torch and hold it up near the open damper
4) Hold it there for a minute or two until you see the smoke being drawn up the flue
5) Start the wood or fire log on fire

This will heat up the air inside the flue and will get the draw started.

What NOT to do!

It’s potentially unsafe to use the log lighter (the gas pipe under the grate) to prime the flue.  Using the log lighter for this will eventually warm up the air in the flue, but in the meantime, the gases can enter the room where you’re sitting.

In summary….

There is nothing better than a cozy fire on a cold, winter night but that joy can be totally cancelled out by a house full of smoke. Smoking problems can be caused by many reasons but priming the flue is an easy solution for smoking issues. Getting into the habit of priming the flue will go a long way in enjoying that cozy fire in the fireplace.  Bottom line: Don’t throw away those newspapers anymore; they’re good for more than just reading!