The Stack Effect

 When Buildings Act Like Chimneys

As heat escapes a roof, cold air is sucked in through the basement and first floor windows, In summer, the opposite happens. [Click image for slideshow.]

Hot air rises, and cold air sinks, but stack effect ventilation reverses in summer

Like wind, the stack effect can move large volumes of air through a building envelope. In the winter, the warm air in a heated building is lighter (less dense) than the cold air outside the building; that warm bubble of air wants to rise up and out. The flow of air leaving the top of the building draws cold air into cracks at the bottom.

The reverse happens in summer when hot air outside of an air-conditioned house can push cooler indoor air down from the ceiling and out of cracks in the basement (see drawing). At least in theory, this can lead to moisture problems on the top floor.

But the differences in temperature and pressure aren’t as great during the summer as they are during the winter. When it’s cold outside, the pressure created by the stack effect is 4 pascals per story of height; when it’s hot, about 1.5 pascals per story of height.

Unlike most other pressures, the stack effect acts every hour of every cold day, and the pressures generated by the stack effect are significant.

Leaky buildings consume tremendous amounts of energy. Air leaks can contribute to condensation, compromising the quality of the indoor air. For high-rise residential buildings in cold weather, that isn’t the worst-case scenario — it’s the normal scenario (see "Why revolving doors were invented," below).

WHY REVOLVING DOORS WERE INVENTED

If the stack effect is a big deal in two-story houses, imagine what kind of pressure it causes in high-rise buildings. This pressure is so significant in fact that "when skyscrapers were first developed at the turn of the century, people also had to invent revolving doors because you couldn’t open the front door due to the stack effect pressure," says Straube. "The cold air was rushing in with so much pressure that it was difficult to push the exit doors open."

Stack effect feeds on itself

"Air entering the building make the downstairs people cold, so they turn up the thermostat. When the people upstairs get all that heated air, they open the windows to cool off. This increases the flow of air leaving the building, which increases the flow of air coming up from the bottom floors — so the people downstairs plug in space heaters.

“You wind up with this merry-go-round — sucking air up the bottom, heating it up, and blowing it out the top,” says Straube. “There’s so much airflow in the elevator shafts that you can float! You can just put out your arms and you’ll float in the middle of winter in many of these buildings.”

What is that Smell Coming from My Fireplace

It’s common to find remedy from the odor by cleaning the creosote and soot out of the chimney. Hot, humid summer days and rainy days adding moisture will produce undesirable odors from a dirty chimney. A chimney cleaning will also find any decomposing material problems and will also clean the creosote out of the chimney. The creosote soaks into the chimney walls so even after a chimney cleaning is complete this may continue to contribute to the smell. Although, as long as the draft is working correctly and there is no negative air flow in the home, the smell should not enter your home.

If the chimney inspection and cleaning does not rid the home of the odor, next it is best to seal the chimney from water sitting in the chamber and causing a musty smell. This can be done by installing a top mounted damper or chimney rain cap to keep the rain water and moisture out. The top mounted damper is your best bet for sealing the chimney off from rain and humidity and it prevents animals and leaves from getting into the chimney shaft as well.

Dirty chimneys are often the smelly culprit!

After the water issues are taken care of, the next concern is the air pressure in the home. Most chimneys will have some type of smell to them, but this is typically not a problem because the chimney draft drives this smell out of the flue and away from the inside room. But when there is negative air pressure in the home, air has to come from somewhere to fill this vacancy. Because the chimney has a low point of resistance, this additional air typically comes through here, bringing the chimney odors along with it. Often found in newer tight homes, this negative air pressure can reverse the flow of draft from the chimney back into the home.  This problem also often shows up during the warmer months after weatherizing has been done to the home or venting changes and improvements have been made. Other causes of the negative air pressure include exhaust fans, HVAC systems, additional chimneys, combustion appliance flues, range hood, and the installation of many more household appliances.

Here is the Proof - Babies Do Not Like Smelly Chimneys!

A quick solution to the negative air pressure is to crack a window at all times to let the pressure change through this outlet rather than the chimney. But for a more permanent approach to the negative air pressure, follow these steps till the smell no longer enters the home.

1. Close the fire damper when the fireplace is not in use. While this will sometimes solve the problem, most dampers are not perfectly sealed, so they problem may still occur.
2. Have a glass fire screen installed to keep the warm air from escaping when there is a fire in the fireplace.
3. Have a professional install a top sealing damper onto the top of the chimney that is controlled by a metal chain and hangs down the chimney to the hearth. These can be a huge help in monitoring the airflow.
4. Provide outside combustion air to other combustion appliances that started the air pressure problem in the home.

The smell could be a result of a number of problems, here is a quick guide to discovering  the source of the odor.

If your chimney smells like ——– Then it most likely is from…

Bad Barbeque/Asphalt ————- Creosote build up
Musty Odor ————————– Water sitting in your smoke chamber
Rot and Decomposition ———— Fallen leaves combining with damp soot and rotting in the chimney
Animal Scat or Dead Critters —— Animals leaving behind thoughtful “gifts” in your chimney or not being able to escape and passing away

It is never a bad time to get a chimney inspection. Even in the middle of the summer, with months till you even start to think about cold weather activities, chimney professions are available to inspect and clean your chimney. Don’t let an intrusive smell draw all of the attention, take care of the odor as soon as it is noticed and enjoy your fireplace all year long. Call me with questions, Chris Brown (704)526-6348

he Most Notable Chimneys in the World

The Chimney’s Claim to Fame – The Most Famous Chimneys in the World!

It may be hard to imagine a world renowned chimney, but these chimney examples will have even those who are somewhat less enthused by chimneys, very impressed. While for the most part chimneys are built for functional purposes, there are a few cases where the design of the structure goes far beyond that of simple functionality and instead develops into ostentatious displays of wealth or unusually emphasized structural components.

Most Creative Chimney
A one-of-a-kind chimney was designed by Rudolf Steiner and finished in 1914. The chimney dominated the building that housed the boiler room for the 15 building complex. The unique structure called Das Heizhaus is part of The Goetheanum complex that is the center of the School of Spiritual Science and the Anthroposophical Society in Donarch, Switzerland. Rudolf Steiner, a spiritual leader and founder of the Waldorf Education system among many other accomplishments, used his work to reflect his belief in a form follows function style of building with the boiler building’s dominant feature of a prominent chimney. He also believed in integrating his architecture with nature in every one of his designs, which is again exemplified in the supposed leaves growing out from the sides of the chimney structure.

Artists are often known to pay attention to things others may ignore and Antoni Gaudi is no exception. Known for his unique designs that are considered to fall somewhere in between Modernism and Art Nouveou, he is often referred to as “God’s Architect”. Throughout his life as an architect, he was in constant demand and created designs considered to be way ahead of his time. Each project Gaudi took on became elaborately decorated. Every last inch of each of his structures right up to the chimneys on the roof of the homes were carefully and intentionally designed. For this reason, three of the most notable chimneys in the world were designed by the Spanish architect Antoni Gaudi, all of which are today UNESCO World Heritage Sites.

Casa Mila was built as an apartment building for a wealth couple in Barcelona, Spain.

Casa Mila
One of the most popular architects in history, Gaudi receives recognition for his fantastic tile work and creative art deco designs. One of the unique sets of chimneys he created is at Casa Mila, an apartment building originally built for Roser Segimon and Pere Mila. Don’t bother looking it up, although his work appears “gaudy” to many it is not the source of the word! The set of ventilation towers on top of the roof of the building look like guards keeping a lookout from the top of the complex. The distinct chimneys are known as espanta bruixes, which means “witch scarers” in Italian. The whole structure has the peculiar look to it that only Guadi’s buildings have and at the time it was built, it was considered a controversial design, but now the building is highly regarded and revered and visited regularly by awed tourists.

Casa Batllo
Along these same lines of Casa Mila, on a building restored by Antoni Gaudi, the artist and legend created a colorful variety of chimneys for Casa Batllo. Locally known as the “House of Bones”, Casa Batllo was just like every other Gaudi creation where every part of the building looks distinctly like only his designs do. This includes the lack of straight lines and use of colorful ceramic tiles incorporated into every area of the home. Even the decorative curvy chimneys that cheerfully lined the rooftop are completely covered in colorful tiles.

Palau Guell
The most distinct feature of this building, besides the chimneys of course, is the fact that the entire home is based around the living room. This home was ordered by one of Gaudi’s close friends and is one of his largest projects. The decorative chimneys look almost as if they are delicious candies with their bright colors and fun designs. The home was completed in 1888 and after a recent renovation is now once again open to the public.

Most Chimneys in One Place
The Chateau of Chambord, which Francis I started in 1519, has 365 chimneys, each different, each decked out with sculpted shields, wreaths, columns, animals or nymphs. The building, which was never completed, was constructed by King François I in part to be near to his mistress the Comtesse de Thoury. The Chambord is the largest château in the Loire Valley; it was built to serve as a hunting lodge for François I. The château also features 440 rooms and 84 staircases.

The Oldest Chimneys
One of the most famous older chimneys Thornbury castle is a Tudor structure that was built in 1511 for the 3rd Duke of Buckingham, but the fancy chimneys were added on 3 years later. This castle was later confiscated by King Henry VIII and this notorious king occupied the castle for a short time with Anne Boleyn. The intricate designs on this castle’s majestic chimneys are made from molded and carved bricks. It is one of England’s oldest and most historic homes.

We see evidence of earlier chimneys, but perhaps the oldest chimneys still standing are in the massive kitchen building of the 12th-century abbey of Fontevrault, where Henry II of England, his wife, Eleanor of Aquitame, and their son Richard the Lion Heart are buried. The abbey’s five huge wood-burning fireplaces, used for cooking and smoking meat and fish for a monastic community of several hundred persons, are ingeniously connected to 20 pencil-shaped stone chimneys that blend harmoniously with the structure’s Romanesque architecture.

The Tallest Chimney
Currently the record goes to the Ekibastuz GRES-2 Power Station with a 1337 ft tall coal-fueled power generating station that was built in 1987 in Ekibastuz, Kazakhstan. The US currently has a 1217 ft. chimney at another coal burning power station in Homer City, Pennsylvania which falls short of the tallest in the world but the US will be taking back that distinction soon in Arizona with a unique Solar Chimney.

Future Tallest (& Greenest) Chimney
In the coming years, the tallest chimney in the world will also be the second tallest structure in the entire world. Set to soar to 2625 ft the tower will be only about 100 feet less than the Burj Khalifa (the world’s tallest structure) recently completed in Dubai. This “chimney” will be over a half mile high will take solar heated air and draft it up the chimney which will in turn generate power by use of wind turbines inside the structure! This will be the cleanest chimney in the world as well since there is nothing burning, but since it is used to draft air up and into the atmosphere we do consider it a chimney stack none-the-less. Not your average chimney for sure, and no there is no fireplace attached. The huge chimney is to be located in the middle of Arizona and this solar energy generating structure will cost about $750 million to build. It will then create enough energy to run 200,000 homes in the area. This new chimney is planned to be built by 2015 and will be twice the size of the Empire State Building in New York City. This enormous solar powered energy plant will be built by an Australian company called EnviroMission. Besides a small test project in Spain, nothing quite like it has ever been built. This is sure to be one famous chimney!

Don’t let your notions of how a chimney should look become limited by the types of chimneys you grew up with. The spectrum goes far beyond the classic red brick and the designs can be as wild as you can imagine!

The Chimney Cap Question

Do I really need a chimney cap?

Even though a chimney cap is a minor and relatively inexpensive installation many homeowners question whether it is necessary or not. The truth is that this small amount of metal protecting your chimney can prevent numerous mishaps from taking place and save a homeowner thousands of dollars in unnecessary chimney repair or damage expenses. So ultimately you may not need a chimney cap in place for functional purposes, but unless you want headaches down the road (and little critters running through your home), a properly installed chimney cap is a must. A chimney cap will prevent animals from entering your home, keep the moisture out, and protect the roof from burning embers starting a house fire.

Keep the animals away.

During the cooler months, animals walking along your roof will feel the warmth around the chimney from the fire below. For this reason they will make their nests close to or inside of the small and comforting space of the chimney flue. It doesn’t take long for an unwelcomed family of critters to move into your chimney. Squirrels can create a 4 foot deep nest in less than 24 hours! Installing a simple chimney cap with mesh siding will prevent these animals from homesteading within your residence.

Bird and squirrel nests built in the enclosed space of a chimney also creates the problem of blocking the path for what usually goes out of the top of the chimney. Typically smoke and gases from the fire below will exit the home through the chimney. With large squirrel or bird nests in the way though, these harmful gases will end up backed up into the rooms of your home. This backup can cause smoke and soot damage and even carbon monoxide poisoning.

Unwanted animals nesting, sparks and embers escaping and moisture getting in and damaging your chimney are the main reasons to have an adequate chimney cap.

What’s so bad about moisture?

Rain, snow, and ice all create problems for your chimney if they are allowed in the chimney flue. Moisture causes deterioration problems within the structure and when mixed with certain types of soot it can become even more harmful to the inside structure of your chimney. The freezing and melting of ice and snow is especially hard on the masonry chimney walls, chimney crown and chimney liner. This freeze and thaw damage can cause severe problems such as cracks in the structure during the winter months which often leads to costly repairs. Therefore, it is best to not allow the excess moisture into the chimney in the first place by diverting the elements away from the chimney with a chimney cap that is right for your chimney.

Protect against unruly embers.

Burning embers from the fire below get sent up and out of the chimney along with the burning gases. These pieces of the fire that are still lit escape out of the top of the chimney and can cause chimney fires and damage to your roof. These problems are entirely avoidable with the addition of a chimney cap and spark guard to prevent the burning particles from escaping.

Will adding a chimney cap create draft problems?

A common misconception that comes along with the topic is the worry that caps will cause problems with the chimney draft. At times adding a chimney cap incorrectly can create draft problems. But if you hire a professional chimney sweep to do the job, a chimney cap can often fix a draft problem. There are specially designed chimney caps that reduce draft problems or correct existing ones. It is important to call a professional chimney sweep rather than to attempt the job on your own because incorrect installation can lead to creating more problems rather than fixing the existing one. Also, the quality and manufacturing processes of a chimney cap that professionals install are held to a much higher standard than standard retail caps available at the big box hardware stores. These caps will also typically come with better manufacturer and installation warranties as well. A properly installed cap will not only help solve existing problems but also prevent new ones from taking place.

So how do I get one?

Now that you realize the importance of having a chimney cap in place, it is important to choose the right type. Lowes and Home Depot may have bargain deals that look appealing for chimney caps, but these caps are typically made of aluminum and do not provide adequate coverage to keep your home safe and your chimney clean. For these reason, it is best to pick either the brand that installed your metal chimney liner, or to go with a chimney cap installed by your local chimney sweep. Call your chimney sweep and get a recommendation for the best type of chimney cap for your specific chimney. Chimney caps come in a variety of shapes and sizes that are useful in different cases, but the most important element is what it is made from. Copper and stainless steel are the most commonly used metals by chimney sweeps as they are also the most durable and best for the job. Also, if you have a multi-flue chimney, one large cap can be put in place rather than installing multiple individual ones. This provides a sleeker rooftop look.

With a professionally installed chimney cap in place you can sleep soundly and rest assured that the only outside creature climbing around in your chimney will be the jolly old Santa Claus.

Fireplace Can Raise Heating Bill

Fireplaces Are Great To Look At!

A fire in the fireplace is relaxing, but they don't heat your home as thoroughly as you may think. Fireplaces deliver 10 percent or less of the fire's heat to the room and will increase your heating bill in two ways.

First, firewood costs more than the value of the delivered heat. Seasoned oak firewood must cost less than $20 per cord (a cord is a stack 4 feet wide by 4 feet high by 8 feet long) to provide heat from a fireplace at a cost comparable to a heat pump, according to the University of Tennessee Agricultural Extension Service.

Fireplaces also require a large volume of air from the chimney. The incoming air cools the rest of the house, causing the primary heater to operate more than if you had no fire.

Here are some tips to care for your fireplace efficiently:

• If you never use your fireplace, plug and seal the chimney flue.

• Check the seal on the flue damper and make it as snug as possible. Add caulking around the fireplace hearth.

• Keep your fireplace damper closed unless a fire is going. Keeping the damper open is like keeping a 48-inch window wide open during the winter; it allows warm air to go right up the chimney.

• When you use the fireplace, reduce heat loss by opening dampers in the bottom of the firebox (if provided) or open the nearest window slightly -- approximately 1 inch -- and close doors leading into the room. Lower the thermostat setting to between 50 and 55 degrees Fahrenheit.

• Install tempered glass or metal doors or heat sheilds. Placed in front of the fireplace, these sorts of devices will limit the amount of warm room air that escapes the house when the fireplace is not is use. Doors work particularly well when a fire is burning down for the night, but the damper has to remain open to allow the smoke to vent. While the fireplace is in operation, glass doors should remain open, since most of the warmth produced by a fireplace is in the form of radiant heat. If closed, the glass will deflect radiant heat back into the fireplace and reduce the heat output to the room.

• Use grates made of C-shaped metal tubes to draw cool room air into the fireplace and circulate warm air back into the room.

• Look at new fireplace designs. Circulating fireplaces have heat circulation ducts built into the masonry fireplace. These pull air from the room, circulate it around a metal firebox and send it back, warmed, into the room. Some of these units have built-in fans to increase the flow of air and heat. Made of metal, circulating fireplaces warm quickly and cool rapidly once the fire is extinguished.

• Consider fireplace inserts. An insert is basically a metal wood stove that slides neatly into the fireplace cavity. They are relatively easy to install, and can improve a fireplace's efficiency. Before adding one, however, make sure to have your fireplace and chimney inspected and cleaned by Affordable Chimney Service (704)526-6348

Chimney Swift

A "flying cigar," 

the Chimney Swift is rarely seen perched. Its high-pitched twittering is a familiar sound during summertime in the city as it flies high above, catching small flying insects.

Cool Facts

• Before European settlement of North America, the Chimney Swift probably nested in caves and hollow trees. The swift benefited greatly by the construction of chimneys and the increased availability of new nest sites. Recent changes in chimney design, with covered, narrow flues, have decreased the available nest sites and may be a factor in declining population numbers. For information about a Chimney Swift tower made specifically for nesting swifts, go to the North American Chimney Swift Nest Site Research Project.
• Chimney Swifts do not sit on perches like most birds, but instead use their long claws to cling to the walls of chimneys and other vertical surfaces.
• Swifts are among the most aerial of birds, flying almost constantly except when at the nest or roosting at night. The Chimney Swift bathes in flight, gliding down to water, smacking the surface with its breast, then bouncing up and shaking the water from its plumage as it flies away.
• The Chimney Swift is gregarious, with large numbers of swifts roosting together in a single chimney or air shaft during the nonbreeding season. Nonbreeding swifts will roost together in the summer too, and this behavior has fooled people into thinking that the Chimney Swift nests in colonies. In fact, only one pair nests in a single chimney. The pair may tolerate other swifts roosting in their chimney, though, further confusing people watching the swifts from the ground.
• The fast, erratic flight of the Chimney Swift is characteristic of small swifts. It gives the very distinct impression that the swift is beating only one wing at a time, alternating wings. Careful investigation has shown, though, that a swift beats both its wings at the same time just like all other birds. The illusion comes at least in part from the frequent banking and turning.

Call Affordable Chimney Service For Chimney Service Needs (704)526-6348

German Chimney Sweeps Face Loss of Monopoly

For 70 years, German chimney sweeps have held monopolies in assigned districts, with customers required by law to pay for their services. The sweeps are about to learn if the German government will challenge an EU ruling that the arrangement blocks free trade.

To Germany now, where one of the most secured jobs in the country is about to become a little less so. The German government requires that all households use the services of a chimneysweep. And that's given the sweeps a monopoly on much more than shoveling ashes.

But that's now about to change as NPR's Emily Harris reports from Berlin.

Tom Drust is a third generation chimneysweep, and he's a traditionalist. He really does wear a black top hat to work. Today, he's dropping a metal brush on a rope weighted with a heavy ball down a 200-year-old chimney. And hand over hand, hauling it back up again.

Mr. TOM DRUST (Chimneysweeper, Germany): (Speaking foreign language)

HARRIS: Once is enough for this chimney he says.

Mr. DRUTH: (Through translator) It's not that cold. The woodstoves haven't been burning for very long, and we come regularly.

HARRIS: Regularity is what chimney sweeping is all about in Germany. The government mandates how often chimneys must be cleaned and how often modern heating and ventilating systems must be checked, those jobs are also assigned by law to chimneysweeps. A master sweep is in charge of a district of some 2,000 or more households. Customers may not shop around. This makes safety regulations a lot easier to enforce, says the head of Germany's sweep association, Frank Saber(ph).

Mr. FRANK SABER: In this case, the government has to control about 8,000 companies in Germany. And otherwise, you have to control 80 million people and the heater.

HARRIS: But European Union competition officials call the set-up illegal. Under threat of a lawsuit from Brussels, Berlin is proposing a compromise; keep the districts' monopoly for jobs involving public safety and environmental protection. For other services, homeowners would be allowed to hire any qualified sweeper. That's not enough for homeowner Paul Abahart(ph).

Mr. PAUL ABAHART: (Through translator) Every two years my heating technician checks the system, so all the checking and cleaning that he does has already been done. It's a double service that makes no sense at all.

HARRIS: Chimneysweeps are traditionally seen as bringers of good luck. But a minority of Germans really hates the sweep system. And often hate their assigned chimneysweep.

At a small demonstration on the outskirts of Berlin, they play a song that essentially accuses chimneysweeps of being spies. They say that was the point of Hitler era laws that required sweeps be German and lead an exemplary life.

Those rules were chucked in a 1969 revision, and now sweeps are generally forbidden from sharing personal information about customers. But the obligation to let sweeps in and pay for them riles some people to the extreme. Manfred Rickmirer(ph) has been fighting chimneysweeps for five years.

Mr. MANFRED RICKMIRER: (Through translator) They can check whether people who have a TV actually pay the fees for that, whether people with a dog pay the tax for the dogs, or if a person has an expensive lifestyle that the tax authorities might like to know about. Of course, we can't prove these, but it's possible. It happened in the Third Reich, and the DDR, so why not now?

Mr. DRUST: (Speaking foreign language)

HARRIS: We have nothing to do with spying says sweep Tom Drust. He laughs, ask the elderly owner of a 19th century restaurant, whose chimney Drust has just cleaned, how he feels about sweeps. And he pauses then tells how the original 15th century building here burned down because of a chimney fire.