What is a Flue Liner and Why do You Need One?

Flue liners are an important part of any furnace, water heater, boiler, or fireplace system. Liners have been required by code since 1927, but have been in use since the 1870’s. In a nutshell, the purpose of a flue liner is to keep toxic flue gasses such as Carbon Monoxide, other aldehydes, and tar vapors inside the flue and allow them to exit the house. It was found early on that with masonry chimneys, the mortar joints tend to deteriorate over time and develop cracks and gaps that allow gasses to leak through them. So, liners were invented. Vitreous clay tile flue liners were created to line the interior chimney so that flue gasses could not escape the flue. This is extremely important for the health and safety of the occupants of a home.

However, over time, rainwater, moisture, and acidic flue gasses eat away at mortar joints between the liner sections. Clay tile flue liners are made in two-foot sections and installed ahead of the exterior masonry chase. They have a bed of mortar between each section. When these mortar joints erode, they create gaps between the liner sections – and we are back to square one with toxic gasses leaking into the house. 

A liner has been removed and one remains

When rehabbing a house, a contractor may find that there is no liner installed in a masonry chimney. This is more common in older homes with utility flues serving heating appliances and water heaters, but occasionally is found with fireplaces as well. It is extremely common, however, to find a flue liner with missing mortar joints. This can be remedied in most cases with a method using a ceramic joint filler, which is applied using a heavy-duty vibrating bell sponge while pouring the mix from above the flue liner. It involves special equipment and trained professionals to do the job. In cases with large gaps between liners this method cannot be used, and relining is necessary.

A second common issue with flue liners is incorrect sizing. If a liner is not correctly sized to the appliance, smoking or backup of toxic gasses can result. This often occurs when a high efficiency furnace is installed, leaving a water heater to vent on its own, which it cannot do in an oversized flue. A liner for the water heater will be necessary unless a replacement water heater that vents out the side is used instead. An incorrectly sized flue liner serving a fireplace will cause backup of smoke and toxic gasses into the home.

Stainless steel liner with a single flue tile on top

The third common issue with clay tile flue liners is damage from a chimney fire. As fireplace inspectors we see this on a daily basis, and in most instances, the homeowner had no idea that they had a chimney fire unless they caught it at the time, or a neighbor knocked on their door after they saw flames shooting out of the chimney. Most chimney fires are of short duration because as flammable creosote burns it expands to ten times its size and snuffs out the fire. But even a short duration chimney fire can cause a lot of damage to flue liners, usually leaving vertical and sometimes horizontal breaks behind. These breaks open to as much as ¾” when the appliance is used, once again allowing gasses to escape. The only solution is to reline the flue. Fortunately, homeowner’s insurance covers chimney fire damage since it is considered a “hostile” fire. If a home was purchased within 12 months prior to finding the damage the new owner may have recourse with the seller, who can file a claim on their insurance. Chimney repair can be expensive, and the last thing a new homeowner wants is a huge un-budgeted-for expense after a home is purchased. This is why an inspection of all flues in a home is so important prior to purchase. 99% of Home inspectors do not inspect chimneys, only a chimney sweep with the proper equipment can, and should, do a chimney inspection using a chimney camera system. If timing does not allow for an inspection, figure in extra cost in your rehab estimate based on the size of the chimney.

Clay tile flue liners being installed as masonry is built up

Relining involves removal of the cement cap and extraction of the clay tile flue liner, installation of a replacement stainless steel liner with insulation, and rebuilding the cement cap. Other demolition such as removal of a damper casing, firebrick, or a wall may be necessary. Smoke chambers are often in poor condition and need to be parge coated with insulating mortar.  It is important to use a liner with the same I.D. dimensions as the previous liner, or in some cases, larger, and the only way to do that is to take the old liner out first. In rare cases, the flue is oversized so installation of a new liner may be possible without extracting the old liner.

Codes must be followed with flue liners – Chapters 10 and 18 in the International Residential Code cover most of this information, and the National Fire Protection 211 Standard for Chimneys, Fireplaces, Vents, and Solid Fuel Appliances also applies since it is the industry standard. We also follow the NFPA 54 National Fuel Gas Code.

A stainless steel flue liner being prepped

 

 

 

A professional chimney contractor should do this type of work since they are familiar with the codes and standards and have the equipment and expertise to do the job. In the greater Kansas City area and other jurisdictions across the U.S., a Class DM Master Mechanical (HVAC) Contractor License is needed in order to reline flues, and a permit is required for the work, with an inspection by the building codes inspector.

 

The cost to reline a flue can very greatly and is determined by the type, size, and length of liner needed and difficulty level of the job.

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Marge Padgitt is a 35-year chimney industry veteran. She trains professional chimney technicians across the U.S. and is the author of The Chimney and Hearth Pro’s Resource Book, and Wood-Fired Heating and Cooking, along with many training DVDS and presentations. Contact her at hearthmastersboss@gmail.com, 816-461-3665, or www.chimkc.com.

Masonry Chimneys v Earthquake

By Marge Padgitt

Just after 7:00 a.m. on September 3, 2016 parts of Missouri, Kansas, Oklahoma, Texas, Iowa, Nebraska, and Arkansas experienced a 5.7 magnitude earthquake which originated in northwest Oklahoma. The cause may be due to the practice of disposing oil and gas field wastewater deep underground. The temblor was similar to one experienced in the same location in November of 2011, although this recent earthquake lasted longer.

In Pawnee County, Oklahoma, the epicenter of the quake, reports damaged masonry structures, and one man was injured when part of a fireplace fell on him as he protected his child. In Kansas City, several reports have already been made by homeowners who noted that their brick chimney is cracked severely.

Masonry chimneys are particularly susceptible to damage by earthquake. Due to the nature of their rigid structure, chimneys are likely to crack while being shaken by a tremblor. Parts that can be damaged are mortar joints inside and out, bricks, stones, blockwork, flue liners, fireplaces, smoke chambers, and interior facial walls.

Photo by Brian Sherrod, United States Geological Survey - United States Geological Survey Multimedia Gallery, Public Domain, https://commons.wikimedia.org/w/index.php?curid=39847217

As a matter of precaution, we suggest that homeowners inspect their chimney immediately after an earthquake, both inside and out, then call a professional chimney sweep to do a more thorough inspection with a chimney camera system and a keen eye trained to find things homeowners may miss.

Tips:

• Look for obvious fresh clean breaks in the mortar, bricks or stone on the exterior chimney and foundation
• See if there are any pieces of masonry lying on the ground or on the roof.
• Check the facial wall inside the house above and around the fireplace opening and note any fresh breaks
• Examine the brick firebox (fireplace) and look for fresh cracks
• Take photos of your findings and note the date and time
• Have a professional chimney sweep examine the interior smoke chamber and flue liner for any fireplaces or the flue liner for the utility flue, and the entire exterior chimney after an earthquake

While the most severe damage will occur near the epicenter of an earthquake, chimneys in any location that experience shaking should be inspected, even if there is no visible exterior damage. The interior flue liner may be damaged with no indication of this on the exterior chimney chase.

Chimneys on commercial buildings, churches, and schools should be examined thoroughly by a professional immediately after an earthquake.

A damaged chimney can be a danger to occupants or passersby. If damaged badly enough a facial wall or chimney may partially or completely fall down. Cracks in the flue or smoke chamber can allow deadly Carbon Monoxide to enter the interior of the house or building. CO is odorless, tasteless, and silent.  CO alarms do not alert occupants if the air being checked is less than 9 ppm (parts per million), and it is known that low levels of Carbon Monoxide can cause long term irreversible brain damage. Visit www.coheadquarters.com for more information on Carbon Monoxide.

To find a CSIA Certified Chimney Sweep in your area visit www.csia.org or www.mcsc-net.org. In Kansas City visit www.chimkc.com.

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Marge Padgitt is a CSIA Certified Chimney Sweep, NFI Certified Woodburning Specialist, and is a 30-year industry veteran. She is an author and speaker, and CEO of HearthMasters, Inc. in Kansas City. Contact her at margepadgitt@comcast.net or 816-461-3665. 

Home Buyer Beware!

Buyer beware: always have chimneys inspected by a professional chimney sweep

The Midwest Chimney Safety Council recommends an inspection of all chimneys and flues at the time of purchase of a home by a professional chimney sweep.  Home buyers may be in for a big surprise and major expense if they don’t have an inspection completed prior to closing of the sale.

Home inspectors do not inspect the interior or exterior chimney as a normal part of a home inspection. Most home inspectors do not have the necessary equipment or training to do chimney inspections, therefore, it is wise to have a professional do the job.

Unfortunately, many home buyers have found out after the sale that their chimney or fireplace is unusable. A typical inspection of a masonry chimney will reveal that the interior flue has missing mortar joints due to exposure to rain, moisture and acidic flue gasses. The older the home, the more likely there are problems.

In many cases, the seller has had a chimney fire without knowing it, and the interior clay tile flue liner is cracked and broken. Other typical findings are damaged smoke chambers, rusted dampers, missing chimney covers, poor flashing, and damaged cement crowns. Issues at the top of the chimney can’t be viewed without using a ladder, or in some cases, scaffold. Home inspectors don’t normally climb ladders or own scaffold.

The average chimney repair job runs into thousands of dollars. In the greater Kansas City area, the average relining job which involves removal of the damaged liner, scaffolding, and installation of a new flue liner costs between $8,000 to $18,000.  In a recent case, an inspection of five chimneys and eight fireplaces in one home revealed $50,000 in damages.

In a 2012 transaction in Kansas City Missouri, the seller had a chimney flue relined with a new flue liner but the installer put a liner in that was too small. Months later, when the new owner started a fire in the fireplace it smoked badly and caused smoke damage to the entire home. An inspection by a professional chimney sweep revealed that the liner installed was too small for the chimney to draft properly. Because the contract was with the previous owner, the new owner had no recourse and had to pay $14,000 to have the steel liner extracted, then the old tile liner extracted, and a new properly sized flue liner installed. Flue sizing is extremely important to the operation of the appliance and if not done correctly can cause major problems such as smoking, odors, and Carbon Monoxide back up.

If damages are found prior to closing the buyer will know exactly what condition the chimney and fireplaces are in and how to proceed with the negotiation. If damages are due to a chimney fire the seller’s insurance will cover the damages, however, it is wise for the buyer to choose the company who will do the work because sellers usually want to go the least expensive route and often hire unqualified chimney companies to do the work.

A typical Level II inspection with an internal chimney camera involves running the camera through the damper and into the smoke chamber, then the flue. This type of inspection can reveal damages to masonry, mortar joints and flue tiles that can’t be seen using the naked eye and a mirror. A professional chimney sweep who has been trained in this type of inspection will be able to identify potential hazards, fire risks, and Carbon Monoxide risks.

The MCSC recommends that all flues be inspected including fireplace flues, furnace and boiler flues, and chimneys serving wood and gas stoves and inserts. If a chimney flue has an accumulation of creosote, the creosote must be removed so that the inspector can see the flue liner. Creosote is very flammable and should be removed by a qualified chimney sweep.

Visit www.mcsc-net.org or www.csia.org for more information or to find a CSIA Certified Chimney Sweep.  

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Marge Padgitt is the editor of Wood-Fired Magazine, and CEO of a chimney contracting company in Kansas City, MO. Visit www.chimkc.com for more information. 

Spring preparation tips for wood burners

As difficult as it is to think about cold weather during the nice spring and summer months when the trees are green and the flowers are in full bloom, wood burners need to start prepping for fall now.

Since wood needs to be cut, split and stacked months in advance so that it dries out properly, now is the time to get that project completed, and get some exercise to boot. There are several types of log-splitters available that can make the job much easier. Prices range from $150 for a hand-operated splitter, to $3,000 for a professional gas splitter.

Fotolia.com 

Wood should be stacked off the ground, away from the house, with a covering over the top but not on the sides-- so wind can blow through and dry the wood out. For the serious wood-burner, a wood shed with a permanent roof will offer years of protection from the elements. Wood should be kept away from the house because creepy crawlies like brown recluses like to hide in between the logs. Check wood with an inexpensive moisture meter to be sure it contains less than 20% moisture content before burning.

Any dry wood will do- but hardwood will burn for a longer time since it is denser than softwood. By using hardwood less time is involved in loading up the wood stove or fireplace insert, but softwoods will burn nicely. Stay away from dry pine and hedge, however, because they burn so hot and fast there is a greater risk of a chimney fire or damaging a wood stove or fireplace.

Another maintenance task that should be completed in the spring is chimney sweeping. The Midwest Chimney Safety Council suggests that a professional CSIA Certified chimney sweep do the job. Professional sweeps are trained to check things that the layperson may not be aware of such as proper chimney and connecting pipe installation, clearances to combustibles, wall and floor protection. If used for primary heating purposes, wood-burning stoves and insert flues or chimneys should be swept at least twice during the wood-burning season and once after to be sure that flammable creosote is removed.

Chimney sweep at work. HearthMasters, Inc. 

All wood creates creosote- even dry hardwood, and removal is critical to avoid chimney fires. Chimney fires can not only damage chimneys and connecting pipes, but may escape into the home and cause a house fire.

Check exterior masonry chimneys in the spring for damaged, missing, or spalling bricks (brick faces popping off due to moisture penetration), missing or deteriorated mortar joints, bad flashing or gaps in the flashing, cracked or deteriorated cement crown, and missing or improper chimney covers. Apply masonry water repellant sealer on a dry, calm day to help slow down the deterioration process.

For a prefabricated chimney check the wood chase for wood rot, holes from woodpeckers or squirrels, rusted metal chase tops, and damaged chimney covers.

All of these chimney maintenance items are best addressed in the spring and summer before cold weather sets in and makes work more difficult and expensive.

Is your chimney tall enough to work right?

By Marge Padgitt

Fireplaces and wood-burning stoves only work right when everything is built or installed correctly, and that includes the height of the chimney. There are several factors to take into consideration when planning for the termination height of a masonry or factory built chimney system. 

When building, or rebuilding, a chimney the builder should check the height to be sure that it not only conforms to National Fire Protection 211 Standards, which is the standard used in the industry for chimney construction, but also conforms to International Residential Code requirements. Both the standard and the code require that a chimney be three feet taller than the high side of the roof where it exits, and two feet taller than anything (roof, trees, dormers, etc.) within ten feet.  This is the first step in determining what the finished height of the chimney should be. If a fireplace smokes, the height of the chimney could be a factor.

Short flues: Additionally, keep in mind that a short flue (under 12’) may not draft correctly, so the chimney height may need to be extended if a fireplace is on an upper level of the home. It is generally accepted in the industry, although not a code requirement that flues under 12 or

15 feet in height may not draft well.  This may mean that the chimney height needs to be taller than code requires so it will function properly. 

Stack effect: The second factor to consider is the construction of the home. If a chimney is located on a room addition or end of a house, and the main section of the house is taller than the chimney, the house will act like a chimney and pull air upwards. This can cause what is known as “Stack Effect,” and pull smoke back in to the house from the fireplace while it is in operation, and smells when it is not in use.  For this reason, always plan the location of a chimney carefully. 

Trees: If trees or branches are within ten feet of the chimney they can affect draft and cause downdrafts.  If necessary, have trees and limbs cut back further than ten feet away.  

What not to do: Don’t ever add a section of tile flue liner to the chimney to make it taller without extending the exterior brick chase at the same time. Flue liner joints must be below the exterior in order to prevent them from falling over, and if installed incorrectly can be a hazard. 

Homeowners may want to consult with their professional chimney sweep before adding a room addition or constructing a new home to determine the best location for the chimney and fireplace. In some cases, the chimney simply cannot draft correctly due to the location and house construction, and it may need to be built higher, or removed altogether. An alternative fireplace, such as a direct vent gas insert, may be a good alternative to an open wood-burning fireplace in

some cases. Direct vent fireplaces are closed sealed systems that use outside air for combustion and are not as affected by the house construction as open fireplaces. 

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Marge Padgitt is a CSIA Certified Chimney Sweep and NFI Certified Woodburning Specialist. She is a 30-year industry veteran and has written over 200 articles. Marge is the author of The Chimney and Hearth Pro's Resource Book and The Homeowner's Chimney and Fireplace Manual. See more info at www.hearthmasters.net.