Santa's Friend Chimney Service Blog

Why Your Home Could Be Too Airtight

For all their energy efficiency, homes can actually be too airtight. They lack the little leaks and cracks that allow fresh air to enter the house. Without replacement air, exhaust fans are unable to vent stale air. Starved for air, the house can even depressurize, which causes a buildup of carbon monoxide.

It is important, therefore, to learn to recognize signs that your home is not getting enough air. Condensation on windows is a good indicator, as is persistent high humidity. Mold in corners and on pantry shelves is another warning sign, and residual smells from cooking and smoke carry a message to homeowners. Smoke coming into the room from a fireplace should worry you if other possible causes of it have been eliminated, from chimney pots of the wrong size to closed dampers.

Poor ventilation causes serious health problems, including headaches, breathing difficulties, irritated eyes, and dizziness. People who suffer from asthma experience increased and more severe episodes and, as always, the very young and the elderly are at heightened risk. If symptoms appear, open a window on each level of the house about an inch and leave them open for 24 hours. Continue to leave the upper window open, and if symptoms reappear, again open the downstairs window.

You may need to open windows more than an inch. It may even be necessary to have a device installed that will draw in outside air, heat it, and blow it around the house. This will counter the heat loss caused by open windows and will keep heating bills within reason relative to those incurred when the house was suffocating.

Home systems require adequate air to function properly. By way of example, a furnace mixes air with fuel as it combusts. That air comes from somewhere and has to be replaced. If none is available, the furnace will steal it from the flue pipe of the water heater, leaving it with insufficient air. That means the combustible exhaust inside the heater will backdraft into the house, and the by-products will cause a buildup of carbon monoxide. Whether termed too airtight or insufficiently vented, houses need to breathe.

The Different Types of Chimney Liners

A masonry chimney is lined with a ceramic, clay, or metal conduit that contains the products of combustion, directs these outside the home, and protects the walls of the chimney from corrosion and heat. Most fire codes mandate use of a chimney liner due to the safety hazards presented by an unlined chimney. The National Bureau of Standards found that heat moves through an unlined chimney so quickly that adjacent woodwork may catch fire within just 3 ½ hours.

Chimney liners protect homes from heat transferred to combustible materials during fireplace use. Liners also protect chimney masonry from corrosive byproducts of combustion that can reduce chimney life and threaten home occupant safety. The three main types of chimney liners are: metal, clay tiles, and cast-in-place.

Metal liners are made from aluminum or stainless steel and typically used to repair or upgrade an existing chimney. Aluminum is used for a medium efficiency gas system while stainless steel is appropriate for gas, oil, or wood burning systems. High-temperature insulation is installed with this liner to improve performance and safety.

Clay tile is the most common type of chimney liner. It is inexpensive, easy to obtain, and performs well in an open chimney system. However, it does not rapidly absorb or evenly distribute heat during a chimney fire. Unequal expansion may cause flue tiles to crack or split. Clay tiles cannot contain liquid byproducts of combustion from modern gas systems.

A cast-in-place chimney liner is a lightweight, cement-type product. It is castable and installed inside a chimney to provide flue gases with a seamless, insulated passageway. This permanent liner can improve the structural integrity of an aging chimney. Homeowners should have a chimney inspection to determine whether a new metal, clay tile, or cast-in-place liner is required to bring the system into compliance with current fire and safety codes.

Getting Your Chimney Ready for Maintenance

If you have ready any of our posts, you know we recommend that you have your chimney and fireplace professionally cleaned and inspected at least once a year. Doing so ensures that your chimney is safe to operate and that the structure is sound both inside and out. However, before you have a professional chimney sweep come into your home, there are a few things you need to do to make sure your chimney is ready for maintenance.

1. The chimney and fireplace should not be used at least 24 hours prior to any maintenance. This ensures that the fireplace and chimney have properly cooled before the technician performs their tasks.
2. The area around your fireplace may need to be cleaned. By this we mean move your photos and such off the mantle to avoid them getting dirty or broken. While chimney sweeps take the greatest care in protecting all homes they work in, there is no need to invite and accident to happen.
3. Clear out the immediate area around the chimney so the sweep has plenty of space in which to work. If you have chairs or other furniture within about six feet of the fireplace, just move it to the side to allow plenty of space for the technician.
4. Once the chimney sweep arrives in your home, ask them any questions you may have about the process and what they will be doing. You are also encouraged to sit in the background and watch them work. This often serves as an education for the homeowner in that they can learn basic maintenance tasks from the sweep.
5. When the cleaning is done, go over any procedures again with the sweep of which you are unsure. For instance, if you want to know the best way to sweep out the chimney, demonstrate it in front of the sweep to ensure you are following the safest procedures.

What Is a Chimney Damper?

A chimney is actually a complex system comprised of multiple components, one of which is the damper. This metal spring door is located at the top of the chimney or above the fireplace. An attached metal chain runs down the chimney, allowing the user to open and close the chimney from inside the house. When the damper is closed, warm or cool air is kept inside the home, conserving energy use.

Diagram courtesy of the CSIA

If the chimney does not have a damper, at least one-quarter of the energy used in the home is literally going up the chimney. The damper enables the chimney flue to close when the fireplace is not in use. The air generated by a central HVAC system remains inside the home instead of being funneled up the chimney.

A damper also prevents insects, birds, and small animals from entering the chimney. Water and other debris are kept out of the chimney when the damper is closed. If a damper was not included when the fireplace was built, it can be installed later. The best dampers are made from material that will not rust, extending their lifetimes.

Since the damper can only be seen by looking up or down the chimney, many people forget it exists. This causes some to start a fire without first opening the damper. The result is a lot of smoke in the home and no flame in the fireplace. At some point, this is bound to happen but fortunately, opening the damper will remove the smoke.

Spend the money to have a chimney damper installed because it will quickly pay for itself in reduced energy costs. Select a non-rusting damper, not a cheap version made from inferior materials. Have a professional install it and conduct a chimney inspection in the process to verify that the system is not in need of repair.