Chimney liners to heating appliances.

Federal government requirements for modern heating equipment to achieve higher efficiencies have been with us since 1992. It has been a challenge to safely vent today's more efficient appliances with their low flue gas temperatures. The damage we see in existing masonry chimneys from these appliances and from hot water heaters venting into the same flue as the heating system has been incrementally getting worse over the past 10 years. Older masonry flues previously venting oil appliances now being used for modern gas equipment and higher efficiency oil appliances seem to be most susceptible to damage. When the existing flue has deficiencies prior to installation of the newer equipment, these conditions can be both costly and potentially hazardous, if they are not addressed when the higher efficiency equipment is installed for the following reasons:

1. Inadequate draft at the appliance resulting in:
A) Poor combustion resulting in reduced efficiency
B) Incomplete combustion resulting in CO production
C) Excessive condensation in appliance resulting in premature failure of equipment.
D) Moisture contamination of vent pipe
E) Moisture problems in brick chimney as excessive condensation "rots" the interior of the flue and leeches through walls causing damage to veneer and plaster
2. Leaking flue gases back into the home:
A) Through failed masonry units in the chimney exposed to the living area
higher in the chimney
B) Due to pressurization issues in the flue flow reversal through draft hood or Barometric damper
3. Flue may not be able to perform as intended due to size
4. Negative draft may not be sustainable due to pressurization issues when multiple appliances are installed
5. If the chimney is unlined, modern gas appliances require by code to be installed into a lined chimney
6. Missing sections of flue tile or gaps between the tile render the flue unsuitable for modern appliances

Chimney liners to heating equipment are not required by code to be insulated and the use of insulation falls onto the manufacturers instructions and the installers wish to provide the best possible performance of the new installation. Many manufacturers and, the National Fuel Gas Code, NFPA 54, recommend insulation but do not require it. However, it has been our experience that many installations still have issues when they are not fully insulated such as sweating behind the liner, which accelerates deterioration and can cause performance issues in chimneys with more than one flue. Premature failure of aluminum liner is accelerated by lack of insulation, which is also true for inferior stainless liners. Excessive condensation still can occur especially when the chimney is on an outside exposed wall of the home affecting efficiency and safe venting.

Written by Kevin Stewart, General Manager
September 1, 2006

Chimney with VENTINOX® System   Chimney w/o VENTINOX® System

Degradation of chimney structure caused by moisture in the flue .
Water damage to interior house walls caused by porous chimneys liners.
Condensation leakage through chimney thimbles and cleanout doors.
Flue condensation caused by cool chimneys.
Staining of chimney masonry due to excessive moisture in the flue.
Insufficient chimney draft caused by improperly sized flues.
Spalling and other masonry damage resulting from freeze-thaw cycles.
Improper clearance to wood framing and other combustible materials.
Cracked flue tiles caused by chimney fire.
Unlined chimney or improperly constructed liner.
Inadequate number of flues within chimney.
Downdrafting or smoking caused by unsteady draft.

The VENTINOX® Chimney Lining System was designed to upgrade substandard chimneys and/or match vent size to the requirements of the heat source as required by the National Fire Protection Association (NFPA 211). It is also ideal for building efficient chimneys in new construction.

Designing a lining system is a difficult task that requires hard choices, which relate directly to product reliability, longevity and ultimately, to the sense of security a good system will provide to the homeowner. We would like you to take a look at our criteria for making these choices.

Mechanical Considerations

Expansion: Since steel expands when exposed to heat, care needs to be taken to give it a shape that does not create stress within the system after it has been installed in a chimney. VENTINOX® absorbs any expansion in its corrugations and does not twist or grow in length. Therefore, Tee sections don't get deformed and VENTINOX® can be mortared solid at the chimney top, which creates a long lasting, watertight seal.

Liner Tightness: This is important for two reasons: First, to keep water vapors and other by-products of combustion within the liner at all times and second, to keep air (oxygen) out during a chimney fire. Using our unique and patented manufacturing process, VENTINOX® liners are continuously welded to form an airtight conduit from the appliance to the chimney top.

Liner Strength: Liners are used in a construction environment. They must be strong enough to take some abuse. Welding the steel and forming it into specially designed corrugations creates great strength and enables VENTINOX® to resist crushing and tearing.

Liner Weight: Heavier is not better. Excess weight is only a nuisance during installations, or when the extra weight could have negative effects on the chimney structure. The lighter weight of VENTINOX® is possible due to our special manufacturing process. The other design criteria can be met without adding extra weight.

Selecting the right steel

Choice of Materials: Is an equally important design consideration. The steel must be corrosion and heat resistant and be suited for specific applications and flue conduit environments. That's why we offer different alloys for different types of heating appliances and applications.

VENTINOX®HiFlex used for fireplaces, wood and pellet burning applications, can withstand severe heating conditions and is warranted even after a chimney fire. Titanium stabilized Type 321 ss resists intergranular corrosion at high temperatures and maintains its strength. This alloy is so heat resistant it is typically used in aircraft afterburners.

VENTINOX®VG for gas burning appliances can withstand the corrosive elements and condensates typical in gas flues. The superferritic Type AL29-4C ss has extreme resistance to chloride pitting, crevice corrosion, stress corrosion and cracking. This steel is typically used in power plant condensers and heat exchangers.

VENTINOX®VFT is made from Type 316Ti ss. It is best suited to withstand the corrosive elements and temperatures typical for oil and gas vent systems. However, 316Ti ss is also strong enough to withstand the high temperatures of wood burning. Typically used in marine chemical environments, pressure vessels and chemical storage tanks.

Fireplace Direct Connect Kits are designed to lead flue gases from a stove or fireplace insert through the damper area and smoke chamber to the bottom of the chimney flue as required by NFPA 211.

FasClamp Components eliminate the need for pre-drilling VENTINOX® liners and the use of pop rivets. This allows for a penetration free connection from the heat source to the outside of the home.

Insulation may be required for certain installations, but insulating VENTINOX® liners always enhances the performance and efficiency of a heating system.

Every VENTINOX® system is backed by our limited lifetime warranty and over 15 years of experience as the leaders in venting technology.

All VENTINOX® Chimney Lining Systems are UL Listed in the United States and Canada.