AirJet FAQs


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AirJet FAQs


General FAQs

Q How are venting systems rated?

A Underwriter’s Laboratories (UL) provides testing of venting systems based on their desired application. This testing includes the continuous operating temperatures as well as momentary higher temperatures that the vent system must handle. B vent systems are listed according to UL 441. L vent systems, including pellet vent systems, must meet the requirements of UL 641. All-Fuel or high temperature systems are tested according to UL 103HT.


Q I’ve seen the term, “negative pressure” applied to these venting systems. What does that mean?

A Venting systems fall into two general classifications: negative pressure systems and positive pressure systems. Negative (often “nonpositive”) pressure systems operate at static pressure that is lower than the room air pressure. Therefore, the joints of negative pressure systems do not need to be gas tight. If a “leak” occurs, it is simply a matter of air being sucked into the system rather than being expelled from the system. Of course, proper design and maintenance of these venting systems will ensure proper operation.

All AirJet venting systems are designed for negative pressure applications.


Q What is “Snap-Lock?”

A This term refers to the groundbreaking pipe connection method developed by AirJet and now being imitated by other manufacturers. For more information, see the AirJet Snap-Lock Training selection under the Solutions menu.


Q I’m confused about installed length. How are AirJet pipe sections measured?

A Pipe sections are specified in overall (end-to-end) lengths. “Effective” or “installed” lengths must accommodate the overlapping snap-lock connection. Subtract 1-3/4 inches (1.75) for each connection when calculating effective or overall installed length. Example: Three (3) individual 1-foot sections joined together would have an overall effective length of 32.5 inches.


Q What is the minimum distance to combustibles?

A It varies by system type; see the other FAQs.


Q Can I cut sections to length?

A No. Doing so would destroy the snap-lock connections, invalidate your warranty, and compromise system performance.



B Vent FAQs

Q What does "B vent" refer to?

A B vent (often “Type B”) refers to venting systems especially designed for Gas-fueled applications, such as the venting of gas appliances like furnaces and water heaters.


Q What sizes of B Vent can I get from AirJet?

A Standard diameters range from 3 inches to 36 inches. Standard lengths for pipe sections are 1, 2, 3, 4, and 5 feet.


Q I’m confused about installed length. How are AirJet pipe sections measured?

A Pipe sections are specified in overall (end-to-end) lengths. “Effective” or “installed” lengths must accommodate the overlapping snap-lock connection. Subtract 1-3/4 inches (1.75) for each connection when calculating effective or overall installed length. Example: Three (3) individual 1-foot sections joined together would have an overall effective length of 32.5 inches.


Q What is the construction of the AirJet B Vent pipe?

A We use a double-wall, air insulated construction. This includes a self-oxidizing aluminum inner liner and a heavy-duty, galvanized steel exterior layer.


Q Is the product UL Listed?

A Yes. Our B vent is UL Listed, complies with UL 441, and tested to 470 degrees F maximum.


Q Is the product fire rated?

A No. B vent systems are not designed to handle combustion and no part of the system is itself flammable.


Q What is the minimum distance to combustibles?

A One (1) inch.


Q Can I put screws in the pipe or connectors?

A ONLY if they are very short screws that do not puncture the inner liner. Puncturing the inner liner invalidates product warranty, negates the UL listing, and can lead to system malfunction.


Q Can I wrap (insulate) pipe sections?

A No.


Q Is B vent appropriate for venting oil furnaces?

A No. L vent is specified for oil-fueled equipment.


Q At what intervals must I support runs of pipe?

A Use wall supports every 4 to 5 feet.


Q Can I common vent a gas fireplace?

A No. Common vent tables are intended for gas furnaces and water heaters only.


Q Can I horizontally terminate?

A Appliances that vent horizontally are not intended for Type B venting.


Q I’m hearing noise in the B vent system. What’s the cause?

A Movement of the vent system relative to the structure is the most likely cause. Movement of pipe relative to supports and roof flashing could also be responsible. If installed according to instructions, the system should accommodate the normal expansion and contraction that occurs during use. Use only recommended supports.


Q Can I attach AirJet B vent to B vent from another manufacturer?

A Yes. We make a universal connector specifically for this purpose.


Q Do I need to make provision for system cleaning such as installing a cleanout tee?

A Unless it is required by your local code, no. Cleaning of B vent systems is unnecessary.


Q Can I install a draft inducer in the system?

A Generally, no, as it would affect the negative pressure of the system. If you must do so, follow the installation instructions provided by the manufacturer AND place the inducer near or at the system outlet so that the entire system remains in negative pressure.


Q Can I paint the vent sections or chimney?

A Yes. Prepare the galvanized surface by washing it with vinegar and water. We then recommend a high temperature paint.


Q Can I attach AirJet pipe to a flexible chimney liner.

A Yes. Use the AirJet FlexJet line or universal connector.


Q What is a Category I appliance?

A As defined by the National Fuel Gas Code it is an appliance that operates with a nonpositive vent static pressure and with a vent gas temperature that avoids excessive condensate production in the vent. Appliances are labeled to indicate which category they are listed as.



FlexJet FAQs

Q What is FlexJet?

A FlexJet is a flexible B vent system intended for two specific applications: flexible chimney liners and flexible gas vent connectors.


Q What is the construction?

A 2-ply aluminum


Q What does the term “drip-free” refer to in FlexJet chimney liners?

A Unlike competitive products, the AirJet FlexJet chimney liner installs INSIDE the bottom connector fitting so that acidic condensate stays inside the liner until it is exhausted up and out of the system.


Q What sizes of FlexJet chimney liners are available?

A Continuous lengths of 25 feet and 35 feet are available as is a 10-foot splicer section and are designed to be cut to size. Diameters include 3, 4, 5, 5.5, 6, 7, 8, and 10 inches.


Q What sizes are available for your flexible gas connectors?

A Lengths of 2, 3, 4 and 5 feet. Diameters of 3, 4 and 5 inches.


Q Can I attach your standard B vent pipe to FlexJet?

A Yes. The integral top connector of our chimney liner provides for fast termination or serves as a positive connection for additional lengths of B vent. The gas vent connectors are designed with our standard Snap-Lock design to connect to the remainder of the B vent system. A universal connector can also ensure a connection to other B vent systems.


Q Is FlexJet UL Listed?

A Yes. These products are listed for B vent use and comply with UL 1777. The chimney liners are listed “for use and may be installed as a liner with gas or propane Category 1 equipment.” FlexJet gas connectors are listed “as a connection between an appliance and Type B gas vent or as a segment of the Type B gas vent.”


Q What is the minimum distance to combustibles?

A For FlexJet liners this question is inappropriate as the product is designed to line the inside of a masonry chimney. FlexJet gas connectors follow the same rule as other B vent systems--1 inch minimum to combustibles.



All Fuel FAQS

Q What are the intended applications of the All Fuel system?

A This system provides the ultimate in safety for burning wood, oil, gas, or pellet fuel. Use this system with wood stoves, free-standing fireplaces, masonry fireplaces, oil and gas-fired appliances, light commercial and industrial appliances, and domestic incinerators.


Q What is the construction of the AirJet All Fuel system?

A It is a triple-wall, air insulated system. It has a stainless steel inner wall, an aluminized steel intermediate wall, and galvanized exterior wall. The “S” series is also available with a heavy gauge, bright, annealed stainless steel, outer jacket.


Q Is it UL Listed?

A Yes. The AirJet 2100° system is listed per UL 103HT. Testing required that the system withstand 2100° temperatures for three (3) 10-minute intervals, 1700° for 10 minutes, 1400° for one hour, and 1000° continuous.


Q What is the minimum clearance to combustibles?

A Two (2) inches.


Q What is that funny looking section with all the holes in it?

A That’s the Starter Section. It is an integral part of the 2100° system. Without it, the system would only be rated to 1700°. Thus, you would not be able to use the system for burning wood. The Starter Section acts as a safety valve at extremely high temperatures. Above these critical flue temperatures, it inhales cool air from outside the system to help maintain a safe, even temperature inside.


Q What connectors are used for adapting to triple wall?

A Use the “SPA” (Stove Pipe Adapter) or the Starter Section.


Q Can I use a 15° elbow and a 30° elbow together to make 45°?

A No. It is a code violation to have a 45° elbow anywhere in the system.


Q Can I vent two appliances through the All Fuel system?

A Each solid fuel appliance should have its own venting system. You can combine the vent systems of oil or gas burning appliances but check to make sure that doing so will conform to all federal and local code requirements.


Q Is the triple-wall design heavy?

A While it is heavier than other AirJet systems, the triple-wall design is engineered for light weight and installation by a single technician. For reference, a 1-foot section of 6 inches in diameter weighs 4.2 pounds.


Q What sizes are available?

A The 2100° triple-wall design is available in 6 and 8-inch diameters. A 10-inch diameter is available for 1700° systems. Pipe sections are available in lengths of 1, 2, 3, and 4 feet.


Q Given the thickness of the triple-wall design, to what does the diameter measurement refer?

A The inside diameter or diameter of the inner wall.


Q What are the outside diameters?

A For 6-inch pipe, the outside diameter is 8.625 inches. For 8-inch pipe, the outside diameter is 12.625 inches. For 10-inch pipe, the outside diameter is 15.25 inches.


Q What is minimum height above the roofline?

A At least 3 feet above the highest point where it passes through the roof and at least 2 feet higher than any portion of the building within an horizontal distance of 10 feet.


Q Is there a maximum height of the chimney?

A Yes. Overall chimney height from the appliance to the outlet should not exceed 50 feet.

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