They include old fashioned gravity vent furnaces and the newer fan assisted plus 80 models also known as induced draft furnaces.
Category 1 vertical venting.
80 up to but not including 90 uses metel sectional pipe also known as and sold as double wall b vent amerivent and other names also single wall pipe.
Masonry will use vitreous clay liner.
Ul 641 standard type l vent 3.
0 025 thick type 430 stainless steel all supports and accessories.
Venting guidelines for category i gas appliances single appliance vent tables 1 and 2 continued 10.
1 25 thick cut rigid mineral wool dwkl vt only outer jacket.
Ul 1738 standard special gas vent for category ii iii iv appliances 2.
In some cases transrite has been used which may contain asbestos.
There are only 2 types of vent pipe sold in the hvac market that for 90 plus and that for below 90.
There are many variables dictating how well a vent system will operate.
Category i vent materials are found with older appliances.
Heat loss in the vent 3.
Vent system capacity 5.
Category i central furnaces in canada this type of furnace is a conventionally vented vertical natural draft furnace with or without a drafthood.
All vent installations must be in accordance with the latest edition provisions of the national fuel gas code ansi z223 1 section 7 and or can cga b149 installation codes or the vent tables.
Fan assisted and power vent category 1 furnace.
Type b gas vent models m and mo double wall type b gas vent for approved category i natural gas or propane fired appliances gas furnaces heaters fireplaces and boilers in accordance with nfpa 211 standards for chimneys fireplaces vents and solid fuel burning appliances and nfpa 54 the national fuel gas code.
Flue gas temperature flue gas temperature affects vent operation because the hotter the gases are the lighter they are.
304 stainless steel underwriters laboratories listings united states.
Figure 2 typical fan assist category i furnace category i furnaces are the type most commonly used for residential heating.
Vent connectors shall not be upsized more than two sizes greater than the listed appliance categorized vent diameter flue collar diameter or draft hood outlet diameter.
1 1992 national standard of canada can cga b149 1 and 2 m91 natural gas and propane installation codes with amendment no.
National fuel gas code nfpa 54 ansi z223.
Category i is defined as a gas heating appliance with a flue loss equal or greater than 17 non condensing with a negative vent static pressure.
Restrictions to flow and 6.
