What Is The Difference Between Type A And Type B Vent Pipe

This piping system incorporates two pipes of different sizes in one unit.

What is the difference between type a and type b vent pipe. Attach a type bw gas vent to a chimney or a type b gas vent to vent through the roof. Install type bw gas vents with a sole header plate to serve as a firestop according to the ul website. B vent systems can only be terminated vertically with several different kinds of caps available depending on your manufacturer s guidelines and requirements. B vent pipe itself is relatively inexpensive and simple to install.

You may be surprised to find two types of copper pipe on the home center shelf type l and type m. The outer pipe draws air for combustion from outside and the smaller pipe occupies the inner position and is used to vent the exhaust fumes. Pex b is not expandable and you should never expand the end of a pex b pipe. The inner pipe of reflecting aluminum heats quickly containing the warm flue gases inside.

The difference is the wall thickness of the copper pipe sizes and therefore the pressure it can handle. The inner pipe is made of reflecting aluminum and heats up quickly. Sometimes referred to as natural vent b vent appliances use pipe b vent that must be installed through the home and terminate above the roof. This type is an ideal alternative to natural vent systems.

Differences can be summarized as follows. It may be difficult to tell the difference between type l and type b vents because they are made from similar components but the vent type should be clearly printed on the vent. B vent must meet the thickness requirements of ul 441 section 6. Type l vents should not be used to vent coal or wood fired appliances.

But for normal in the wall household plumbing type m copper pipe is just fine. For category i appliances nfpa 54 chapter 12 allows for the use of single wall double wall b vent flue pipe or even a chimney. See the chart below for help with measurements. Kink resistance pex a has the greatest resistance pex b the lowest.

As with type b gas vents type bw gas vents may be installed in multiple or single story buildings. Type b systems can involve a multitude of distinct piping components and the termination point is no different. Flexibility pex a is the most flexible allowing for it to be fastened by cold expansion which allows the end to be fluted prior to inserting the fitting. Type b vents come in many different shapes and sizes including oval and round.

The airspace between the inner and the outer pipes provides insulation against heat loss to keep the warmer flue gases on the rise. They also use room air for combustion but the amount of air they use is minimal.