System 636® Flue Gas Venting

The certified system for flue gas venting.

  • 2 system options available in PVC and CPVC
  • Manufactured and supported by PVC & CPVC piping system experts
  • Installer training available

The use of plastic venting systems on gas fired water heaters, furnaces and boilers has undergone a significant change. CSA B149.1 Natural Gas and Propane Installation Code now requires all special venting material to be certified to ULC S636 across Canada. IPEX addressed this market need with System 636, a fully certified flue gas vent system.

Since the inception of System 636, IPEX has made numerous product line additions and extensions to now offer the most complete product offering in the market. Also, System 636 is very professionally represented by IPEX with sales, technical, code issues and training support.

Front and centre to aid installers and inspectors is the System 636 Installation Guide. The contents of this guide are part of the certification process and contain many important aspects of installation to ensure successful, code compliant installations. Issues addressed in the Guide include support spacing, expansion and contraction, solvent cementing procedures and special installation and terminations.

IPEX recommends that installers receive formal training on System 636 every 3 years to ensure proper installation methods are utilized at all times.



We offer System 636 in two distinct materials (PVC & CPVC), each with a unique temperature rating. These venting systems are approved as Type BH vents and are designed for negative or positive pressure venting of gas-fired appliances.

System 636 PVC is classified as Type BH Class IIA vent, suitable for use on appliances with flue gas temperatures up to and including 65ºC (149ºF). Sizes include 1-1/2", 2", 2-1/2", 3", 4" and 6". Coloured white with unique blue certification markings, System 636 PVC pipe is made to sturdy Sch. 40 dimensions to provide a strong, rigid pipe for the application. A full range of System 636 PVC vent fittings and accessories are also offered.

System 636 CPVC is classified as Type BH Class IIB vent, suitable for use on appliances with flue gas temperatures up to and including 90ºC (194ºF). CPVC sizes include 1-1/2", 2", 2- 1/2", 3", 4", 6" and 8". Coloured grey, System 636 CPVC pipe is also made to Sch. 40 dimensions to be tough enough for the application’s demands.


System 636 PVC & CPVC solvent cements are specifically formulated and certified for flue gas venting applications.  

PVC & CPVC Primer is also offered where: 

  • Gas venting system is to be installed in temperatures below 0ºC (32ºF) 
  • Primer is always required on 6” & 8” 
  • Primer is required in some jurisdictions regardless of temperature. Verify with your local Authority Having Jurisdiction 

A certified Transition Cement is available for connections to ABS appliance connectors. 


  • Fully certified as a complete pipe, fittings and cement system
  • 2 system options cover a broad range of operating temperatures
  • No mixing clause of ULC S636 ensures full compatibility of all pipe, fittings and cement
  • Installer training available

IPEX recommends that installers receive formal training on System 636 every 3 years to ensure proper installation methods are utilized at all times.


System 636 PVC carries a ULC S636 Class IIA certification and is certified for use up to and including 65°C (149ºF).
Ensure the proper System 636 PVC Cement and Primer is to be used for installation.

System 636 CPVC carries a ULC S636 Class IIB certification and is certified for use up to and including 90°C (194ºF). Ensure the proper System 636 CPVC Cement and Primer is to be used for installation.

Material type and/or temperature rating is included in the pipe print line as well as on the mandatory orange and black warning label applied to each fitting. All certified IPEX System 636 products carry a Warnock Hersey mark. Warning labels on pipe and fittings are required by ULC S636 and clearly distinguish a certified gas venting system from every day, non-certified plumbing pipe. Look for the orange and black label and the mark of a recognized certification agency as assurance the system being used is certified.

System 636 Pipe, Fittings and Cements are certified as a system and must be installed as such. Different manufacturers have different materials, joining systems and adhesives. Do NOT mix pipe, fittings, solvents, or joining methods from different BH Vent manufacturers, this can result in unsafe conditions. Exchanging components from various manufacturers violates the conditions of certification in the ULC S636 standard and would void the IPEX product warranty. IPEX ABS plumbing pipe and fittings do not meet ULC S636 requirements and must not be installed for flue gas venting. When retrofitting existing water heaters, furnaces or boilers, do not connect System 636 certified vent systems to existing, non-certified appliance vent materials. Replace the entire venting system with listed product to ensure compliance. Before connecting any piping system to an appliance, ensure the manufacturers’ installation instructions are followed, especially with respect to vent material selection.


Combustible Pipes in Non-Combustible Buildings - OBOA (Ontario Building Officials Association) Journal, September 2020

When do the flame spread rating (FSR) of not more than 25 and smoke developed classification (SDC) of not more than 50 come into play?

System 636 Mechanical Business Magazine HVAC Feature

With the cold weather of winter upon us, certainly some of those old midefficiency furnaces that customers have been pleading with you to keep running for “one last season” have decided that this will in fact be their final season, meaning a mid-season replacement project for you.

System 636 Flue Gas Venting Finds Home in HGTV Celebrity Scott McGillivray’s New House

Scott McGillivray approached IPEX to provide piping, conduit and venting for his home because of IPEX’s reputation for providing a broad range of high-quality themoplastic products.

Flue Gas Venting — Innovation and Problem-Solving in Downtown Waterloo

IPEX System 636 PVC pipe is specifically designed to meet the required safety standards for FGV, and normally, it would have been the first choice for this site. However, the building is one metre too tall to permit PVC as per the Ontario Building Code for use of combustible piping in a High Building.