Exhaust Vent Piping Materials
• Use only 2” or 3” solid PVC/CPVC schedule 40 PVC/CPVC or ULC S636 pipe and fittings.
• Venting requirements in USA and Canada are different. Please consult with the most recent edition of the
National Fuel Gas Code (ANSI Z223.1 / NFPA 54) or CAN/CSA B-149.1 as well as local codes for
applicable venting regulations and restrictions.
• For installation in Canada, field supplied plastic vent piping must comply with CAN/CSA B-149.1 (latest
edition) and be certified to the standard for type BH Gas Venting Systems, ULC S636 components of this
listed system shall not be interchanged with other vent systems or unlisted pipe/fittings. All plastic
components and specified primers and glues of the certified vent system must be from a single
manufacturer and not intermixed with other system manufacturer’s vent system parts. The supplied vent
adaptors are certified as part of the combination water heater.
• For all units installed with vertical exhaust, must have an additional approved condensate drain installed on
the Horizontal section of the exhaust vent. Fittings must be ULC S636 approved.
• PVC/CPVC pipe/fittings have been approved for use on this appliance with zero clearance to combustibles.
Intake Vent Pipe Materials
• Solid PVC schedule 40 PVC or ULC S636 pipe and fittings and ABS pipe and fittings can be used for
combustion air intake on FLOWMAX products.
• Transition cement must be used for the ABS pipe connected to the PVC appliance adaptors.
• All plastic components and specified primers and glues of the certified vent system must be from a single
manufacturer and not intermixed with other system manufacturers vent system parts.
Allowable Vent Lengths
Equivalent Lengths
• Reduce the maximum vent length accordingly for each elbow used.
• Each 2”/3” 45⁰ elbow equates to 2.5 linear feet of vent pipe.
• Each 2”/3” 90⁰ short radius elbow equates to 7.5 linear feet of vent pipe.
• Each 2”/3” 90⁰ long radius elbow equates to 5 linear feet of vent pipe.
• The maximum length listed is for exhaust vent only. The intake length should be equal length.
• The total maximum equivalent vent pipe distance cannot exceed 100ft for horizontal and vertical venting
distance.
• The maximum lengths are not including elbows.
• Exceeding the maximum venting distances will cause the appliance to malfunction or cause an unsafe
condition.
Minimum Vent Lengths
• 3" Diameter - 6" pipe (Iength) plus one elbow.
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