TOPIC: Stainless Steel Vs. PVC/CPVC Flue for Condensing Boilers/Water Heaters

B.G. PETERSON COMPANY 2966 HARNEY STREET OMAHA, NE 68131

TOPIC: Stainless Steel vs. PVC/CPVC Flue For Condensing Boilers/Water Heaters

When designing a condensing boiler or water heater system, one important consideration is what material should be used to vent the appliance. For some appliances, the Manufacture will only allow AL29-4C grade of stainless steel. But some Manufactures will also allow CPVC and PVC, under strict guidelines. Let’s look at some questions and answers addressing Stainless Steel vs. PVC/CPVC

1. What are the operating temperatures that each Facts to Know: material can handle? • Did you know that PVC/CPVC is not UL listed FLUE MATERIAL MAXIMUM OPERATING TEMPERATURES to be used as venting material?

Material Flue Maximum Operating Temperatures • PVC/CPVC has no fire Rating. PVC 149°F • PVC/CPVC has no flue warranty. CPVC 194°F • Many cities are adding codes that disallows PPE 230°F PVC to be used for venting appliances. AL-29-4C 550°F • What is the clearance to combustibles for PVC and CPVC?

2. How does Appliance Operating Water Tempera- • Heat Fab AL29-4C stainless steel flue has a tures relate to Flue Temperature Ratings? zero clearance rating for the following:

Appliance operating flue temperatures vary from appliance 6” - 12” to 230F to appliance. An appliance flue gas temperature rise could 14” - 32” to 194F be between 15F and 30F above the entering water temperature. This will determine what flue material is needed. • 1 inch clearance rating is typical to 550F

• See also Heat Fab’s Stainless Steel vs. PVC/ Stainless Steel Boiler Controls: Maximum Operating Water CPVC for a comparison between the two. Temperature = 190°F Maximum High Limit Setting = 200°F

3. How long can CPVC systems 4. What is the thermal expansion be exposed to sunlight? rate for Stainless Steel, CPVC and PVC? If CPVC is used in above-ground, outdoor applications, protection The chart to the right shows the expansion from ultraviolet attack should be rates of each product. Because of the ex- done shortly after the project is pansion rate of CPVC, an Engineer should completed. Typically by shielding provide installation guidelines for the In- or by painting the system with an staller to follow. exterior grade latex paint. Clearance to Combustibles and Framing Requirements Table 1 shows the required MINIMUM AIRSPACE CLEARANCE TO COMBUSTIBLES. “Combustibles” include framing lumber, drywall, plywood, paneling, insulation, wiring and other building materials. This airspace clearance is required for safe operation of the vent. Failure to follow these clearances could overheat the building materials and could cause fire. Max Appliance Minimum Clearance Pipe Size Flue Gas Enclosed Vent Unenclosed Vent Temperature Vertical Horizontal Vertical Horizontal 3" - 5" 230°F* 0" 0" 0" 0" 3" & 4" 480°F 4" 8" 1" 1" 3" & 4" 550°F 4" N/A 1" 1" 400°F 4" N/A 1" 1" 5" 480°F 5" N/A 1" 1" 550°F 6" N/A 1" 1" Table 1. Minimum Clearance to Combustibles * per ULC-S636

Vertical (Floor, Ceiling and Roof) Penetrations Where the vent passes through a floor, ceiling or roof, the hole size or framing dimension must maintain minimum clearances per Table 1. Floor and Ceiling penetrations require a Fire Stop be installed. See Fire Stop section for installation instructions.

Horizontal (Wall) Penetrations PipePipe MinimumMinimum FraminFramingg Dimensions Horizontal systems passing through a combustible wall SizeSize Wall ThimblThimblee require the use of a Wall Thimble, for relative 3" 6.5"6.5" x 66.5".5" temperatures with clearances. See Table 2 for proper 4"4" 6.5"6.5" x 66.5".5" framing dimensions and refer to Wall Thimble section for installation instructions. Non-combustible wall 5" 10"10" x 110"0" penetrations do not require a Wall Thimble. TTableable 2. ((MinimumMinimum FraminFramingg DimensioDimension)n)

TYPICAL INSTALLATIONS

Rain Cap or other Termination See Table 1. (Clearance for Enclosed Horizontal Vent) Flashing & Storm Collar Wall Thimble Horizontal Support See Table 1. (Min. Clearance for Unenclosed Termination Unenclosed Attic Vertical Vent) Firestop & Elbow Support Clamps Support Clamps Firestop

See Table 1. See Table 2. (Min. (Clearance for Framing Dimension for Combustible Unenclosed Wall Thimble) Enclosure Vertical Vent)

See Table 1. See Table 1. (Clearance for (Clearance for Enclosed Vertical Vent) Unenclosed Horizontal Vent)

Firestop

Fig 1. (Vertical Termination) Fig 2. (Horizontal Termination) PI-EZINS 4/17 &OHDUDQFHVWR&RPEXVWLEOHV *DV6SHFLDO*DV9HQW &,3OXV&,DQG,&,3OXV,&, CLEARANCE TO COMBUSTIBLE MAXIMUM FLUE DIAMETER MATERIAL GAS TEMP. (°F) ORIENTATION ENCLOSURE

4” - 12" 0"* 230* Vert & Horiz Fully enclosed 14" - 32" 0"* 194* Vert & Horiz by combustible material on all 4” - 24" 1" 550 Vertical sides 26" - 32" 2" 550 Vertical

Fully enclosed by combustible 4" - 32" Not Allowed 550 Horizontal material on all sides

4" - 8" 1" 9" - 12" 2" Enclosed on a 14" 3" maximum of 2 550 Horizontal 16" - 20" 4" sides (ceiling & sidewall) 22" - 24" 5" 26" - 32" 6"

Noncombustible 4” - 32" 0” 550 Any material *per ULC-S636 4"- 8" 3" 570 Any Enclosed CI Plus/CI 316 4"- 32" CI Plus/CI 316 & 3" 570 Any Un-Enclosed I-CI Plus/CI 316 4"- 24" 3" 570 Any Enclosed 2LO7\SH/9HQW I-CI Plus/CI 316 x The permitted clearances may differ by the appliance manufacturer. The appliance manufacturer’s instructions and applicable local codes take precedence over this document. x 5HIHUWRWKH'H¿QLWLRQVVHFWLRQRIWKLVGRFXPHQWIRULPSRUWDQWGHVFULSWLRQVRIFRPEXVWLEOHDQGQRQFRPEXVWLEOH material. x For venting system that extend through any zone above that on which the connected appliance is located H[FHSWIRURQHDQGWZRIDPLO\GZHOOLQJV WKHYHQWV\VWHPVKDOOEHHQFORVHGZLWKDQHQFORVXUHKDYLQJD¿UH UHVLVWDQFHUDWLQJHTXDOWRRUJUHDWHUWKDQWKDWRIWKHÀRRURUURRIDVVHPEOLHVWKURXJKZKLFKLWSDVVHV x Design any enclosure to permit inspection of the system. x Do not place any type of insulation in any required clearance spaces surrounding the vent system. 5 Stainless Steel VS. PVC/CPVC

Topic UL 1738 Stainless Steel PVC/CPVC Performance and Safety • Large overall Factor of Safety • Minimal overall Factor of Safety • No thermal expansion issues • No provision for thermal expansion • Not susceptible to environmental stress cracking (2-3 times greater expansion rate than stainless steel) • Long history of proven reliable performance • Susceptible to environmental stress cracking (aging and embrittlement process results in leakage potential) • Superior strength, no loss of structural integrity • Cracking and/or failure of solvent welds may cause leakage • Designed for positive pressure • Possible degradation from UV light exposure • Toxic odors if severely overheated

Temperature Limitations • Maximum normal use temperature of 600°F but can • Flue gas temperatures may cause PVC & CPVC to reach their withstand much higher temperatures “Heat Deflection Temperature” (HDT) limits: and Concerns approximately 149°F (PVC) and194°F (CPVC) • Plastics begin to soften/lose strength when HDT is exceeded. Some boilers/water heaters barely qualify to use PVC/CPVC, yet are known to produce higher flue temperatures as they age, resulting in HDT’s being exceeded & possible product failure, including stress cracking.

Available Technical • Extensive technical support available from the manufacturer • Little or no technical support available (for use as a vent system) Support Installation • Fast, safe and easy product installation • Field preparation required (cutting, cleaning, priming, solvent • Complete instructions provided welds and curing) • Laser welded seams and factory installed gaskets • PVC/CPVC manufacturers do not provide installation instructions for flue gas venting applications Codes /Test/Standards • UL 1738 tested, listed and labeled for the application • Not listed to UL 1738 for gas appliance venting • Meets all code requirements (including fire codes) • Performance concerns with through penetrations (firestop locations) • Defined as a combustible and has no flame/smoke rating • Must be fire wrapped within a plenum space (adds material/labor costs)

Application Versatility • Wide range of applications • Limited applications due to temperature limitations • Long term proven performance with Cat II, III, & IV • No double wall option appliances • Not designed or endorsed by PVC/CPVC pipe manufacturers for venting flue gases “Green” Contributions • Recycleable and made from recycled steel • Possibility of chloride leaching and long term leakage • PVC, when utilized in inappropriate applications, can be very damaging to the environment and human health

Warranty • Factory Warranty • No Warranty

SSVSPVCCI-RB-4242-03/12 Rev.2 5030 Corporate Exchange Blvd., Grand Rapids, MI 49512 heatfab® 375 Green Rd. Stoney Creek, ON L8E 4A5 Toll Free: 1.800.433.6341 www.heatfab.com Toll Free: 1.888.SELKIRK (735.5475)