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The CENTROTHERM istp03-4 is a single-wall flue gas test port designed for use with InnoFlue polypropylene venting systems. It provides an integrated analysis port that allows technicians to access flue gas and condensates directly within the vent system for combustion analysis and diagnostics. Rated to UL1738 and ULCS636 by ICC, the istp03-4 is engineered for safe venting performance while maintaining the same tool-free installation characteristics as standard InnoFlue vent lengths. Licensed HVAC technicians performing combustion analysis or commissioning high-efficiency appliances are the primary installers of this component.
The istp03-4 is suited for residential and light commercial high-efficiency condensing appliance installations where direct vent or single-wall polypropylene venting is specified. The test port should be installed as close to the appliance as possible to ensure accurate flue gas readings and reliable diagnostic measurements. It is compatible with 3-inch InnoFlue single-wall vent systems and integrates without disrupting the overall vent assembly.
Designed for use with 3-inch InnoFlue single-wall polypropylene venting systems on high-efficiency condensing appliances.
Installation is performed by licensed HVAC technicians as part of a polypropylene venting assembly. Power down and lock out the appliance before making any vent connections. Position the test port as close to the appliance outlet as the vent layout permits to achieve accurate combustion measurements. No glues, primers, or solvents are required; follow the InnoFlue system assembly instructions and applicable mechanical codes for the jurisdiction.
We pulled together the parts most installs need for this unit, plus a few add-ons worth a look. Check what you need — nothing here blocks checkout.
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