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Tankless Water Heater Installation Certificate

A Tankless Water Heater Installation Certificate documents the installation of a gas, propane, or electric tankless (instantaneous) water heater, including gas line sizing, venting category, condensate handling, and required safety devices.

IPC/IFGC (International Fuel Gas Code) venting and gas-piping provisions, NEC (electric units), manufacturer installation instructions, state/local codesValid: One-off (no expiry)

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Sample Tankless WH Cert certificate

Sample Tankless Water Heater Installation Certificate certificate created with CertBox, showing the professional PDF layout with unit fuel type, flow rate, and input rating, gas line sizing and pressure test (gas/propane units), venting category (iii non-condensing / iv condensing) and material

Sample Tankless WH Cert with fictional data. All personal details shown are fake.

What it covers

  • Unit fuel type, flow rate, and input rating
  • Gas line sizing and pressure test (gas/propane units)
  • Venting category (III non-condensing / IV condensing) and material
  • Condensate drain/neutralizer (condensing units)
  • TPR valve, isolation valves, and seismic strapping where required

Who needs a Tankless WH Cert?

Homeowners
Plumbers
Property managers
Building inspectors

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Frequently asked questions about Tankless WH Cert

What is the difference between Category III and Category IV venting?
Non-condensing tankless water heaters vent as Category III (positive vent pressure, flue gas hot enough to avoid excessive condensate) and need a UL 1738-listed special gas vent, typically stainless steel. Condensing units vent as Category IV (positive vent pressure, cooler flue gas that does produce condensate) and need dedicated, sealed Category IV venting — an existing metal B-vent or masonry chimney sized for a non-condensing appliance cannot be reused.
Why does a tankless water heater sometimes need a bigger gas line than the tank heater it replaced?
Tankless units heat water on demand, so their burners fire at a much higher instantaneous BTU input than a storage tank heater delivering the same hot-water output. The gas line has to be sized so the appliance still receives at least its manufacturer's minimum supply pressure at full load, which often requires upsizing from a line that was adequate for a smaller tank heater.

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