Gas Fitter Practice Test

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Study for the Gas Fitter Test. Enhance your knowledge with flashcards and multiple-choice questions, each accompanied by hints and explanations. Ace your exam!

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What is the correct vent size and maximum input for a water heater rated at 50,000 Btuh located 3 feet from a chimney in a 25-year-old house?

4 inch diameter, 73 cfh
4 inch diameter, 67 cfh
4 inch diameter, 68 cfh
4 inch diameter, 81 cfh

The correct answer is: 4 inch diameter, 67 cfh

For a water heater rated at 50,000 Btuh, it's important to ensure that the venting system is appropriately sized to facilitate efficient operation and proper venting of combustion byproducts. The 4-inch diameter vent is standard for such applications. The maximum input for the venting system should correspond to the manufacturer's specifications and the specific vent sizing tables used in the field, which often consider factors like the type of fuel used and the installation environment. In general, a venting system is sized based on the input rating in Btuh and the distance to the termination point, as well as the specific venting method used. In this context, selecting a maximum input of 67 cfh aligns with acceptable safety standards for a system near a chimney, ensuring that the water heater can operate effectively without causing backdrafts or other issues related to improper venting. Therefore, the choice that reflects a correct vent size and maximum input, considering these factors and standard guidelines for water heater installations in existing residential structures, is indeed correct.