Furnace Ratings and Efficiency Concepts

The video tutorial by Bill Horton at MCC's Applied Technology Center covers gas furnace efficiency and venting systems. It explains how furnace efficiency affects the type of venting system needed to safely expel combustion products. The tutorial details the components of the venting system, the role of the heat exchanger, and how to calculate furnace efficiency using input and output ratings. It also discusses the importance of furnace rating tags for determining efficiency and provides guidance on estimating output when only input ratings are available.

Why is it important to remove combustion products from a structure?

• They improve indoor air quality.

• They help in heating the structure.

• They contain odorless gases that are poisonous.

• They are beneficial for the environment.

What does the venting system begin with in a furnace?

• The burner

• The chimney

• The heat exchanger

• The gas valve

How is furnace efficiency expressed?

• As a ratio of input to output

• As a percentage of fuel burned versus heat used

• As a total BTU rating

• As a measure of gas valve efficiency

What is the furnace burner input rating measured in?

• BTUs per hour

• Cubic feet per hour

• Gallons per minute

• Watts per second

What is the significance of the furnace output rating?

• It determines the size of the venting system.

• It measures the total fuel consumption.

• It indicates the amount of heat extracted by the air being heated.

• It shows the efficiency of the gas valve.

How do you calculate furnace efficiency?

• Subtract the input rating from the output rating.

• Divide the furnace output rating by the input rating.

• Multiply the furnace input rating by the output rating.

• Divide the furnace input rating by the output rating.

What is a therm in terms of natural gas?

• 10,000 cubic feet of natural gas

• 1,000 cubic feet of natural gas

• 100 cubic feet of natural gas

• 10 cubic feet of natural gas

Where can you typically find the furnace rating tag?

• On the gas valve

• Inside or outside the furnace

• On the venting system

• On the thermostat

What should you do if only the furnace input is given on the rating tag?

• Estimate the output by examining the venting system

• Ignore the rating tag

• Use the input rating as the output

• Contact the manufacturer for details

How can you calculate the output rating if you know the furnace efficiency?

• Divide the input rating by the efficiency

• Multiply the input rating by the efficiency

• Subtract the efficiency from the input rating

• Add the efficiency to the input rating