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Combustion Safety - Problem Set 3.2

Source(s) or Contributor(s)
Pacific Northwest National Laboratory
Question

  1. For a residence with three natural draft Category I vented appliances with natural drafts of 120,000 Btu/hr, 150,000 Btu/hr, and 100,000 Btu/hr, all sharing an indoor airspace with an ACH of 0.5 with a ceiling height of 8 feet, how much indoor surface area is required for these appliances to be considered combustion safe?

  2. A residence has three natural draft Category I vented appliances sharing an airspace with an ACH of 0.25.  Two of the appliances are not fan-assisted with natural drafts of 80,000 Btu/hr, 120,000 Btu/hr, and the third appliance is fan-assisted and has a natural draft of 100,000 Btu/hr.  If the total surface area of the indoor space is 2000 square feet, how high do the ceilings need to be to ensure safe combustion operation of all three appliances?

  3. A residence has two natural draft Category II vented appliances and one natural draft Category III vented appliance, all of which are fan-assisted, sharing an airspace with an ACH of 0.5.  What would be the required air volume for safe combustion operation?

    1. 50 cubic feet per 1000 Btu/hr of each appliance.

    2. 21 cubic feet per ACH per 1000 Btu/hr of each appliance.

    3. 15 cubic feet per ACH per 1000 Btu/hr of each appliance.

    4. The required air volume for each of the appliances will be provided to the residence owner by their individual manufacturers.