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HVAC - Combustion air requirements


Opinion

Inquiry:

00-03

Subject:

Combustion Air Requirements

Code:

UMC Sec. 104 (a) and (b): Additions, Alterations or Repairs to Existing  Mechanical Systems
UMC Sec. 601(a) and (b): Combustion Air Requirements for Existing Buildings

Submitted by:

MN B.O. Uniformity Committee

Approved by:

Thomas R. Joachim, State Building Official

Issue Date:

January 12, 2000

Question:

Is combustion air required to be added into an existing home when the water heater is replaced, if not already provided?

Answer:

Yes. "Additions, alterations or repairs to existing systems must be made without requiring the existing mechanical system to comply with all the requirements of the code, provided that the addition, alteration or repair conforms to that of a new mechanical system.

Comments:

In existing buildings of 'ordinary tightness,' the UMC allows all, or a portion of, the combustion air for fuel-burning appliances to be obtained from infiltration. This, in most cases, will have to be a judgment call on behalf of the Building Official. Keep in mind the tightening of existing homes by means of replacement siding, windows and doors, insulation, etc.

Approved by Building Codes and Standards Access Committee September 26, 1996.

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