Utica Boilers MGB Series II/MGC Series 安装指导

6

Provide combustion air and ventilation air in accordance 

with the section “Air for Combustion and Ventilation,” 

of the National Fuel Gas Code, ANSI Z223.1/NFPA 54 or 

applicable provisions of local building codes.
Provide make-up air where exhaust fans, clothes 

dryers, and kitchen ventilation equipment interfere 

with proper operation.
National Fuel Gas Code recognizes several methods 

of obtaining adequate ventilation and combustion air.  

Requirements of the authority having jurisdiction may 

override these methods.

• Engineered Installations.  Must be approved by 

authority having jurisdiction.

• Mechanical Air Supply.  Provide minimum of 

0.35 cfm per Mbh for all appliances located 

within space.  Additional requirements where 

exhaust fans installed.  Interlock each appliance 

to mechanical air supply system to prevent main 

burner operation when mechanical air supply 

system not operating.

• All Indoor Air.  Calculate minimum allowable room 

volume for all appliances in space.  Use a different 

method if minimum volume not available.
A.  Standard Method.  Cannot be used if known 

air infiltration rate is less than 0.40 air 

changes per hour.  See Table 4 for space 

with boiler only.  Use equation for multiple 

appliances.

Volume ≥ 50 ft

3

 x Total Input [Mbh]

B.  Known Air Infiltration Rate.  See Table 4 

for space with boiler only.  Use equation 

for multiple appliances.  Do not use an air 

infiltration rate (ACH) greater than 0.60.

Volume ≥

 

21 ft

3

⁄ACH x Total Input [Mbh]       

C.  Refer to National Fuel Gas Code for opening 

requirements between connected indoor 

spaces.

• All Outdoor Air.  Provide permanent opening(s) 

communicating directly or by ducts with outdoors.
A.  Two Permanent Opening Method.  Provide 

opening commencing within 12 inches of top 

and second opening commencing within 12 

inches of bottom of enclosure.

 

…

Direct communication with outdoors or 

communicating through vertical ducts. 

Provide minimum free area of 1 in² per 4 

Mbh of total input rating of all appliances 

in enclosure.

 

…

Communicating through horizontal ducts.  

Provide minimum free area of 1 in² per 2 

Mbh of total input rating of all appliances 

in enclosure.

B.  One Permanent Opening Method.  Provide 

opening commencing within 12 inches of top 

of enclosure.  Provide minimum clearance of 

1 inch on sides/back and 6 inches on front 

of boiler (does not supersede clearance to 

combustible materials).

•  Refer to National Fuel Gas Code for additional 

requirements for louvers, grilles, screens and air 

ducts.

• Combination Indoor and Outdoor Air. Refer 

to National Fuel Gas Code for application 

information.

0.1

0.2

0.3

0.4

0.5

0.6

262.5

13125

55125

27563

18375

13781

11025

9188

299

14950

62790

31395

20930

15698

12558

10465

* Table values based on boiler only. Add volume for any additional appliances.