Weil-McLain PFG-7 User Manual

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Combustion air and ventilation openings

Combustion air and ventilation openings must comply with Sec-

tion 5.3, Air for Combustion and Ventilation, of National Fuel 

Gas Code ANSI Z3.1-latest edition, or applicable local build-

ing codes. Canadian installations must comply with CAN/CSA 

B149.1 or . Installation Codes.

  Provide adequate combustion and ventilation air to: 

•  Ensure proper combustion
•  Reduce risk or severe personal injury or   

death from flue gas spillage and carbon   

monoxide emissions.

  Do not install an exhaust fan in the boiler room.

Boiler installation must ensure sufficient openings in building 

and boiler room to provide adequate combustion air and ventila-

tion. Consider construction tightness of building when deciding 

whether additional outside openings may be needed.
Older  buildings  with  single-pane  windows,  minimal  weather-

stripping  and  no  vapor  barrier  often  provide  enough  natural 

infiltration and ventilation without dedicated openings.
New construction or remodeled buildings are most often built 

tighter. Windows and doors are weather stripped, vapor barriers 

are used and openings in walls are caulked. As a result, such tight 

construction is unlikely to allow proper natural air infiltration 

and ventilation.

Select the boiler location

• 

Consider all connections to boiler before selecting a location.

• 

Boiler must be installed so gas control system components are pro-
tected from dripping or spraying water or rain during operation or 
service.

• 

Non-combustible floor ONLY. See “Boiler foundation”, Page 5.

  To avoid personal injury, death or property damage, 

keep boiler area clear and free from combustible 

materials,  gasoline  and  other  flammable  vapors 

and liquids.

Installation clearances

Suggested minimum clearances for servicing

• 

4 inches for cleaning and servicing, left side.

• 

18 inches for access to controls and components, front.

• 

48 inches from top for cleaning flueways.

• 

6 inches on remaining sides.

PFG-5 through PFG-7:  Required minimum clearances 

to combustible surface in alcove installations (see 

below)
PFG 5 thru 7:  Top 4” 

R. Side 5” 

Front: Alcove 18”

 

Rear 5” 

L. Side  5”

PFG-8:  Required minimum clearances to combustible 

surfacel in alcove installations
PFG  8:    Provide  minimum  4”  between  jacket  and  any  com-

bustible wall(s). Provide minimum 48” between jacket top and 

combustible ceiling or surface above the boiler.
Install in a space large in comparison to size of boiler.

Clearances from piping materials to combustible sur-

faces

• 

Single wall vent pipe must be at least 6 inches from combustible 
surface.

• 

Type “B” double wall metal vent pipe - refer to vent manufacturer’s 
recommendation for clearances to combustible surface.

• 

Hot water pipes must be at least ½” from combustible surface.

Section I:  Installation

Air from inside building (boiler in interior room):

• 

Tightly constructed buildings must be provided with openings to 
outside for combustion and ventilation air. These openings must be 
sized to handle all fuel burning appliances, exhaust and ventilation 
fans and fireplaces.

• 

When openings to boiler room are taken to interior spaces, provide 
two permanent openings: a combustion air opening within 1 inches 
of floor and a ventilation opening within 1 inches of ceiling. Each 
opening must provide a minimum free area of one square inch per 
1,000 Btuh input of all appliances in room plus requirements for 
any exhaust fans in room. The interior space supplying combustion 
and ventilation air must have adequate infiltration from outside.

Air directly from outside to boiler room:

• 

Tightly constructed buildings must be provided with combustion 
air and ventilation openings to boiler room which are adequate to 
handle the boiler needs plus the needs of all other fuel-burning ap-
pliances, fireplaces and exhaust or ventilation fans.

• 

Combustion  and  ventilation  openings  connecting  directly  or  by 
ducting to outside, or to attic or crawl spaces that freely connect 
with outside, must be sized as follows:
1.  Outside  wall  or  vertical  ducting  -  one  square  inch  per  4,000 

Btuh input of all appliances in room plus requirements for any 
exhaust fans or other appliances in room.

.  Horizontal ducting - one square inch per ,000 Btuh of all appli-

ances in room plus requirements for any exhaust fans or other 
appliances in room.

3.  All ducting must be same size as permanent openings. Minimum 

size of ducting must be no less than 9 square inches.

4.  Other size ducting must comply with local codes.