Laars Pennant PNCH, Installation And Operation Instructions Manual

Low Temperature Pennant

Page 7

SECTION 2. 

Venting and Combustion Air

WARNING

For indoor installations, as an additional measure 

of safety, Laars strongly recommends installation of 

suitable Carbon Monoxide detectors in the vicinity of 

this appliance and in any adjacent occupied spaces. 

 AVERTISSEMENT

Pour des installations intérieures, Laars 

recommande fortement, comme mesure de sécurité 

supplémentaire, l’installation de détecteurs de 

monoxyde de carbone adaptés dans le voisinage 

de l’appareil et dans chacune des pièces habitées 

adjacentes.

2.1  Combustion Air

Pennant boilers and water heaters must have 

provisions for combustion and ventilation air in 

accordance with the applicable sections addressing 

requirements for air for combustion and ventilation of 

the National Fuel Gas Code, ANSI Z223.1. In Canada, 

the applicable sections of the Natural Gas and Propane 

Installation Code (CSA B149.1) must be followed. In 

all cases any and all applicable local installation codes 

must also be followed.

A Pennant appliance may receive combustion 

air from the space in which it is installed, or it can be 

ducted directly to the unit from the outside. Proper 

ventilation air must be provided in either case.

2.1.1  Combustion Air From Room

In the United States, the most common 

requirements specify that the space shall communicate 

with the outdoors in accordance with method 1 or 2, 

which follow. Where ducts are used, they shall be of 

the same cross-sectional area as the free area of the 

openings to which they connect.

Method 1

: Two permanent openings, one 

commencing within 12 inches (30 cm) of the top 

and one commencing within 12 inches (30 cm) of 

the bottom, of the enclosure shall be provided. The 

openings shall communicate directly, or by ducts, 

with the outdoors or spaces that freely communicate 

with the outdoors. When directly communicating 

with the outdoors, or when communicating to the 

outdoors through vertical ducts, each opening shall 

have a minimum free area of 1 square inch per 4000 

Btu/hr (5.5 square cm/kW) of total input rating of all 

equipment in the enclosure. When communicating to 

the outdoors through horizontal ducts, each opening 

shall have a minimum free area of not less than 

1 square inch per 2000 Btu/hr (11 square cm/kW) of 

total input rating of all equipment in the enclosure. 

Table 3

 shows data for this sizing method, for each 

Pennant model.

Method 2

: One permanent opening, commencing 

within 12 inches (30 cm) of the top of the enclosure, 

shall be permitted. The opening shall directly 

communicate with the outdoors or shall communicate 

through a vertical or horizontal duct to the outdoors 

or spaces that directly communicate with the outdoors 

and shall have a minimum free area of 1 square inch 

per 3000 Btu/hr (7 square cm/kW) of the total input 

rating of all equipment located in the enclosure. This 

opening must not be less than the sum of the areas of 

all vent connectors in the confined space.

Other methods of introducing combustion and 

ventilation air are acceptable, providing they conform 

to the requirements in the applicable codes listed 

above.

In Canada, consult local building and safety 

codes or, in absence of such requirements, follow 

CSA B149.1, the Natural Gas and Propane Installation 

Code.

2.1.2  Intake Combustion Air

The combustion air can be taken through the 

wall, or through the roof. When taken from the wall, it 

must be taken from out-of-doors by means of the Laars 

horizontal wall terminal (see 

Table 2

). When taken 

from the roof, a field-supplied rain cap or an elbow 

arrangement must be used to prevent entry of rain 

water (see 

Figure 2

).

  Use single-wall galvanized pipe, per 

Table 

4,

 for the combustion air intake (see

 Table 2

 for 

appropriate size). Route the intake to the heater as 

directly as possible. Seal all joints with tape. Provide 

adequate hangers. The unit must not support the 

weight of the combustion air intake pipe. Maximum 

linear pipe length allowed is 50 feet (15.2m). Three 

elbows have been calculated into the 50-foot (15.2m) 

Size

Each Opening*

Square inches

Square cm

500

125

807

750

188

1213

1000

250

1613

1250

313

2020

1500

375

2420

1750

438

2826

2000

500

3226

*Net Free Area in Square Inches / 

Square cm

Area indicated is for one of two openings; one at floor level 

and one at the ceiling, so the total net free area could be 

double the figures indicated.
This chart is for use when communicating directly with the 

outdoors. For special conditions and alternate methods, refer 

to the latest edition of ANSI Z223.1.

Note:

  Check with louver manufacturers for net free area of 

louvers. Correct for screen resistance to the net free area 

if a screen is installed. Check all local codes applicable to 

combustion air.

Table 3. Combustion Air Openings.