LAARS HEATING SYSTEMS
Page 6
Boiler Size
Outside Air
Area in Sq. In.*
Inside Air
Area in Sq. In.* (sq cm)
50
15
97
100
645
75
20
129
100
645
100
25
161
100
645
125
32
206
125
807
160
40
258
160
1032
225
60
387
225
1452
*Area indicated is for one of two openings; one at floor level and
one at the ceiling, so the total net free area would be double the
figures indicated. For special conditions, refer to NFPA54 ANSI
Z223.1. In Canada refer to the National Standard CAN1-
B149.1 or .2 which differs from this table.
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.
In general, these requirements specify that boiler
rooms which represent confined spaces should be
provided with two permanent air supply openings; one
within 12 inches (305mm) of the ceiling, the other
within 12 inches (305mm) of the floor.
4.
Disconnect the boiler from the gas supply pipe
before pressure testing the pipe for gas leaks.
Provide gas supply pressure to the boiler as
follows:
Inches Water Column
Natural Gas
Propane (LP)
Minimum
5.5
10
Maximum
9
14
NOTE: The boiler and all other gas appliances
sharing the boiler gas supply line must be firing at
maximum capacity to properly measure the inlet
supply pressure. Low gas pressure could be an
indication of an undersize gas meter and/or obstructed
gas supply line.
5.
The correct burner manifold gas pressure is
stamped on the rating plate. The regulator is pre-
set at the factory, and normally requires no
further adjustment.
6.
Before operating the boiler, the complete gas
supply system and all connections must be tested
for leaks using a soap solution.
1G. Combustion Air Supply
The boiler location must provide sufficient
air supply for proper combustion, and ventilation
of the surrounding area as outlined in the latest
edition of ANSI standard Z223.1 or in Canada,
CAN/CGA-B149.1 or .2, and any local codes that
may be applicable.
Important
See gas line selection chart, Table 4 previous page,
for gas line sizing. In all cases, pipe size is larger
than inlet connection on heater. Run pipe size
shown in chart and reduce at heater inlet.
Table 5. Minimum Recommended
Air Supply to Boiler Room.
Figure 4. Dimensional Information.
Dimensions in inches (mm)
Outside Air Area*
Sq. In.
sq cm
Inside Air Area*
Sq. In.
sq cm
Dimensions
Water
Gas
inches (
mm)
Conn.
Conn.
Size
A
B
C
D
E
V
in.
in.
50
13-3/8
340
27-3/4
705
23-5/8
600
21-3/4
552
26-1/2
673
4
102
1-1/4
1/2
75
13-3/8
340
27-
3/4 705
24-1/8
613
21-3/4
552
27-1/2
699
5
127
1-1/4
1/2
100
16-7/8
429
28-3/4
730
24-1/8
613
22-3/4
578
27-1/2
699
5
127
1-1/4
1/2
125
16-7/8
429
28-3/4
730
23-5/8
600
22-3/4
578
27-1/2
699
6
152
1-1/4
1/2
160
20-3/8
518
28-3/4
730
23-5/8
600
22-3/4
578
27-1/2
699
6
152
1-1/4
1/2
225
25-5/8
651
31-1/2
800
23-1/4
591
23-3/4
629
27-1/2
699
7
178
1-1/4
*
3/4*
*1/2 for propane
