LAARS Mighty-Stack TL00-199 - Installation, Operation and Maintenance Instructions - Manual (Page 6)

LAARS HEATING SYSTEMS Page 6
1I. Combustion Air Supply
The water heater location must provide enough
air for proper combustion and ventilation of the
surrounding area. See the latest edition of ANSI
standard Z233.1 or in Canada, CAN/CGA-B149.1 or
.2, and any local codes that may be applicable.
In general, these requirements specify that if the
unit is installed in a confined space, there must be at
least two permanent air supply openings. One opening
should be within 12 inches (305mm) of the ceiling,
and the other should be within 12 inches (305mm) of
the floor.
For installation in U.S.A.:
Water Heater Outside Air Inside Air
Size Area † Area ††
199 50 sq in 199 sq in
323 sq cm 1284 sq cm
The area indicated is for one of two openings; one at floor
level and one at ceiling, so the total net free area would be
double the figures indicated. For special conditions, refer
to NFPA54 ANSI Z223.1.
† Outside air supply – Combustion air is supplied directly
through an outside wall.
†† Inside air supply – Combustion air is supplied from inside
the building.
NOTE: Check with louver manufacturers for Net Free Area
of Louvers. Correct for screen resistance to the New Free
Area if a screen is used.
Table 5. Minimum Recommended Air Supply
to Water Heater Room.
Outside Air Supply: When combustion air is
supplied directly through an outside wall, each
opening should have a minimum free area of one
square inch per 4,000 BTUH input of the total input
rating of all appliances in the enclosed area.
Inside Air Supply: When combustion air is
supplied from inside the building, each opening
should have a minimum free area of one square inch
(6.5 sq cm) per 1,000 BTUH input of the total input
rating of all appliances in the enclosed area. These
openings should never be less than 100 square inches
(645 sq cm).
For installation in Canada:
NOTE: In Canada, follow Canadian Standard
CAN/CGA-B149 or local codes.
Exhaust Fans or Vents: Any equipment which
exhausts air from the room around the unit can deplete
the combustion air supply. Such equipment can also
reverse the action of the venting system. This could
cause flue products to accumulate in the space where
the water heater is installed. Additional air must be
supplied to compensate for any exhaust effect.
5. Turn off the water heater before you do any
pressure testing on the gas lines.
If you will be testing at a pressure greater than
1/2" psig (3.5 kPa) –
Disconnect the gas line before the water heater
and before the shutoff valve for the water heater.
If you will be testing at a pressure equal to or
less than 1/2" psig (3.5 kPa) –
Turn off the manual shut off valve ahead of the
water heater gas controls.
6. Provide gas to the water heater at the pressure
shown in Table 4. The regulator is preset at the
factory, and normally requires no further
adjustment.
Distance from Gas Meter Pipe Size
0' – 200' 0 – 60 m 1¼"
NOTE: These figures are for Natural Gas (.65 Sp. Gr.), and are
based on 1/2" water column pressure drop. Check supply
pressure with a manometer, and local code require-
ments for variations. For LPG, reduce pipe diameter one size,
but maintain a 1/2" minimum diameter. A “normal” number of
Tees and elbows have been taken into allowance.
Table 3. Gas Piping Size.
Water Column
Natural Gas Propane (LP)
i.w.c. kPa i.w.c. kPa
Minimum Supply
Pressure*
6 1.5 11 2.7
Maximum Supply
Pressure**
10 2.5 14 3.4
Manifold Gas
Pressure
4 1.0 9 2.2
* Listed for purposes of inlet adjustment.
** The gas supply should not exceed this pressure.
Table 4. Gas Pressure Measurement.
Note: When measuring the inlet supply pressure, the
water heater and all other gas appliances sharing the
water heater gas supply line must be firing at
maximum capacity. Low gas pressure could be
caused by an undersized gas meter or an obstructed
gas supply line.
7. Before operating the water heater, the complete
gas supply system and all connections must be
tested for leaks using a soap solution.
Caution
Some solutions used for leak testing may cause
corrosion or stress cracking. (These include soap
and water.) To prevent this, rinse the piping with
water after testing.