LAARS Mighty Therm HH-PH (Sizes 175-400) - Installation, Operation and Maintenance Instructions - Manual (Page 16)

LAARS HEATING SYSTEMS Page 16
with CAN1-B149.1 or .2 and all local codes
that apply.
2. Check the rating plate to make sure the boiler is
fitted for the type of gas being used. Laars
boilers are normally equipped to operate below a
2000 foot (610 m) altitude. Boilers equipped to
operate at higher altitudes have appropriate
stickers or tags attached.
3. If a gas pressure regulator is required, the
installation must be in accordance with the latest
edition of ANSI Z223. In Canada, the installation
must be in accordance with CAN1-B149.1 or .2
and all local codes that apply.
4. The figures in Table 4 should be used to size the
gas piping from the gas meter to the boiler.
5. Install a sediment trap (drip leg) ahead of the gas
controls (see Figure 27). Fit the trap with a
threaded cap which can be removed for cleaning.
6. Install a manual gas shut-off valve for service
and safety. Check the local codes.
7. Disconnect the boiler and its individual shut-off
valve from the gas supply system during pressure
test of the system at pressures higher than ½ psi
(3.4 kPa).
8. Gas supply pressures to the boiler are listed in
Table 5.
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.
9.
Do not exceed the maximum inlet gas pressures
specified. Excessive pressure will result in
damage to the heater's gas controls. The
minimum pressures specified is for gas input
adjustment.
10. The correct burner manifold gas pressure is
stamped on the rating plate. The regulator on the
gas valve is preset at the factory, and does not
normally need adjustment.
11. Before operating the boiler, test the complete gas
supply system and all connections for leaks using
a soap solution.
Caution
Since some leak test solutions (including soap and
water) may cause corrosion or stress cracking,
rinse the piping with water after testing.
2G-2. Special Precautions for Propane Gas
Propane gas is heavier than air. Therefore, do not
install boilers using propane gas in a pit or locations
where gas might collect. Locate boilers a safe distance
from propane gas storage and filling equipment.
Supply Pressure Natural Gas Propane Gas
Water Column in. kPa in. kPa
Minimum 6.5 1.6 11 2.7
See Rating Plate
Maximum 10 2.5 14 3.4
Table 5. Gas Supply Pressure Requirements.
Figure 27. T-Fitting and Sediment Trap.
MANUAL SHUT-OFF
VALVE
GAS
SUPPLY
INLET
T-FITTING
3" (76 mm)
MIN.
UNION
NIPPLE
CAP
TO
BOILER
INLET
Distance from Gas Meter or Last Stage Regulator
0-100 feet 100-200 feet 200-300 feet
0-30 m 30-60 m 60-90 m
Boiler Nat. Nat. Nat.
Size in. mm in. mm in. mm
175 1 25 1¼ 32 1¼ 32
250 1¼ 32 1¼ 32 1½ 38
325 1¼ 32 1½ 38 1½ 38
400 1¼ 32 1½ 38 2 51
Notes:
1. These numbers are for natural gas (0.65 Sp. Gr.) and
are based on ½ inch (13mm) water column pressure
drop. Check supply pressure with a manometer, and
local code requirements for variations. For liquefied
petroleum gas, reduce pipe diameter one size, but
maintain a ½ inch (13mm) minimum diameter.
2. Check supply pressure and local code requirements
before preceding with work.
3. Pipe fittings must be considered when determining
gas pipe sizing.
4. For propane gas: Reduce pipe diameter one size, but
maintain a ¾ inch (19mm) minimum diameter.
Table 4. Natural Gas and Propane,
Pipe Size Requirements.
2G. Gas Supply and Piping
2G-1. General Instructions
Review the following instructions before
continuing the installation.
1.
Gas piping installation must be in accordance
with the latest edition of ANSI Z223.1. In
Canada, the installation must be in accordance