LAARS Mighty-Stack TL80-199 - Installation, Operation and Maintenance Instructions - Manual (Page 6)

LAARS Heating Systems Company
Page 6
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.
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.
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 gas valve 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 requirements 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)
inches kPa inches 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.
Figure 5. Gas Supply Piping.