LAARS Mighty-Stack TL80-199 - Installation, Operation and Maintenance Instructions User 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.

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*

1.5

2.7

Maximum Supply

Pressure**

2.5

3.4

Manifold Gas

Pressure

1.0

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.