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Natco Fire-Coil Volume Water Heaters
2G. Gas Supply and Piping
2G-1. General Instructions
Review the following instructions before
continuing the installation.
WARNING
The conversion of heaters from natural gas to
propane gas, or propane to natural, must be done
by a professional service technician. Natco provides
kits and detailed instructions for converting the
heater. Changing burner and/or pilot orifices is
prohibited. The installer must add and sign a gas
conversion tag when the conversion is made.
1.
Gas piping installation must be in accordance
with the latest edition of ANSI Z223.1. In
Canada, the installation must be in accordance
with CAN1-B149.1 or .2 and all local codes that
apply.
2.
Check the rating plate to make sure the heater is
fitted for the type of gas being used. Natco
heaters are normally equipped to operate below a
2000 foot (609 m) altitude. Heaters 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 5 should be used to size the
gas piping from the gas meter to the heater.
Distance from Gas Meter
0-100 feet
100-200 feet
(0-30 m)
(30-60 m)
Heater
Nat.
Size
in.
mm
175
1.00
25
1.25
250
1.25
32
1.25
325
1.25
32
1.50
400
1.25
32
1.50
Notes:
1. These numbers are for natural gas (0.65 Sp. Gr.) and
are based on 1/2 inch (13 mm) water column pres sure
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 1/2 inch (13 mm) 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 mc size, but
maintain a 3/4" (19mm) minimum diameter
Table 5. Natural Gas and Propane
Pipe Size Requirements.
200-300 feet
(60-90 m)
Nat.
Nat.
in.
mm
in.
mm
32
1.25
32
1.50
38
1.50
38
2.00
MANUAL SHUT-OFF
GAS
SUPPLY
INLET
Figure 23. T-Fitting and sediment trap.
5.
Install a sediment trap (drip leg) ahead of the gas
controls (see Figure 23 ). Fit the trap with a
threaded cap which can be removed for cleaning.
6.
Install a manual gas shutoff valve for service and
safety. Check the local codes.
7.
Disconnect the heater and its individual shutoff
valve from the supply gas system during pressure
test of the system at pressures higher than 1/2 psi
(3.4 kPa).
8.
Gas supply pressures to the heater are listed in
Table 6.
Supply Pressure
Water Column
Minimum
Maximum
Table 6. Gas Supply Pressure Requirements.
32
38
NOTE: The heater and all other gas appliances
38
sharing the heater gas supply line must be firing at
51
maximum capacity to properly measure the inlet
supply pressure. Low gas pressure could indicate
an under-sized 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.
VALVE
T-FITTING
3" (76 mm)
MIN.
NIPPLE
CAP
Natural Gas
in.
mm
6.5
165
(see rating plate)
9
229
Page 13
UNION
TO
BOILER
INLET
Propane Gas
in.
mm
11
279
14
356
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