15
iN401 - iN501 Gas
Connection
May
2019
-
Revision
00
4. When multiple units are connected use a dedicated gas
pressure regulator for each unit.
5.
To convert the unit to propane, refer to the Propane
(LPG) Conversion section in this manual. For additional
information refer to “11. Natural Gas to Propane
Conversion” on page 35.
6.4.1 Venting of Gas Supply Regulators
Make sure the gas supply regulator is properly vented by
following all local codes and the gas regulator manufacturer’s
recommendations.
1. The vent pipe must be at least the same size as the
regulator vent.
2. When multiple units are connected, each regulator must
have a separate vent line.
3. Vent lines must not be connected together or connected
with any other appliance requiring external venting.
4. When selecting the size, the pipe diameter must be
increased by one size for every 20 feet of pipe.
a. Each 90° elbow is equivalent to approximately:
4.5 feet for nominal pipe sizes of up to 1-1/2”
10.5 feet for nominal pipe sizes of up to 4”.
b. Each 45° elbow is equivalent to approximately:
2 feet for nominal pipe sizes of up to 1-1/2”
5 feet for nominal pipe sizes of up to 4”.
6.5 Length of Gas Supply Line
1.
Make sure the length supply line is correctly sized.
a. Measure the length of the gas supply line from the
gas meter to the water heater or other appliances
requiring gas. The diameter of the pipe must be in
relation to the length.
b. The total length of gas piping, as well as fitting pressure
drop, must be considered when sizing the gas piping.
Total equivalent length should be calculated from the
meter or source location to the last heater connected.
c. Gas pipe size should be selected on the total
equivalent length. The gas volume for cfh flow will be
the input divided by the calorific value of the fuel to be
supplied.
d. Use the Gas Pipe Sizing tables in this manual or refer
to the gas line manufacturers sizing information to
determine the correct diameter for the supply pipe.
e. The diameter of the gas lines, shown in the illustration,
will vary according to the specific installation
requirements.
6.6 Gas Piping Material
1. All gas piping and components must comply with NFPA
local codes, and utility requirements minimum. Only gas
approved fittings, valves, or pipe should be utilized.
2. Standard industry practice for gas piping is Schedule 40
iron pipe and fittings. All high and low gas pressure piping
systems must comply with local utility and building codes.
3. Assembled piping should be clean of all scale, debris,
metal particles, or foreign material.
4. The piping must be supported from the floor, ceiling, or
walls and by the water heater itself.
6.7 Determine Correct Gas Pipe Diameter
Note:
The water heater should be the first appliance to be
connected to the gas supply line.
1. Determine the gas requirement of the water heater(s)
and other appliances requiring gas.
2. Size the pipe diameter according to the COMBINED total
maximum BTUH volume for all the appliances as if they
were all operating at the same time. Use the “6.10 Gas
Pipe Sizing Tables” on page 17.
3. Select the proper header pipe according to the number of
units being connected together, as shown in the chart.
Header Sizing for Multiple iN Units
Number of
Heaters
1
2
3
4
Sch 40 Iron
Pipe
2”
2”
3”
3”
4. The maximum pressure drop from the source to the final
water heater must not exceed 0.3” W.C.
5. The maximum gas flow rate required is the sum of
the maximum inputs of each unit divided by the heat
of combustion of the fuel supplied at the location,
(approximately 1,030 BTU per cubic foot for natural gas
or 2,520 BTU per cubic foot for propane).
Note:
The fuel supplier or utility should be consulted to
confirm that sufficient volume and normal pressure is
provided to the building at the discharge side of the
gas meter or supply pipe.
6.8 Gas Pipe Drip Leg and Shut-off Valve
1. Install a gas pipe drip leg on each water heater to prevent
dirt, condensation, or debris from entering the gas inlet.
Drip Leg
2. Local codes may require multiple units to have a full size
drip leg on the main gas supply line and one on each unit.
3. The drip leg should have a removable clean-out cap.
4. The gas pipe must not be supported by the drip leg.
5. Following local building codes when selecting and installing
a shut-off valve.
