WHL-001 Rev. 001 Rel. 008 Date 8.23.18
29
water heater has a flanged connection to the swirl plate and blower.
UL recognized fuel gas detectors are recommended in all enclosed
propane and natural gas applications where there is a potential for
an explosive mixture of fuel gas to accumulate. The installation of
these detectors should be made in accordance with the detector
manufacturer’s recommendations, and/or local laws. Failure to
install fuel gas detectors in these applications could result in fire,
explosion, property damage, severe personal injury, or death.
A. Gas Pipe Sizing Tables
1. Gas Pipe Sizing
This information is for reference use only. Refer to gas pipe
manufacturer specifications for actual delivery capacity. The DOE
standard for Natural Gas is 1100 BTU/ft
3
. Contact the local gas
supplier for actual BTU/ft
3
rating.
2. Natural Gas Pipe Sizing
The following table lists maximum capacity of pipe in cubic feet of
gas per hour for gas pressures of 14” or less and a pressure drop of
0.5 inches water column, based on a 0.60 specific gravity for natural
gas.
Pipe Size (in.)
Length of Pipe (Feet)
BTU’s Per
Hour x 1,000
Schedule 40
Metallic Pipe
(0.60 Specific
Gravity,
0.5 WC
Pressure Drop)
10
20
30
40
50
60
80
100
150
200
1/2
172
118
95
81
3/4
360
247
199
170
151
137
117
104
83
1
678
466
374
320
284
257
220
195
157
134
1 1/4
1390
957
768
657
583
528
452
400
322
275
1 1/2
2090
1430
1150
985
873
791
677
600
482
412
2
4020
2760
2220
1900
1680
1520
1300
1160
928
794
3
11300
7780
6250
5350
4740
4290
3670
3260
2610
2240
4
23100
15900
12700
10900
9660
8760
7490
6640
5330
4560
Table 11 - Natural Gas Delivery Capacity - Refer to ANSI Z223.1 - National Fuel Gas Code, Latest Edition
3. LP (Liquid Propane) Gas Pipe Sizing
Contact gas supplier to size pipes, tanks, and 100% lockup gas
pressure regulator. Adjust propane supply regulator provided
by the gas supplier for 14 inches w.c. maximum pressure.
B. Gas Piping Requirements
1. The gas connection fitting on the water heater is 1/2” NPT.
NOTE:
The gas supply pipe size must not be less than 1/2”.
2. The supply line must be sized for the maximum output of
the water heater being installed. If there are additional
gas appliances on the main supply line, size the supply
line for the maximum total COMBINED BTU/Hr draw of the
appliances. This will ensure the supply line is sized to allow
all the appliances to operate at the same time.
3. Measure the length of the gas supply line from the gas meter
to the water heater. The water heater must be installed
downstream of the gas meter to ensure adequate gas supply.
4. Use the table in this manual or refer to the gas line
manufacturer’s sizing information to determine the correct
supply pipe size. Run the gas supply line in accordance with all
applicable codes.
5. The National Fuel Gas Code (NFPA 54) requires that a sediment
trap (drip leg) be installed in the gas line on appliances not so
equipped. The drip leg must be accessible, a minimum of 3” in
length, and not subject to freezing conditions. See Figure 20.
6. A manual gas shut-off valve should be installed in the gas
supply line close to the water heater. Locate and install manual
shutoff valves in accordance with local and state requirements.
7. To facilitate any future maintenance, it is also recommended
that an approved gas union fitting be installed in the supply
line between the shut-off valve and the 1/2” NPT connection
on the water heater.
8. Use a manometer to test the gas pressure to make sure it meets
the minimum standards and does not exceed the maximum
standards of the water heater.
9. Leak test the gas line pipe before placing the water heater in
operation. Only use approved leak detector liquid solutions to
check for leaks. Never use an open flame to check for leaks.
Support gas supply piping with hangers, not by the heater or its
accessories. The heater gas valve and blower will not support the
weight of the piping. Make sure the gas piping is protected from
physical damage and freezing, where required. Failure to follow
these instructions could result in gas leakage, fire, explosion,
property damage, severe personal injury, or death.
Do not use Teflon tape on gas line pipe thread. Use a pipe
compound rated for use with natural and propane gases. Apply
sparingly on male pipe ends, leaving the two end threads bare.
Failure to follow these instructions could result in gas leakage, fire,
explosion, property damage, severe personal injury, or death.
Figure 20 - Gas Connection
