Part No. 4801-1020 Rev 2-2015
Super-Saver XL 250 Heater
– 120 Volt, 60Hz, ETL
Page
15
of 22
b
Gate
valve
Arbitrary Piping System
a
c
d
e
f
g
Heaters
Heaters
30
m
8
m
Gas meter
8
m
tees
10. Pipe Sizing Guidelines
10.1 Calculating HVR & ELOP
1.
Using a system schematic, label each piping
section of the system starting at the meter or
regulator. A different pipe section starts
where the gas demand of the system
changes, usually at a junction.
2.
Determine the Heating Value Required
(HVR) in BTUH (BTU's per hour) for each
section of pipe.
HVR = (no. heaters supplied by pipe
section) X (heat output per heater)
3.
Determine the Equivalent Length Of Pipe (ELOP)
required for sufficient gas service.
ELOP = (length from meter to most remote heater)
+ (Minor loss equivalents of the system)
IMPORTANT: Use the ELOP value from this
equation for size determination of all pipe sections.
4.
Use the ELOP value from step 3, and the HVR of
each pipe section to determine the required pipe size
for either natural gas (NG) (Table 1) or liquid propane
(LP) (Table 2) from the table 'Maximum Capacity Of
Pipe'.
10.2 Directions for Reading Pipe Size from Tables:
EXAMPLE: Four 40,000 BTUH (12 kW) heaters will be installed on the gas pipe line in the 'Arbitrary Piping System'
diagram below. NOTE: Values given in English and Metric equivalent units.
1. Determine the HVR value for each pipe section of the system.
Pipe Section
No. Of Heaters
HVR Calculation
HVR Value
BTUH
kW
BTUH
kW
a-b
4
4 x 40,000
4 x 12
160,000
48
b-c
2
2 x 40,000
2 x 12
80,000
24
c-e
1
1 x 40,000
1 x 12
40,000
12
b-d
1
1 x 40,000
1 x 12
40,000
12
b-f
1
1 x 40,000
1 x 12
40,000
12
c-g
1
1 x 40,000
1 x 12
40,000
12
2. Determine the ELOP. Length from meter to most remote heater = length from a to e (or g) = 100ft (30m) + 25ft
(8 m) = 125ft (38 m) Minor loss equivalents from Table 1 = 1 gate valve x 2ft/valve (1 m/valve) + 3 tees x 11
ft/tee (4 m/tee) =35ft (13 m). Calculated ELOP = 125ft (38 m) + 35ft (13 m) = 160 ft (51 m) Tabulated ELOP =
200ft (60 m) Round up to the nearest table value.
3. In the appropriate table, NG (Table 2) or LP (Table 3), select the column showing the ELOP or the next longer
length, if the table does not give the exact length. Use this column to compare table values to the HVR values.
Use the Natural Gas table (Table 2) in this
example. From step 2, ELOP = 200ft (60 m)
Locate the column labeled 200ft (60 m) in Table 2.
4. Select a pipe section and read down the ELOP
column to find the maximum gas capacity that
matches the HVR for that particular pipe section.
If the exact value is not listed, choose the next
larger value in the column. In this example, start
with pipe section c-e. For pipe section c-e, HVR =
40,000 BTUH (12 kW). From Table 2, column 200
ft, 40 (12) is not listed (NOTE: The table values
are in thousands of BTUH's). The next larger
value of 72 (21) is read from the table,
corresponding to 72,000 BTUH (21 kW).
5. Follow the row leftward until you reach the
columns labeled 'Internal Diameter' and 'Nominal
pipe size'. Read the pipe size for the particular
pipe section. For example, for pipe section c-e,
the pipe size is ¾ inch (0.824 in.) (19.1 mm).
Repeat for each pipe section.
