Gas Supply Piping - Takagi Flash Water Heater T-KD20 Installation Manual And Owner's Manual

Gas Supply Piping

Attention: Proper gas pressure is important but
gas volume is more critical than pressure. With the
right volume of gas supplied to system full
performance can be expected. You may calculate
right gas pipe for right volume supply.
Check the rating plate to make sure that the unit
was built for the type of gas available in the area.
The gas supply piping should be sized according
to the Applicable Plumbing Code for a maximum
draw of 185,000 BTUH.
effective length of the gas supply line by
measuring the actual length of piping, and then
adding 5 ft. for every elbow or "Tee" to the actual
length. Use the charts below to determine the pipe
diameter necessary to accommodate the BTU
demand of the unit. If there is more gas drawing
appliances on the line, size according to the
maximum amount of BTU demand.
The gas supply pressures must be within the
ranges of the following chart:
Natural Gas
Supply Pressure
Propane Gas
Supply Pressure
Based on 0.60 specific gravity for natural gas at .5" WC pressure drop
Pipe
Size
Length 10' 20'
½" 174 119
¾" 363 249
1" 684 470
1 ¼" 1404 965
1 ½" 2103 1445
2" 4050 2784
Pipe
Size
Length 10' 20'
½" 275 189
¾" 567 393
1" 1071 732
1 ¼" 2205 1496
1 ½" 3307 2299
2" 6221 4331
First determine the
Min. 5" WC
Max. 10.5" WC
Min. 11" WC
Max. 14" WC
Natural Gas Supply Piping
DOE standard is 1100 BTU per cubic ft. of natural gas
Cubic Feet of Natural Gas
30' 40' 50'
96 82 73
200 171 152
377 323 286
775 663 588
1161 993 880
2235 1913 1696
Propane Supply Piping
Based on 11" WC supply pressure
30' 40' 50'
152 129 114
315 267 237
590 504 448
1212 1039 913
1858 1559 1417
3465 2992 2646
Insufficient gas supply pressure can cause the
Flash Water Heater to lose efficiency or not work
at all.
WARNING: Fire or explosion may result if the
maximum supply pressures are exceeded.
The manifold gas pressure should be at maximum
2.3" WC for natural gas, and 2.5" WC for propane.
Always use approved connectors to connect the
unit to the gas line. Always purge the gas line of
any debris before connecting to the water heater.
WARNING: Conversion of this unit from natural
gas to propane or propane to natural gas cannot
be done in the field. Contact your local retailer or
distributor to get the correct unit for your gas type.
Always install a manual shutoff valve on the gas
supply line in case of an emergency, or if service
or maintenance is necessary.
This appliance and its individual shut-off valve
must be isolated from the gas supply piping
system by unplugging the unit and turning off the
main gas valve during any pressure testing of the
gas supply piping system at test pressures equal
to or less than ½ PSI.
When all of the connections have been made,
check the gas line for leaks. Apply soapy water to
all gas fittings and connections, if bubbles form,
there may be a leak.
60' 70' 80'
66 61 56
138 127 118
259 239 222
532 490 456
798 734 683
1536 1413 1315
kBTU of Propane
60' 70' 80'
103 96 89
217 196 185
409 378 346
834 771 724
1275 1181 1086
2394 2205 2047
9
90' 100' 125'
53 50 44
111 104 93
208 197 174
428 404 358
641 605 536
1234 1165 1033
90' 100' 125'
83 78 69
173 162 146
322 307 275
677 630 567
1023 976 866
1921 1811 1606
150' 200'
40 34
84 72
158 135
324 278
486 416
936 801
150' 200'
63 55
132 112
252 213
511 440
787 675
1496 1260