Gas Supply Piping - Takagi 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. Right volume gas
supplies to system can be expect full performance. 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. First determine the effective length of
the gas supply line by measuring the actual length of
piping, and then adding 5 ft. for every elbow or "T" to
the actual length. Use the charts below to determine
the pipe diameter necessary to accommodate the BTU
demand of the unit.
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
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
If there is more gas drawing
Min. 5" WC
Max. 10.5" WC
Min. 11" WC
Max. 14" WC
Natural Gas Supply Piping
Based on 0.60 specific gravity for natural gas at .5" WC pressure drop
DOE standard is 1100 BTU per cubic ft. 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.
Cubic Feet of Natural Gas
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
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