Gas Line Sizing Table

What size gas line does a Rinnai Tankless Water Heater require?

Rinnai Tankless Water Heaters are designed to provide maximum performance and efficiency using either a 3/4" or 1/2" gas line, as long as sufficient gas flow is available. An undersized gas line can stress a tankless system and possibly reduce its lifespan, all Rinnai tankless water heaters are equipped with technology that safely ceases operation if they detect an inadequate gas flow. This innovative feature safeguards the unit from compromising performance and efficiency.

The tables below list the maximum length for both 1/2" and 3/4" gas lines when paired with Rinnai Tankless Water Heater models. Note: that Table 1 is intended for Natural Gas and Table 2 is intended for Low-Pressure Propane Gas supplies. 

 

Table 1: Intended for Natural Gas

Rinnai Tankless Water Heater Models

Name Plate Ratings (BTU/H)

SCH 40 Metallic Pipe Size (Maximum Equivalent Length)

1/2 Inch

3/4 Inch

V53e 120,000 100' 450'
V65e, V65i 150,000 70' 300'
RUC80i, RU80i 152,000 70' 166'
RL75i, RL75e 180,000 50' 200'
V75i, V75e 180,000 50' 200'
RLX94i 192,000 40' 175'
RUC98i, RU98e 199,000 40' 175'
RL94i, RL94e 199,000 40' 175'
RUCS65i, RUS65e 130,000 100' 350'
RUCS75i, RUS75e 160,000 60' 250'
RU130i, RU130e 130,000 100' 350'
RU160i, RU160e,  RUR160i, RUR160e 160,000 60' 250'
RU180i, RU180e 180,000 50' 200'
RU199i, RU199e,  RUR199i, RUR199e 199,000 50' 175'
 

Rating is based on 1 Ci. Ft. Nat’l gas = 1,000 BTU

INTENDED USE: Initial Supply Pressure: 8.0" w.c. or greater; Inlet Pressure: <2 psi; Pressure Drop: 3.0" w.c.; Specific Gravity: 0.60

Source: NFPA 54/ ANSI Z223.1 National Fuel Gas Code

 

Table 2: Intended for (Low-Pressure) Propane Gas

Rinnai Tankless Water Heater Models

Name Plate Ratings (BTU/H)

SCH 40 Metallic Pipe Size (Maximum Equivalent Length)

1/2 Inch

3/4 Inch

V53e 120,000 50' 300'
V65e, V65i 150,000 30' 175'
RUC80i, RU80i 152,000 30' 175'
RL75i, RL75e 180,000 20' 125'
V75i, V75e 180,000 20' 125'
RLX94i 192,000 20' 100'
RUC98i, RU98e 199,000 20' 80'
RL94i, RL94e 199,000 20' 80'
RUCS65i, RUS65e 130,000 40' 200'
RUCS75i, RUS75e 160,000 30' 150'
RU130i, RU130e 130,000 40' 200'
RU160i, RU160e,  RUR160i, RUR160e 160,000 30' 150'
RU180i, RU180e 180,000 20' 125'
RU199i, RU199e,  RUR199i, RUR199e 199,000 20' 80'
 

INTENDED USE: Pipe Sizing Between Single- or Second-Stage (Low-Pressure) Regulator and Appliance. Initial Pressure: 11.0" w.c; Pressure Drop: 0.5" w.c.; Specific Gravity: 1.50

Source: NFPA 54/ ANSI Z223.1 National Fuel Gas Code

 

Here are the steps needed to properly size your gas line:

  • Determine what type of gas is being used
  • Determine inlet pressure
  • Determine the allowed pressure drop
  • Determine what other types of gas appliances are sharing the gas line
  • Determine the maximum loads expected on the whole system as stated in the National Fuel Gas Code

NOTE: For complete information on gas sizing for Rinnai Tankless Water Heaters, consult the 'Operations and Installation Manual' that comes with your unit. Or, consult a licensed Rinnai installation professional who can help guide you through the process.

FIND A PRO

Talk to a PRO to learn more or schedule an installation

Find
REGISTER A UNIT

Register your unit to ensure the reliability of your product

Register Now
CONTACT SUPPORT

Speak with a Customer Care agent to ask a question or give us feedback

Contact