Design and Installation Guide - CT.gov

Section 3: System Configuration
3.2.11 Example 10 - Commercial Elevated Pressure Series System – 2PSI
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August 2010
Figure 3-18 below shows a typical commercial rooftop installation with four (4) appliances. The piping is arranged in series
with a main run branching at the appliances. The utility company’s supply pressure (downstream of the meter) is 2psi. The
utility company advises that the specific gravity of the gas delivered will be 0.60 and the energy content is 1 CFH = 1000
BTUH. The 2psi line pressure chart with a pressure drop of 1psi can be used. This will supply the regulators with the 1psi
inlet pressure required for full capacity flow.
Fig. 3-18
Table 3-11
Section Description Load Delivered by Section Section Length Run Length Tube Size
“A” – Trunk 1250 CFH = 1,250,000 BTUH 15 feet 60 feet 1-1/4" CSST
“B” – Trunk 1000 CFH = 1,000,000 BTUH 15 feet 60 feet 1" CSST
“C” – Trunk 750 CFH = 750,000 BTUH 15 feet 60 feet 1" CSST
“D” – Air Handler 500 CFH = 500,000 BTUH 15 feet 60 feet 1" CSST
“E” – Make-Up Air Unit 250 CFH = 250,000 BTUH 10 feet 25 feet 1/2" CSST
“F” – Make-Up Air Unit 250 CFH = 250,000 BTUH 10 feet 55 feet 1/2" CSST
“G” – Make-Up Air Unit 250 CFH = 250,000 BTUH 10 feet 40 feet 1/2" CSST
Run Length for Trunk Sections = Distance from meter to furthest appliance (Longest Run)
Run Length for Appliance Sections = Distance from meter to each appliance
SIZING RUN “A”
Run “A” is sized by the total load of all appliances and the run length from the meter to the furthest appliance
The total load of all appliances is 250 + 250 + 250 + 500 = 1250CFH
The run length to the Air Handler (furthest appliance) is 15 + 15 + 15 + 15 = 60ft
Referring to Table 7-10 (2psi line pressure, 1psi pressure drop): for a 60ft run, 1-1/4" CSST has a capacity over 1250CFH
(actual: 1838)
Gastite Division
603 Hendee Street / Springfield, MA 01104
800.662.0208 / www.gastite.com / gastite@gastite.com