Detroit Radiant Products Company LS3 Series - Manual (Page 37)

37
LS3 Series
Refer to Chart 3.7 for natural gas and Chart 3.8 for propane to determine the cubic feet per hour (CFH)
required for the type of gas and size of unit to be installed. To determine the proper pipe diameter, use the
CFH value and the length of pipe necessary from Chart 3.9. In the case where several units are serviced by
the same main gas line, the total capacity (CFH) and length of main must be adequate to service all
appliances downstream of this main.
Chart 3.7 • Natural Gas Consumption
* Assumes an average heating value of 1050 BTU/SCF and a Specific Gravity of 0.60.
Chart 3.8 • Propane Gas Consumption
* Assumes an average heating value of 2500 BTU/SCF and a Specific Gravity of 1.53.
Chart 3.9 allows for a 0.3 inch W.C. pressure drop in the supply pressure from the building main to the inlet
of the unit. Refer to the chart for the appropriate range of inlet pressures for each gas type. When sizing the
inlet gas pipe diameter, make sure that the unit supply pressure can be met after the 0.3 inch W.C. pressure
drop has been subtracted from the main pressure. If the 0.3 inch W.C. pressure drop is too high, refer to
NFPA 54 or the Gas Engineer’s Handbook for other gas pipe capacities.
3.0 Installation • Gas Supply
Model
Input
Manifold
Pressure
(Inches W.C.)
Minimum Inlet
Pressure
(Inches W.C.)
Gas
Consumption*
(CFH) Orifice Size
LS3-(10,15)-25 25,000 BTU/h 3.5 5.0 23.8 41 DMS
LS3-(10,15)-30 30,000 BTU/h 3.5 5.0 28.6 37 DMS
LS3-(15,20)-40 40,000 BTU/h 3.5 5.0 38.1 31 DMS
LS3-(15,20,30)-50 50,000 BTU/h 3.5 5.0 47.6 29 DMS
Model Input
Manifold
Pressure
(Inches W.C.)
Minimum Inlet
Pressure
(Inches W.C.)
Gas
Consumption*
(CFH)
Gallons
per Hour*
Orifice
Size
LS3-(10,15)-25 25,000 BTU/h 10.0 11.0 10.0 0.27 53 DMS
LS3-(10,15)-30 30,000 BTU/h 10.0 11.0 12.0 0.33 52 DMS
LS3-(15,20)-40 40,000 BTU/h 10.0 11.0 16.0 0.44 1.90 mm
LS3-(15,20,30)-50 50,000 BTU/h 10.0 11.0 20.0 0.55 2.15 mm