Detroit Radiant Products Company UH Series - Manual (Page 18)

18
UH Series
Refer to Chart 3.2 for natural gas and Chart 3.3 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 3.4. 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 3.2 • Natural Gas Consumption
*Assumes an average heating value of 1050 BTU/SCF and a Specific Gravity of 0.60.
Chart 3.3 • Propane Gas Consumption
*Assumes an average heating value of 2500 BTU/SCF and a Specific Gravity of 1.53.
Chart 3.4 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 Installation Instructions
Model
Manifold
Pressure
(Inches W.C.)
Min. Inlet
Pressure
(Inches W.C.)
Max. Inlet
Pressure
(Inches W.C.)
Gas
Consumption
(CFH)*
Gallons
per hour *
Orifice
Size
Number of
Orifices
UH-30P 10.0 11.0 14.0 12.0 0.33 57 DMS 2
UH-45P 10.0 11.0 14.0 18.0 0.49 57 DMS 3
UH-60P 10.0 11.0 14.0 24.0 0.66 57 DMS 4
UH-75P 10.0 11.0 14.0 30.0 0.82 57 DMS 5
Model
Manifold
Pressure
(Inches W.C.)
Min. Inlet
Pressure
(Inches W.C.)
Max. Inlet
Pressure
(Inches W.C.)
Gas
Consumption
(CFH)*
Orifice
Size
Number
of Orifices
UH-30N 3.5 5.0 14.0 28.6 49 DMS 2
UH-45N 3.5 5.0 14.0 42.9 49 DMS 3
UH-60N 3.5 5.0 14.0 57.1 49 DMS 4
UH-75N 3.5 5.0 14.0 71.4 49 DMS 5