Nibe Climate Master RGED Series, Installation Instructions Manual

Page: 42 / 160

42
G. GAS
from the National Fuel Gas Code. Orifice required
at 5000 ft. elevation (4% de-rate per thousand ft):
#42
Orifice required at 8000 ft. elevation (4% de-rate
per thousand ft.): #44
Example: 1050 BTU/ft3 Regional Natural Gas
Heating Value
I / H = Q
25000 / 1050 = 23.81ft3
I = Sea Level input (per burner): 25000
H = Sea Level Heating Value: 1050
Q = 23.81 ft3 Natural Gas per hour.
From the National Fuel Gas Code, (3.5” w.c.).
Orifice required at Sea Level: #43 From the
National Fuel Gas Code,
Orifice required at 5000 ft. elevation (4% de-rate
per thousand ft.): #45
Orifice required at 8000 ft elevation (4% de-rate
per thousand ft): #47
ORIFICE ORDERING INFORMATION
Orifice sizes are selected by adding the 2-digit
drill size required in the orifice part number. Drill
sizes available are 39 through 64; metric sizes
available 1.10mm (-90) and 1.15mm (-91):
Orifice Part Number 62-22175-(drill size)
Example 1:
# 60 drill size orifice required
Part # 62-22175-60
Example 2:
1.15mm drill size orifice required
Part # 62-22175-91
NATURAL GAS ORIFICE SELECTION BASED
ON HEATING VALUE & ELEVATION*
HIGH ALTITUDE
Notes:
1. Furnaces are factory equipped with orifices
sized for 1050 sea level heating value gas.
2. Installer must be aware of the local heating
value (sea level standard) to use the chart below.
3. This chart is based on the National Fuel Gas
Code (NFGC) and based on natural gas with a
specific gravity of 0.60
4. The recommended orifices below allow the
furnace to operate within 10% of design rate.
However, NFGC calculations are the best
method.
5. Furnace operation is optimized when operating
at design rate. Installer is responsible to verify
rate.