Boilers For Use At High Altitude - Dunkirk 90-50 Installation, Operation & Maintenance Manual

The boilers (with the exception of the 90-75 LP product) are factory
equipped for operation at altitudes ranging from 0-10,000 feet above
sea level. No changes to the factory settings are required for instal-
lations from 0-5,000 feet above sea level. For altitudes from 5,000-
10,000 feet above sea level the gas manifold pressure will need to be
adjusted based upon calorific (Btu) value of supply gas (contact local
gas utility or distributor for this value). For specific settings refer to
Table #1 for natural gas applications and Table #2 for LP gas ap-
plications. Instructions on how to adjust the gas manifold pressure
settings are shown in Figures 17 & 18.
Altitude in Ft.
Normal Input (MBH)
Manifold Pressure In W.C.
Orifice
Altitude in Ft.
Normal Input (MBH)
Manifold Pressure In W.C.
Orifice
Altitude in Ft.
Normal Input (MBH)
Manifold Pressure In W.C.
Orifice
++Contact local gas utility or distributor for Btu value of gas.

boilers for use aT HigH alTiTude

TABLE #1: SERIES 90 NATURAL GAS
SERIES 90-50
Stock Factory
Settings 750
0-5,000
50 –
2.5 4
43331094
SERIES 90-75
Stock Factory
Settings 750
0-5,000
75 –
2.5 3.5
43331092
SERIES 90-100
Stock Factory
Settings 750
0-5,000
100 –
2.5 3.5
43331090
6
Note that 90-75 LP applications for 5,000 - 10,000 feet above sea
level will require an orifice change as well as a gas manifold pres-
sure adjustment based upon calorific (Btu) value of supply gas. Refer
to Table #2 for altitude orifice kit part number. For replacing the
orifice refer to specific instructions included with the kit.
Btu Value of Natural Gas++
850 950
5,000-10,000
– –
4 3.5
43331094
Btu Value of Natural Gas++
850 950
5,000-10,000
– –
3.5 2.5
43331092
Btu Value of Natural Gas++
850 950
5,000-10,000
– –
3.5 2.5
43331090
1000 1050
– –
2.5 2.5
1000 1050
– –
2.5 2.5
1000 1050
– –
2.5 2.5