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INSTALLATION - GAS CONNECTIONS
Considerations for Elevation
The standard ratings for Models DBS/DCS are certified for
elevations up to 2000 feet above sea level. Operation at
elevations above 2,000 feet requires ratings be reduced 4% for
each 1000 feet above sea level per ANSI Z223.1. The exception
is for units in Canada, CSA requires that ratings be reduced 10%
for elevations between 2,001 and 4500 feet. The following
instructions are for units that will be installed over 2,000 feet
elevation. If this does not apply, you may skip ahead to the
Electrical Connections section on page 15.
Manifold Pressure Adjustment
The unit manifold pressure is factory set for operation at
elevations up to 2000 feet as follows:
• For Natural Gas units, 3.5" W.C. based on a gas heating value
of 1,050 BTU/ft3.
• For Propane Gas units, 10.0" W.C. based on a gas heating
value of 2,500 BTU/ft³.
For higher elevations, some utility companies may derate the
BTU content (heating value) of the gas provided at altitude to a
lower value to allow certain heating appliances to be used with
no manifold pressure adjustments. For this reason it is necessary
that the supplying utility be contacted for detailed information
about the gas type and BTU content (heating value) before
operating any heater. Table 14.1 shows the standard derated
heating values of natural and propane gases at various
elevations.
Table 14.1
Gas Heating Values at Altitude (Btu/ft³) jkln
Altitude (ft)
Natural Gas
0-2,000
2,001-3,000
3,001-4,000
4,001-4,500
4,501-5,000
5,001-6,000
6,001-7,000
7,001-8,000
8,001-9,000
9,001-10,000
j V alues shown are for 3.5" W.C. manifold pressure for Natural Gas and 10.0"
W.C. for Propane Gas. If the local utility supplies gas with a different Btu/ft³
value, use Equation 14.1 to calculate the required manifold pressure.
k G as heating values shown are derated 4% per 1,000' of elevation (10%
between 2,000' and 4,500' elevation in Canada) in accordance with ANSI
Z223.1 and CSA-B149, respectively.
l 945 Btu/ft³ for Canada
m 2,250 Btu/ft³ for Canada
n W hen installed at altitudes above 2,000', a pressure switch may need to be
changed. Refer to Table 14.2 to determine if a switch change is required.
If the utility is supplying gas with heating values SAME as shown
in Table 14.1, the manifold pressure should remain set to 3.5"
W.C. for natural gas and 10.0" W.C. for propane gas and you
may proceed to the section on this page titled "Selection of the
Proper High Altitude Kit".
If the utility is supplying gas with heating values DIFFERENT
than shown in Table 14.1, use Equation 14.1 to determine the
appropriate manifold pressure for the elevation and gas heating
value being supplied. Note what that value is, as it will be
needed later for Start-Up. Proceed to the section on this page
titled "Selection of the Proper High Altitude Kit".
14
Propane
1,050
2,500
929 l
2,212 m
892 l
2,123 m
874 l
2,080 m
856
2,038
822
1,957
789
1,879
757
1,803
727
1,731
698
1,662
Equation 14.1 - Manifold Pressure for Gas Heating
Values Different Than Shown in Table 14.1
Where:
MP ELEV = Manifold Pressure (" W.C.) at installed
elevation
BTU TBL = BTU/ft³ content of gas from Table 14.1
BTU ACT = BTU/ft³ content of gas obtained from the
utility company
MP SL
= Manifold Pressure (" W.C.), at Sea Level
(use 3.5" W.C. for natural gas and
10.0" W.C. for propane)
NOTE: For units equipped with two-stage or modulating gas
controls, only the high fire manifold pressure needs to be
adjusted. No adjustments to the low fire manifold pressure are
necessary on these units.
Selection of the Proper High Altitude Kit
All units installed at elevations greater than 2000 feet above sea
level require a kit, in addition to potential manifold pressure
adjustment outlined in the previous step. To determine the proper
kit to use, refer to Table 14.2. For more information, refer to the
latest revision of Modine Bulletin 75-530.
Table 14.2 - High Altitude Kit Selection Table jklm
Item Code by Elevation Above Sea Level (ft)
2,001-
Model Size
2,500
75
67248 67248 67248 67248 67248 67248 67248
100
67248 67248 67248 67248 77785 77785 68406
125
67248 77786 77786 77786 77785 77785 68406
150
77787 77786 77786 77786 77785 77785 68406
175
77786 77786 68408 68408 68408 68410 68410
200
67248 67248 67248 67248 67248 67248 67248
225
67248 67248 67248 67248 67248 67248 67248
250/500
67248 67248 67248 67248 67248 67248 67248
300/600
67248 67248 67248 67248 67248 67248 67248
350/700/840 67248 67248 67248 77786 77785 77785 68406
400/800/960 77786 77786 77785 77785 77785 68410 68410
j Applies to both installations in the U.S. and Canada.
k Applies to both natural and propane gas.
l S izes 75-400 require a kit qty. of 1, sizes 500-800 require a kit qty of 2,
sizes 840-960 require a kit qty of 3.
m A ll kits include a High Altitude Conversion Label and Installation Instructions.
Additionally, all kits except 67248 include a Pressure Switch to replace the
standard switch.
If a unit is to be installed at higher elevations AND converted
from natural gas to propane gas operation, a propane conversion
kit must be used in conjunction with the manifold pressure
adjustment and high altitude kit listed above. For the Selection
and Installation Instructions for propane conversion kits, please
see the latest revision of Modine Bulletin 75-511.
5-594.10
2,501-
4,501-
5,001-
5,501-
4,500
5,000
5,500
6,500
6,501-
7,001-
7,000
7,500
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