Midco DS24A - Manual (Page 5)

VI Piping CAUTION: The available gas
pressure should be within the lim-
its shown in the SPECIFICATIONS
section. Excessive pressure will
damage Combination Valve and
Regulator. If the supply pressure
exceeds the 14.0" W.C. maximum,
a suitable intermediate main reg-
ulator must be installed ahead of
the Main Manual Shut-Off Valve
shown in Figure 6.
■ ■ ■ ■ The burner gas supply piping should
branch off from the main line as close
to the gas meter as possible. Do not
connect to the bottom of a horizontal
section. Use new black pipe and mal-
leable fittings free of cutting and
threading burrs or defects.
■ ■ ■ ■ Provide a sediment trap, union and 1 /
8
" pressure tap in piping close to burner as shown in Figure 6.
■ ■ ■ ■ Use pipe joint compound approved for use with Liquid Petroleum Gases.
■ ■ ■ ■ Piping must comply with local
codes.
■ ■ ■ ■ To obtain the maximum firing
rate of 225 MBH, the NATURAL
and PROPANE gas supply piping
must be sized to provide minimum
of 5.0" W.C. pressure to the inlet of
the Combination Valve when the
burner and all other gas utilization
equipment are on.
CAUTION: Because it is
difficult to accurately control
pressure during supply pipe
leak test, it is recommended that the Combination Valve be disconnected. Exposing the
Combination Valve to a pressure over 1/2 PSIG (14.0" W.C.) will damage the valve and
void all warranties.
DANGER: Explosion hazard.
Do not use oxygen for pressure testing.
An explosion could occur during initial start-up.
■ ■ ■ ■ If the burner piping must be rearranged because of space limitations, be sure to carry out the
general arrangement shown in Figure 6. Install the Combination Valve in any position except up-
side down.
■ ■ ■ ■ When the burner is installed in jacketed equipment, it is recommended that the Combination
Valve be left adjacent to the burner within the vestibule and the Main Manual Shut-Off Valve be
installed outside.
Standard burners are approved for use with NATURAL or PROPANE gas only, and should be used
only with the gas specified on rating plate.
■ ■ ■ ■ A Standard Model DS24A Economite is shipped ready for NATURAL gas. As shipped, it is field
convertible to PROPANE gas, see Table 3.
■ ■ ■ ■ As shipped, the installed NATURAL gas spud has a .218 diameter orifice size for an input
capacity range of approximately 105 to 150 MBH. Spare spuds are included in a spare spud bag
(stamped with inch diameter) for other capacity ranges and/or conversion to PROPANE, see Table 3.
■ ■ ■ ■ The Combination Valve Gas Pressure Regulator is set to provide 2.0" W.C. manifold gas pres-
sure for minimum spud input and the combustion air shutter is set for maximum spud input, 32
turns from full closed to provide a lean gas/air mixture for initial start-up.
■ ■ ■ ■ If a standard NATURAL gas ECONOMITE DS24A is to be used with PROPANE gas, affix the
PROPANE label from the spare spud bag over the NAT designation on the rating plate and install
the appropriate size main spud as detailed below.
■ ■ ■ ■ If the required firing rate does not fall within the range of the installed spud, or if converting to
PROPANE gas, select the correct capacity range from Table 3 and if so indicated, the spud with
the correct orifice size (stamped with inch diameter) from the spare spud bag. If the required fir-
ing rate is at the minimum of a capacity range, select the next lower range spud.
■ ■ ■ ■ To change the main spud, turn off the Main Manual Shut-Off Valve and burner power, remove
the backplate, disconnect the factory installed union located between Combination Valve and
manifold slide plate and pull out curved manifold pipe. Unscrew the installed main spud from the
end of the curved manifold pipe and install the selected main spud, making sure to reuse the
fiber spud gasket. Reassemble burner in reverse order.
Pipe
Size
1 /
2
3 /
4
1
1 1 /
4
130
200
225
90
145
190
225
60
100
130
205
225
50
80
105
165
195
60
80
125
150
225
225
Type
of Gas
NATURAL
PROPANE
NATURAL
PROPANE
NATURAL
PROPANE
NATURAL
Approx. Capacity-MBH
Length of Pipe
Table 2: Supply Pipe Capacities in MBH
5
10 20 40 60 100
Figure 6: Piping Connections
VII Main Gas Spud