Midco 400B-33 - Manual (Page 4)

FIGURE 4 Location for Barometric Draft Regulators
Figure 3 and 4: Copyright by the
American Gas Association.
Used by permission of the copyright holder.
V ELECTRICAL
Installation wiring and grounding to the burner must
conform to local codes, or, in their absence in the United
States to National Electric Code, ANSI/NFPA No. 70-
1990, or latest edition; in Canada, to Canadian
Electrical Code Part 1, CSA Standard C22.1.
■ ■ Use copper wire not less than 14 gage for line voltage
wiring. Hook up to a dedicated line with an on-off
disconnect switch and a minimum 3 Amp fuse.
■ ■ The frame of the burner should be well grounded.
Normally the piping and/or electric conduit will provide
sufficient grounding. However, a ground lug is located in
control box used for positive grounding where insulated
pipe couplings are used or where any doubt exists
regarding grounding sufficiency.
■ ■ Confirm that the polarity is correctÑhot wire to strip
terminal L1, neutral L2Ñand that the neutral line is not
subject to induced low voltage (check L2 to earth
ground) from other equipment, as that can cause the
electronic control to malfunction.
■ ■ Each installation must include suitable limit control(s).
Existing oil burner combination operating and limit
controls are normally NOT SUITABLE for gas burner
use.
CAUTION: Label all wires prior to disconnection
when servicing controls. Wiring errors can cause
improper and dangerous operation. Verify proper
operation after servicing.
VI PIPING
CAUTION: The available gas pressure should be
within the limits shown in SPECIFICATIONS section.
Excessive pressure will damage Combination Valve,
Regulator and manual valves. If the supply pressure
exceeds the 14.0" W.C. maximum, a suitable
intermediate main regulator must be installed ahead
of the Main Manual Shut-Off Valve shown in Figure 5.
■ ■ 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 malleable 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 5.
■ ■ Use pipe joint compound approved for use with Liquid
Petroleum Gases.
■ ■ Piping must comply with local codes.
■ ■ To obtain the maximum firing rate of 400 MBH, the
NATURAL gas supply piping must be sized to provide a
minimum of 5.0" W.C. pressure (11.0" W.C. PROPANE)
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 testing, it is
recommended that all low pressure (14.0" W.C. max.)
components, both main and pilot, be disconnected
during testing. Exposing low pressure regulators
and valves, including manual valves, to pressures
over 1/2 PSIG (14" W.C.) will cause damage 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 limitation, be sure to carry out the general
arrangement shown in Figure 5. Install the combination
valve in any position except up-side down.
■ ■ When the burner is installed in jacketed equipment, if
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.
NOTE: If there is more than 1.0" W.C. differential in the
inlet pressure to the burner compared to when all other
gas utilization equipment are off, refer to Section IX.
Capacities shown are for a total pressure drop of 0.3"
W.C. For 0.5" W.C. pressure drop, multiply capacity
shown by 1.3 For higher permissible pressure drops,
consult fuel supplier.
TABLE 2: Supply Pipe Capacities in MBH
VII MAIN GAS SPUD SELECTION
Burners are approved for use with NATURAL or
PROPANE gas and should be used only with the gas
specified on the rating plate.
■ ■ The gas input should be set at the heating rate
determined by the building heat loss and/or heating plant
survey, but not exceeding the rated maximum input of
the heating appliance or burner.
■ ■ 400B burners are shipped equipped for natural gas,
with the spud 11/32" (.343) installed. Compare the gas
input required with the spud capacities shown in the spud
table and, if necessary, install the spare spud (see Figure 7).
PIPE SIZE
3/4
1
1-1/4
1-1/2
TYPE OF GAS
PROPANE
NATURAL
PROPANE
NATURAL
PROPANE
NATURAL
CAPACITY-MBH
LENGTH OF PIPE
15
400
400
30
250
250
400
400
45
200
200
350
400
400
90
250
300
400
400
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