Midco Unipower G-Series - Manual (Page 7)

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■ ■ Two kinds of draft control are acceptable;
an A.G.A. type draft hood as illustrated in
Figure 9, or a barometric damper as shown in
Figure 10. Use of a draft hood is usually limited
to burners with lower range capacities, while a
barometric draft control is suitable for all
capacities. Application should depend on the
requirements of the installation.
■ ■ If a draft hood is used, it should be of the
same size as the vent connector and should be
located higher than the highest part of the
heating appliance flue passage.
■ ■ If a barometric damper is used, it should be
of the double-swing type, which opens freely
outward to afford downdraft protection
irrespective of settings made to the balancing
weights for updraft control. The damper
should be located so it is free to swing
without interference from surrounding
objects so that the velocity pressure of the
flue gases does not interfere with its operation. See Figure 10 for proper installation.
■ ■ When any vent connector passes through a partition the draft control must be located in the same
room as the heating appliance. A device which will automatically shut off gas to the burner in the event
of sustained backdraft is recommended if such backdraft might adversely affect burner operation or if
flue gas spillage might introduce a hazard. If such a device is used, it shall be of the listed type and
installed and adjusted by a qualified service technician in accordance with the manufacturer's
i n s t r u c t i o n s .
■ ■ The burner when installed, must be wired and grounded in accordance with local codes or in the
absence of local codes, with the National Electric Code ANSI/NFPA No. 70-latest edition. In
Canada, refer to CSA Standard C22.1, "Canadian Electrical Code Part 1".
C A U T I O N : Refer to the separate wiring diagram included with each burner.
■ ■ When wiring, be sure that the electrical power take-off is connected to a permanently live circuit and
use multiple 14 gage copper wire conductors. Provide a fused disconnect switch in the burner circuit.
Each installation must include a limit control to guard against excess temperature or steam pressure.
Steam or vapor systems will require a low water cut-off.
■ ■ For the usual low pressure gas supply system, 5" to 14" W.C. NATURAL (11" to 14" W.C. PROPANE)
use Table 3 to find the recommended gas supply line size.
■ ■ Piping follows normal practices and should be connected to the burner in the manner shown in
Figure 11. If the piping must be rearranged because of space limitations be sure to carry out the
sequence of components illustrated. While the pilot regulator can be mounted in any position, the main
regulator should be mounted upright and in a horizontal run of pipe.
■ ■ Run full size pipe or tubing from regulator vent openings to outside of building. Provide no traps in
the vent lines and terminate away from all doors and windows; also make provisions for keeping rain
and foreign objects from entering the vent piping.
Figure 10: Location for Barometric
Barometric Dampers
Figures 9 and 10: Copyright by the
American Gas Association.
Used by permission of the copyright holder.
V Electrical
VI Piping
Figure 11: Piping Connections