Midco Unipower MPG Series - Manual (Page 5)

extend beyond the inner face.
Where two or more appliances
use the same chimney, be sure
not to enter the chimney with
both flue pipes at the same level.
Do not arbitrarily reduce the
vent connector size, since a back
pressure can build up, leading to
possible leakage of flue products
into the room.
Chimney construction can be
either of brick, preferably tile
lined, or of steel. Joints in the
chimney should be smooth and
leak free to prevent
uncontrollable air infiltration. They
should be made so that
condensation if any, will not
collect in the joints or leak to the
outside.
If the vent connector must be
extra long, the area of the pipe
and chimney should be increased
or the chimney height must be
increased, or both. Never allow
the horizontal length of the vent
connector to exceed the height of the chimney.
Two kinds of draft control are acceptable; an A.G.A. type draft hood as illustrated in Figure 5,
or a barometric damper as shown in Figure 6. 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 is free
swinging without interference from surrounding objects so that the velocity pressure of the flue
gases does not interfere with its operation. See Figure 5 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
5
Part 1 Installation
Figure 5: Recommended Locations for Draft Hoods
Note:
Figures 3 and 4 :
Copyright by
American Gas
Association.
Used by
permission of the
copyright holder.
Figure 6: Location for Barometric Draft Regulators
Note: Figures 3 and 4 :
Copyright by American Gas Association.
Used by permission of the copyright holder.
IV Chimney, Vent
Connector and
Draft Control
Continued