Form I-RA/D 140/235 (Version A), Page 22
Air Shutter
Check-Test
Continued
WARNING: If there is insufficient draft, it will create
a back pressure resulting in oil fumes in the build
-
ing and/or pulsating when the burner starts and
stops. It may cause excess deposits of soot and
overheat the heat exchanger resulting in premature
failure of the chamber. THIS TYPE OF FAILURE IS
NOT COVERED UNDER THE WARRANTY.
To correct this problem, the height of the chimney may need increased
and/or a UL or CSA/ULC listed draft inducer may be installed.
If a draft inducer is used, a draft proving switch must be installed to
shut off the fuel supply to the burner in the event of the failure of the
draft inducer.
CAUTION: If there is a backdraft or downdraft, do not
continue operation of the heater until the situation is
corrected. Equipment and/or property damage could
result. Back pressure (backdraft or downdraft) may be
caused by the chimney being lower than surrounding
objects, such as buildings, hills, trees, rooftops, etc. It
may be caused by an exhaust fan in the building. The
air intake in the room where the heater is installed must
be of sufficient size so that there is no change in the
draft reading in the flue with the exhaust fan running.
If there is too much draft, it could cause ignition problems, erratic
burner, and loss of thermal efficiency. To correct this problem adjust
the barometric damper to reduce the draft.
Combustion air shutter and
air band settings.
Certain installation conditions may necessitate a
change in these settings. We recommend that the
need for a change be determined by the use of instru-
ments. When obtaining the CO
2
readings, do so with
a hot system that has the correct draft settings. With
a clean heat exchanger, these settings should result
in Bacharach smoke readings not greater than No. 1
and CO
2
reading in the range listed.
IMPORTANT: If it is necessary to change the air
band and air shutter settings, the draft measure
-
ment must be rechecked.
■
Air
Band
Reference Air Shutter and Air Band Settings
Size Air Shutter Air Band
CO
2
Range
140
#1
#1
9.5 - 10.5%
235
#3
#4
10.5 - 11.5%
These are settings
from
which a qualified
serviceman/installer
must make adjustments.
