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2. Measure the static pressure of the supply duct.
(Positive Pressure)
3. The difference between the two numbers is .4" w.c.
EXAMPLE:
static reading from return duct = -.1" w.c.
static reading from supply duct = .3" w.c.
total external static pressure on this system = .4" w.c.
NOTE: Both readings may be taken simultaneously
and read directly on the manometer if so desired.
If an air conditioner coil or Electronic Air
Cleaner is used in conjunction with the furnace,
the readings must also include these components,
as shown in the following drawing.
4. Consult proper tables for the quantity of air.
If the total external static pressure exceeds the maximum
listed on the furnace rating plate, check for closed dampers,
registers, undersized or poorly laid out duct work.
Checking Static Pressure
Filters - Read This Section Before Installing
The Return Air Ductwork
Filters must be used with this furnace. Discuss filter
maintenance with the building owner. Filters do not ship with
this furnace, but must be provided by the installer. Filters
must comply with UL900 or CAN/ULCS111 standards.
Damage or repairs due to the installation of the furnace
without filters is not covered under the warranty.
Upright Installations
Depending on the installation and/or customer preference,
differing filter arrangements can be applied. Filters can be
installed in the central return register or a side panel external
filter rack kit (upflows), or the ductwork above a downflow
furnace. As an alternative, a media air filter or electronic air
cleaner can be used as the primary filter.
Digital
Manometer
Figure 10
Horizontal Installations
Filters must be installed in either the central return register
or in the return air duct work.
Circulation Air Filters
Upflow Upright
Figure 11
Counterflow
Figure 14
Right Air Discharge
One of the most common causes of a problem in a forced
air heating system is a blocked or dirty filter. Circulating air
filters must be inspected monthly for dirt accumulation and
replaced if necessary. Failure to maintain clean filters can
cause premature heat exchanger failure.
A new home may require more frequent replacement until all
construction dust and dirt is removed.
15
Side/Bottom
Return Duct Option
Figure 12
Figure 13
Upflow Horizontal
Figure 15
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