Page 8
507656-01 7/2018
5. Table 2 lists the range of air volumes and equivalent
draft gauge readings for this unit. Observe the draft
gauge reading. If the reading is below the required air
volume, increase the blower speed; if the reading is
above the required air volume, decrease the blower
speed. Refer to the furnace wiring diagram for blower
speed settings.
6. When the required draft gauge readings are obtained,
remove the draft gauge lines and insert snaphole
plugs into the test holes.
Table 2. Air Volume/Static Pressure Drop
Across Coil
Cabinet
Vol: CFM
Drop: in. w.g.
CH35
Model
Width in.
Dry
Wet
-18A-2F
14-1/2
600
.09
.11
-24A-2F
-24B-2F
14-1/2
17-1/2
800
800
.15
.09
.19
.11
-30A-2F
-30B-2F
14-1/2
17-1/2
1000
1000
.24
.14
.27
.16
-36A-2F
-36B-2F
-36C-F
14-1/2
17-1/2
21
1200
1200
1200
.30
.16
.15
.39
.21
.18
-42B-2F
-42C-2F
14-1/2
17-1/2
1400
1400
.26
.18
.31
.21
-48B-2F
17-1/2
1400
.25
.29
-48C-2F
21
1600
.27
.30
-51C-2F
21
1600
.25
.29
-60D-2F
24-1/2
2000
.24
.30
Maintenance
CLEANING THE COIL
The coil should be inspected twice each year and cleaned
at least once per year or more, if necessary. Indoor coil
cleaning should be performed by a licensed professional
service technician (or equivalent).
CAUTION
A damaged coil fin can affect equipment operation and
performance. Do not use flame, high-pressure water,
steam, or volatile cleaners on fins or tubing surfaces. If
cleaning requires the use of acidic or alkaline cleaners,
follow the manufacturer's instructions. Thoroughly flush
cleaner from all equipment components. (Be careful to
prevent damage or corrosion of the components
connected to the system or areas surrounding the
equipment being cleaned.)
Do not use hydrofluoric acid, alkaline, or similar
chemicals to clean coils.
These chemicals are not
necessary to dissolve salt, and may damage the fin
coating. Acid washes are used to dissolve oils and
greases, which generally are not present on residential
applications.
Do not use alkaline washes.
Alkaline washes are useful
for dissolving oxides such as zinc oxide, aluminum oxide,
and iron oxide (rust). However, these three oxides are
more corrosion resistant than base metals, so dissolving
or removing them will cause an increase in corrosion.
1.
Before beginning this or any other maintenance,
turn off all power to the indoor unit at the main unit
disconnect switch.
It is also recommended that you
wear personal protective gear: safety glasses and/or
a face shield, waterproof clothing and gloves.
2. Remove the coil from the indoor unit cabinet, and take
the coil to a place that is appropriate for cleaning it.
3. Vacuum or brush the coil to remove matted and
surface debris from the fins (dirt, hair, etc.). Use
vacuum attachments and /or brushes that will not
damage the coil fins.
4.
Use only clean potable water to clean the coil.
Clean the coil from top to bottom.
NOTE
- For units in coastal regions, fresh water will
dissolve away any salt deposits. (Wash coils with fresh
water at least every six months.)
NOTICE !
Failure to follow instructions will cause damage to
the unit.
This unit is equipped with an aluminum coil. Alu
minum coils may be damaged by exposure to solu
tions with a pH below 5 or above 9. The aluminum
coil should be cleaned using potable water at a
moderate pressure (less than 50psi). If the coil can
not be cleaned using water alone, Lennox recom
mends use of a coil cleaner with a pH in the range of
5 to 9. The coil must be rinsed thoroughly after
cleaning.
In coastal areas, the coil should be cleaned with
potable water several times per year to avoid corro
sive buildup (salt).
5. Spray the coil at a vertical angle of 30 to 45 degrees
with a constant stream of water at moderate pressure
(less than 50 psig). A pressure washer with a fan
nozzle will work best. Do not spray the coil from a
horizontal direction.
6. Direct the spray so that any debris is washed out of the
coil and basepan. For most residential units, hot water
is not necessary.
NOTE
- Attempting to back flush from the inside of the coil
will require removing parts from the unit, and it may be very
difficult to flush the whole coil surface. Attempting to blow
water through a coil will slow the water stream and reduce
the flushing action of the outer fin surface.
7. Replace the coil into the cabinet or plenum. Ensure
that you have followed the proper procedure for
routing and securing the refrigerant tubing.
IMPORTANT
Ensure that the distributor lines are not rubbing together
or kinked. All tubes must have enough clearance from
other metal parts. Use wire ties to secure tubes to
prevent movement that could cause the refrigerant
tubing to fail. Adjust the tubes as necessary.
