5. Disassemble loose pipe fittings. Clean and cement using
same procedures as used for system piping.
6. Check required dimensions as shown in Fig. 38 or 39.
E.
Multiventing and Vent Terminations
When 2 or more 352MAV furnaces are vented near each other,
each furnace must be individually vented. NEVER common vent
or breach vent 352MAV furnaces. When 2 or more 352MAV
furnaces are vented near each other, 2 vent terminations may be
installed as shown in Fig. 43, 44, 45, 46, or 47 but the next vent
termination must be at least 36 in. away from first 2 terminations.
It is important that vent terminations be made as shown to avoid
recirculation of flue gases. Dimension A in Fig. 43, 44, 45, 46, and
47 represents distance between pipes or rain shields, as touching or
2-in. maximum separation.
X.
CONDENSATE DRAIN
CAUTION:
UNIT MAY NOT OPERATE
Failure to follow this caution may result in intermittent
unit operation.
Unit must not be installed, operated, and then turned off
and left in an unoccupied structure during cold weather
when temperature drops to 32°F and below unless drain
trap and drain line have adequate freeze protection. See
Service and Maintenance Instructions for winterizing
procedure. (See Fig. 42.)
A.
General
Condensate trap is shipped installed in the blower shelf and factory
connected for UPFLOW application. Condensate trap must be
RELOCATED for use in DOWNFLOW and HORIZONTAL
applications.
Condensate trap MUST be used for all applications.
An external trap is not required when connecting the field drain to
this condensate trap.
The field drain connection (condensate trap or drain tube coupling)
is sized for l/2-in. CPVC, 1/2-in. PVC, or 5/8-in. ID tube
connection.
Drain pipe and fittings must conform to ANSI standards and
ASTM D1785, D2466 or D2846. CPVC or PVC cement must
conform to ASTM D2564 or F493. Primer must conform to ASTM
F656. In Canada, use CSA or ULC listed schedule 40 CPVC or
PVC drain pipe, fittings, and cement.
When a condensate pump is required, select a pump which is
approved for condensing furnace applications. To avoid conden-
sate spillage, select a pump with an overflow switch.
Furnace condensate is mildly acidic, typically in the pH range of
3.2 to 4.5. Due to corrosive nature of this condensate, a condensate
pH neutralizing filter may be desired. Check with local authorities
to determine if a pH neutralizer is required.
B.
Application
The furnace, A/C, and humidifier drains may be combined and
drained together. The A/C drain must have an external, field-
supplied trap prior to the furnace drain connection. All drain
connections (furnace, A/C, or humidifier) must be terminated into
an open or vented drain as close to the respective equipment as
possible to prevent siphoning of the equipment’s drain.
See Fig. 48 for example of possible field drain attachment using
1/2-in. CPVC or PVC tee for vent and A/C or humidifier drain
connection.
Outdoor draining of the furnace is permissible if allowed by local
codes. Caution should be taken when freezing ambient may freeze
drain pipe and prohibit draining.
WARNING:
PERSONAL INJURY HAZARD
Failure to follow this warning could result in property
damage and personal injury or death.
Caution should be taken to prevent draining where
slippery conditions may cause personal injuries. Exces-
sive condensate draining may cause saturated soil condi-
tions which may result in damage to plants.
C.
Condensate Drain Protection
Freezing condensate left in condensate trap and drain line may
cause cracks, and possible water damage may occur. If freeze
protection is required, use condensate freeze protection accessory
or equivalent 3 to 6 watt per ft at 120-v and 40°F self-regulating,
shielded, and waterproof heat tape. See Installation Instructions
supplied with accessory or heat tape manufacturer’s recommenda-
tions.
1. Fold heat tape in half and wrap on itself 3 times.
2. Locate heat tape between sides of condensate trap back.
(See Fig. 49.)
3. Use wire ties to secure heat tape in place. Wire ties can be
positioned in notches of condensate trap sides. (See Fig.
49.)
4. Wrap field drain pipe with remaining heat tape, approxi-
mately 1 wrap per ft.
5. When using field-supplied heat tape, follow heat tape
manufacturer’s instructions for all other installation guide-
lines.
START-UP ADJUSTMENT AND SAFETY CHECK
CAUTION:
UNIT MAY NOT OPERATE
Failure to follow this caution may result in intermittent
unit operation.
Furnace control must be grounded for proper operation,
or control will lock out. Control is grounded through
green/yellow wire connected to gas valve C-terminal and
burner box screw.
I.
GENERAL
The furnace must have a 115-v power supply properly connected
and grounded. Proper polarity must be maintained for correct
operation.
NOTE:
Proper polarity must be maintained for 115-v wiring. If
polarity is incorrect, control status indicator light will flash rapidly
and the furnace will not operate.
Natural gas service pressure must not exceed 0.5 psig (14-in. wc),
and no less than 0.16 psig (4.5-in. wc).
Thermostat wire connections at R and W/W1 are the minimum
required for gas heating operation. W2 must be connected for
2-stage heating thermostats. C
OM
, Y/Y2, and G are required for
cooling, heat pumps, and some clock thermostats. These must be
made at the 24-v terminal block on the control. (See Fig. 32.)
This furnace can be installed with either a single-stage heating or
a 2-stage heating thermostat.
For single-stage thermostats, connect thermostat W to W/W1 at
furnace control terminal block. (See Fig. 27.) For single-stage
thermostats, the control will determine, based on length of previ-
ous heating on and off cycles, when to operate in low- and high-
gas heat for optimum comfort. Setup switch-1 (SW-1) must be in
the factory-shipped OFF position. See Fig. 31 and Table 9A and
9B for setup switch information.
If a 2-stage heating thermostat is to be used, move SW-1 to ON
position at end of furnace installation. This overrides built-in
control process for selecting high and low fire and allows the
2-stage thermostat to select gas heating modes. The W2 from
thermostat must be connected to W2 on control terminal block.
(See Fig. 28 and Fig. 52A-G.)
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