Reznor YDSA Unit Installation Manual - Manual (Page 55)

Form I-Y, P/N 273646R6, Page 55
* Heat sections with dual furnaces. When only one size is listed, both furnaces are the same size and two identical high pres-
sure switches are used. Dual furnace heat sections with electronic modulation Option AG74 have one low pressure switch .
A proprietary electronically controlled venter system provides the required volume of
combustion air and correct gas pressure to maintain thermal efficiency during periods
of modulation. Change of venter speed is controlled by an electronic board located in
the heat section.
The venter system always operates at high speed during pre-purge and post-purge
periods. Speed selection occurs after there is a call for burner ignition.
Two-Speed Venter
System
Location of Combustion
Air Inlet Openings and
Vent Outlets
Vent location depends on the type of gas heat section. Refer to FIGURE 27A, shown
below or FIGURES 28A & 28B, page 56 for vent outlet locations and installation
requirements that apply.
The combustion air inlet openings are located in the doors on the control end of the
unit. Keep all openings clean and free of obstructions.
Vent Temperature Limit
Switch
All furnaces in the high-efficiency gas heat section are equipped with a temperature
activated, manually reset switch to limit the temperature of the vent gases to below
145°F. The switch is attached to the side of each venter housing (single heat sections
have one; dual heat sections have two). See location in FIGURE 25, page 52.
If the setpoint is reached, the switch will activate to interrupt the electric supply to the
gas valve. If the vent temperature switch is activated, identify and correct the cause
before resetting the switch. Refer to the Maintenance Section in Form O-Y for informa-
tion on probable causes and instructions on resetting the switch.
Venting a Standard
(non-condensing) Gas
Heat Section
A unit with a standard efficiency
(non-condensing) heat section
has a vent outlet box as shown
in FIGURE 27A on the left.
If an extension is required, see
Option CC3 or CCD3 below.
Control End of Unit
Optional Gas
Heat Section
Control Access
Condenser
Section
Combustion Air intake
Openings in Doors
(applies to all gas heat
sections)
Single Vent Outlet Box
on a unit with a standard
efficiency (non-
condensing) gas heat
section with either
single or dual furnaces.
FIGURE 27A - Vent
Outlet and Combustion
Air Inlet Locations
Vertical Vent Extension,
Option CC3 or CCD3
- applies to standard
(non-condensing) gas-
fired heat section
If local code requires 4-ft (1.2M) vertical clearance between the flue outlet and the
fresh air intake of the heating system or the building, install a vertical vent with a vent
cap. The option package includes the vent cap. The vent pipe is field supplied. The
vent pipe must be the same diameter as the vent connection.
Remove the cover on the side of the unit to attach the field-supplied vent pipe.
Venting a High-Efficiency (condensing) Gas Heat Section
The high-efficiency heat section vents through a Schedule 40 PVC pipe that extends
from the unit in the locations shown in FIGURE 28A shown on page 56. The vent must
be terminated with a field-provided 45° elbow of Schedule 40 PVC or CPVC vent pipe.
NOTE: In Canada, all PVC vent pipe must be approved to ULC S636.
Attach the 45° elbow at each vent outlet in the orientation illustrated so that the flue
products are directed downward. ( NOTE: Elbow(s) must be 45°.)
Combustion Air Switches for Above 6000 ft. (1830 m) - (cont’d)
Heat
Section
Option
Heat
Size(s)
(Btuh)
High Pressure Switch
Heat
Section
Option
Heat
Size(s)
(Btuh)
High Pressure Switch
Setpoint
Off
Label
Color
Switch
P/N
Setpoint
Off
Label
Color
Switch
P/N
Negative Pressure (iwc) Negative Pressure (iwc)
H175*
75,000 1.35 Green 273554
G372* 150,000
1.35 Green 273554
100,000 1.35 Green 273554 225,000 1.35 Green 273554
H200 200,000 1.35 Green 273554 G452* 225,000 1.35 Green 273554
H202* 100,000 1.35 Green 273554 G452* 225,000 1.35 Green 273554
H300 300,000 1.45 Orange 273555
G525
225,000 1.35 Green 273554
H400 400,000 1.45 Green 273555 300,000 1.25 Blue 273553
H402* 200,000 1.35 Green 273554 G602 300,000 1.25 Blue 273553
H502*
200,000 1.35 Green 273554
300,000 1.45 Orange 273555