11
ATH15-501.0 (
Supplement to ATH15-500.10
)
1
3
5
11
13
9
10
2
12
4
5
3
14
13
9
2
4
11
10
Figure 11.1 - Gas Heat Option Gas Controls - C-Cabinet Sized Units
81% Efficiency Option
(Digit
18 = J, K, L
or M)
90% Efficiency Option
(Digit
18 =
U or V)
15
1
3
4
13
9
10
Left Furnace
(Secondary)
Right Furnace
(Primary)
8
7
12
GAS HEAT OPTION COMPONENT LOCATION
15
15
1
1
1.
Power exhauster
2.
Maxitrol EXA STAR modulating gas valve
(right-hand furnace only)
3.
Main combination gas valve
4.
High limit control
5.
VB1285 primary furnace control board
(for right-side furnace, but located on left side of cabinet)
6.
Valve state relay to Carel controller (90% furnaces only)
7.
Secondary furnace control board (for left-side furnace)
8.
Direct spark ignition control board (cover removed)
9.
Vent differential pressure proving switch
10.
Direct spark ignitor
(behind control boards on 90% furnaces)
11.
Manifold tee pressure tap (primary furnace only)
12.
Flame sensor (behind #5 on left hand 81% furnaces)
13.
Manifold piping with gas orifices
14.
Condensate drain float switches
15.
Heat exchanger tube drain tray with drain line
(81% furnaces only)
16.
Compartment strip heater/thermostat
(90% furnaces only)
3
4
(behind pipe)
6
7
8
9
10
12
12
13
14
16
Left Furnace
(Secondary)
Right Furnace
(Primary)
