A.O. Smith 520 Direct Vent Indoor, Service Manual

Page: 8 / 97

520 Indoor / 520 Outdoor Service Manual
Ver. 1.00
8
CONFIDENTIAL
4. List of main components in the interior view
No. Description
Item# in
components
diagram
AOS Part #
Common parts
For other models
1
Manifold assembly with
gas valve assembly
118
319143-046 (LP model)
319143-047 (NA model)
2 Computer board 701 319143-126
3 Igniter 123 319143-052 110, 310, 510, 910, 710
4 Transformer 702 319143-127 910
5 Water inlet 411 319143-074 710
6 Water outlet 435 319143-098 710
7 Mixing thermistor 418 319143-081 710
8 Inlet thermistor 422 319143-085 510, 910, 710
9 Output thermistor 433 319143-096 510, 910, 710
10 Overheat cut-off fuse 404 319143-067
11
Burner assembly
(Burners)
101 319143-030
12 Hi-limit switch 432 319143-095 510, 910, 710
13 Fan motor 114 319143-043
310 Indoor, 510 Indoor,
910, 710
14
Freeze protection
thermostat
704
319143-129
(520 Indoor)
719
319143-144
(520 Outdoor)
15 Flow sensor 429 319143-092 910, 710
16
Primary heat exchanger
assembly
401
319143-064
(510 Indoor)
456
319143-118
(510 Outdoor)
17 Gas inlet 121 319143-050 110, 310, 510
18 Pipe heater 426 319143-089
19 Water control valve 423 319143-086 910, 710
20
Secondary heat
exchanger
446 319143-108