A.O. Smith 750 & 1000 Application guide

1
A.O. SMITH WATER PRODUCTS CO., INC.
5621 W. 115TH STREET • ALSIP, ILLINOIS 60803
Phone: [phone] • Fax: [phone]
Website: www.hotwater.com
PRINTED IN U.S.A. 0403 211691-000
NATURALGAS
TRAIN/BLOWER
ASSEMBLY
See pages 5-7
PROPANEGASTRAINASSEMBLY
See pages 8-10
WATERWAYS&
COMBUSTION
CHAMBER
See page 2
EXHAUST &DRAIN
ASSEMBLY
See page 3
BY-PASS
See pages 8-10
WIRING/HARNESS&PROBES
See page 12
JACKET/FRAMEASSEMBLY
See page 4
CONTROLBOARD
See page 11
WATERINLET
See page 3
PSD-3-153
COMMERCIALPOWERBURNERBOILER
REPLACEMENT PARTS LIST
COPPERBOILERSFORHYDRONIC
HEATING & HOT WATER SUPPLY
LEGENDMODELSLB/LW:500,750&1000
SERIES:300-301

2
LB/LW WATERWAYS & COMBUSTION CHAMBER PARTS LIST
LW Models
LB Models
Item Description Model 500 Model 750 Model 1000
Note: Replacement housing assemblies (item 10) are currently all steel
type. When replacing the housing assembly both the inner gasket
(item 9) and outer gasket (item 7) must also be replaced. In addition,
high temperature silicone sealant (item 19) is required to fix the gaskets
to the surfaces.
The Tub Replacement Kit is available for replacing housing assemblies.
When ordering use p/n 211742 for LB/LW 500 models, p/n 211742-1 for
LB/LW 750 models and p/n 211742-2 for LB/LW 1000 models.
1 ................ Bracket ........................................................................................ 191602........................191602.................... 191602
2 ................ Burner and Cone Assembly ....................................................... 191850...................... 191850-1................ 191850-2
3 ................ Combustion Chamber Assembly ............................................ 191529-2.................... 191529-3 ................ 192129-1
4 ................ Connector, Hose......................................................................... 191765........................191765.................... 191765
5 ................ Coupling, Flexible w/Gasket....................................................... 191780........................191780.................. 191780-1
6 ................ Cover, Outer ................................................................................ 210408........................210408.................... 210404
7 ................ Gasket, Outer ............................................................................ 211594-1.................... 211594-1 ................ 211594-1
8 ................ Gasket, Burner.......................................................................... 191564-1.................... 191564-1 ................ 191564-1
9 ................ Gasket, Inner............................................................................... 211594........................211594.................... 211594
10 ................ Housing Assembly ..................................................................... 211742...................... 211742-1 ................ 211742-2
11 ................ Ignitor .......................................................................................... 192334........................192334.................... 192334
12 ................ Insulation, Burner ....................................................................... 191618........................191618.................... 191618
13 ................ Nut, Manifold ............................................................................... 191555........................191555.................. 191555-1
14 ................ O-Ring ......................................................................................... 191556........................191556.................. 191556-2
15 ................ Probe, Outlet Temp./ECO ........................................................... 210572........................210572.................... 210572
16 ................ Probe, Inlet Temp. ...................................................................... 210571........................210571.................... 210571
17 ................ Screw, Machine #8-32, 3/8" Long, SST ..................................... 210444........................210444.................... 210444
18 ................ Screw, Machine #8-32, 1" Long SST ......................................... 191770........................191770.................... 191770
*19................ Sealer, Silicone Hi-Temp ......................................................... 191482-1.................... 191482-1 ................ 191482-1
20 ................ Sensor, Flame ............................................................................ 210421........................210421 .................... 210421
21 ................ Spacer Ring ................................................................................ 191554........................191554.................. 191554-1
22 ................ Switch, Safety Flow ..................................................................... 211480........................211480.................... 211480
23 ................ Tee Assembly ............................................................................. 191583........................191583.................... 192387
24 ................ Tube Assembly, Primary (LW Models) ...................................... 210900........................210900.................... 192388
24 ................ Tube Assembly, Primary (LB Models) ....................................... 210901........................210901.................... 192225
25 ................ Tube Assembly, Outlet ...............................................................210425........................210425.................... 210426
26 ................ Tube Assembly, Secondary ....................................................... 210912........................210912.................... 192386
27 ................ Washer, Flat #8 SST................................................................... 191768........................191768.................... 191768
28 ................ Restrictor-Air, Top Cover .......................................................... 191926-1.................... 191926-1................ 191926-1
*Item Not Illustrated.

3
LB/LW EXHAUST, DRAIN & WATER INLET ASSEMBLY PARTS LIST
Item Description Model 500 Model 750 Model 1000
1 ................ Clamp, Hose (Large)......................................................................... 191794-1..............191794-1 ............ 191794-1
2 ................ Clamp, Hose (Small)......................................................................... 191794-3..............191794-3 ............ 191794-3
3 ................ Nut, Hex .............................................................................................. 191817-1..............191817-1 ............ 191817-1
5 ................ Drain, Flange .......................................................................................191620................. 191620 ................ 191620
6 ................ Drain, Flange Assembly ...................................................................... 191625................. 191625 ................ 191625
7 ................ Elbow....................................................................................................191664................. 191664 ................ 191664
9 ................ Gasket, Drain .......................................................................................191622................. 191622 ................ 191622
10............... Gasket, Vent ......................................................................................... 191683................. 191683 .............. 191683-1
11............... Nipple ................................................................................................. 20373-15..............20373-15 ............ 20373-18
12............... Nut, Hex 1/4" (Serrated) .......................................................................210226................. 210226 ................ 210226
13............... O-Ring ................................................................................................ 191556-1..............191556-1 ............ 191556-1
14............... Plate, Drain Seal..................................................................................191626................. 191626 ................ 191626
15............... Pump Assembly, Circulator (LW Models)........................................... 211611................. 211612 ................ 211538
16............... Tube Assembly, Inlet (LW Models) ................................................... 210897-1..............210897-2 .............. 192308
17............... Tube Assembly, Primary (LB Models) ................................................210901................. 210901 ................ 192225
18............... Tube Assembly, Primary (LW Models)................................................210900................. 210900 ................ 192388
19............... Tubing, Condensate......................................................................... 191746-24........... 191746-24 .......... 191746-24
20............... Tubing, Pressure .............................................................................. 191562-26........... 191562-26 .......... 191562-26
21............... U-Bolt Assembly ..................................................................................191938................. 191938 ................ 191938
22............... Valve Drain ............................................................................................26273................... 26273 .................. 26273
23............... Vent Assembly .....................................................................................210499................. 210499 ................ 210494
24............... Vent Flange ........................................................................................ 191685-4..............191685-4 ............ 191685-5
25............... Washer, Plain..................................................................................... 76820-18..............76820-18 ............ 76820-18
26............... Vent Support, Bracket (1000 Model Only) ............................................ - - - - - ....................- - - - -.................. 192194
27............... Vent, Restricting Ring (500 Model Only) ........................................... 191923-2.................- - - - -................... - - - - -
28............... Vent, Restricting Ring (Series 301 LP)................................................ - - - - - ....................- - - - -................ 191923-1

4
LB/LW JACKET/FRAME ASSEMBLY
Item Description Model 500 Model 750 Model 1000
1 .......... Bolt, Machine 5/16" - 18 ..............................................................191358-1 ................... 191358-1................... 191358-2
2 .......... Control Panel Assembly .............................................................210601-1 ................... 210601-1..................... 210601
3 .......... Display Board ............................................................................... 210219 ....................... 210219 ...................... 210219
4 .......... Frame Assembly .......................................................................... 210495 ..................... 210495-1................... 210501-1
5 .......... Gasket, Dispaly ............................................................................ 210130 ....................... 210130 ...................... 210130
6 .......... Grommet ....................................................................................... 97591 ......................... 97591......................... 97591
7 .......... Handle .......................................................................................... 191802 ....................... 191802 ...................... 191802
8 .......... Junction Box Assembly ...............................................................190438-1 ................... 190438-1................... 190438-1
9 .......... Junction Box Cover ........................................................................ 2233 ........................... 2233........................... 2233
10 ......... Label, Control Panel .................................................................... 210561 ....................... 210561 .................... 210561-1
11 ......... Locknut, Star................................................................................... 1953 ........................... 1953........................... 1953
12 ......... Locknut #6 -32.............................................................................. 210207 ....................... 210207 ...................... 210207
13 ......... Nipple, Chase ............................................................................... 41994 ......................... 41994......................... 41994
14 ......... Nut, Lock Hex 5/16" - 18 (1000 Model Only) .................................- - - - -.......................... - - - - - ......................... 97896
15 ......... Panel Assembly, Left Side..........................................................191796-1 ................... 191796-1................... 191796-3
16 ......... Panel Assembly, Right Side ........................................................ 191796 ....................... 191796 .................... 191796-2
17 ......... Panel, Lower Front ....................................................................... 191805 ....................... 191805 .................... 191805-1
18 ......... Panel, Rear (Natural) ................................................................... 191748 ..................... 191748-1..................... 192191
........... Panel Rear (Propane).................................................................. 191748 ..................... 191748-4..................... 210020
19 ......... Panel, Top Cover.......................................................................... 191609 ....................... 191609 .................... 191609-1
20 ......... Plate, Rear Cover (1000 Model Only) ............................................- - - - -.......................... - - - - - ........................210214
21 ......... Screw, Hex Head 5/16" ................................................................ 210125 ....................... 210125 ...................... 210125
22 ......... Screw, Hex Head #6-32 ............................................................... 210206 ....................... 210206 ...................... 210206
23 ......... Switch, Blower Prover .................................................................. 191666 ....................... 191666 ...................... 191666
24 ......... Switch, Blocked Flue.................................................................... 191667 ....................... 191667 ...................... 191667
25 ......... Switch, Rocker.............................................................................. 191665 ..................... 191665-1................... 191665-1
26 ......... Support Bracket (Propane Only)....................................................- - - - -......................... 210019 ...................... 210017
27 ......... Transformer (75VA)...................................................................... 192528 ....................... 192528 ....................... - - - - -
........... Transformer (100VA) .....................................................................- - - - -.......................... - - - - - ........................210449
28 ......... U-Bolt Assembly (Water way) ...................................................... 191938 ....................... 191938 ...................... 191938
29 ......... Washer, Flat ................................................................................. 191359 ....................... 191359 ...................... 191359
30 ......... Washer, Lock ............................................................................... 191480 ....................... 191480 ...................... 191480
31 ......... Switch, Relay ..................................................................................- - - - -......................... 211546 ...................... 211546
32 ......... Blower Speed Control.................................................................. 191922 ........................ - - - - - ......................... - - - - -
33 ......... Control Bracket Assembly ........................................................... 210902 ..................... 210902-3................... 192167-2

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LB/LW NATURAL GAS TRAIN/BLOWER ASSEMBLY- MODEL 500
Item Description Model 500 Item Description Model 500
20 ....Nut, Hex 1/4" ..................................................... 170272
21 ....Orifice,Air.......................................................... 192737
22 ....Orifice, Union (See Orifice Table Below)
23 ....Plug, 1/8" Pipe .................................................... 3348
24 ....Port, Observation Lower................................... 191572
25 ....Port, Observation Upper................................. 191572-1
26 ....Screen, Air Inlet................................................. 192041
27 ....Screw, Cap 1/4" .............................................. 190960-2
28 ....Srew, Flathead #8-32 x 1/2" ............................. 191542
29 ....Screw, Flathead #8-32 x 3/4" ......................... 191542-1
30 ....Switch, Low Pressure .................................... 191149-1
31 ....Tee, 1/8" ............................................................. 40119
*32 ....Tee, Union ........................................................ 191633
*33 ....Tubing, Pressure .............................................. 191562
*34 ....U-Bolt Assembly ............................................. 191938-1
35 ....Valve, Main Gas ................................................ 191956
36 ....Washer, Lock 1/4" .............................................. 1006
37 ....Shutter, Blower ................................................. 211694
38 ....Flange, Shutter ................................................. 211695
39 ....Manual Firing Valve .......................................... 3423-4
*Item Not Illustrated. DETAILBACKVIEW
Note: Manual firing valve (item 43) used on
US models made on or after 6/1/02.
1 ....Blower ............................................................ 211613
2 ....Blower Adapter Assembly ............................. 191645
3 ....Blower Manifold Assembly ............................ 191832
*4 ....Bracket, Blower .............................................. 191773
*5 ....Clamp, Hose ................................................. 191794
6 ....Elbow, 1" .............................................................1630
7 ....Elbow, Union 1" .............................................. 2482-1
8 ....Elbow, Street 1".............................................. 190763
9 ....Flange, Observation Port............................... 191573
10 ....Gasket, Blower .............................................. 191623
11 ....Gasket, Burner............................................... 191564
12 ....Gasket, Manifold ............................................ 191565
13 ....Gasket, Port (1/8" Thick) ................................ 191576
14 ....Manifold Assembly ........................................ 191610
15 ....Nipple, Close 1/8" ......................................191147-1
16 ....Nipple, Close Stainless ................................ 191772
17 ....Nipple, Tapped ...........................................86397-11
18 ....Nipple, 1" x 9 1/2"............................................. 86397
19 ....Nipple, 1" x 2" ......................................................1177
19A ....Nipple, Pipe 1"x2 1/2" .........................................1179
19B ....Nipple, Pipe 1"x14 1/2" ................................. 86397-6
Model NaturalGas Size(In.) Elevation(Ft.)
LB & LW-500 191884-0 0.391 0 - 2000
LB & LW-500 191884-1 0.384 2001 - 3000
LB & LW-500 191884-2 0.374 3001 - 4000
LEGENDORIFICETABLE

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LB/LW NATURAL GAS TRAIN/BLOWER ASSEMBLY- MODEL 750
Item Description Model 750
1 ..... Blower ............................................................. 211614
2 ..... Blower Adapter Assembly .............................. 191645
3 ..... Blower Manifold Assembly ............................. 191832
*4 ..... Bracket, Blower ............................................... 191773
*5 ..... Clamp, Hose................................................... 191794
6 ..... Elbow, 1" ........................................................... 1630
7 ..... Face Bushing 1"x1 1/4" ................................... 99376
*9 ..... Flange, Observation Port ................................ 191573
10 ..... Gasket, Blower................................................ 191623
*11 ..... Gasket, Burner ................................................ 191564
12 ..... Gasket, Manifold ............................................. 191565
*13 ..... Gasket, Port (1/8" Thick) ............................... 191576-1
*14 ..... Gasket, Port (1/16" Thick) ............................... 191576
15 ..... Manifold Assembly ......................................... 191610
16 ..... Nipple, Close 1/8"......................................... 191147-1
17 ..... Nipple, Close Stainless ................................. 191772
18 ..... Nipple, 1x4 1/2" with Tap .............................. 86397-14
19 ..... Nipple, 1" x 9 1/2" ............................................. 86397
20 ..... Nipple, 1" x 2" .................................................... 1177
20A ... Nipple, 1"x15 1/2" ......................................... 86397-13
20B... Nipple, 1 1/4" x 2" .......................................... 86505-29
20C .. Nipple, 1"xClose ............................................... 1342
20D .. Nipple, 1"x4" ................................................... 86397-7
Item Description Model 750
21 ....Nut, Hex 1/4" ..................................................... 170272
22 ....Orifice,Air........................................................ 192737-1
23 ....Orifice, Union (See Orifice Table Below)
24 ....Plug, 1/8" Pipe .................................................... 3348
*25 ....Port, Observation Lower................................... 191572
*26 ....Port, Observation Upper................................. 191572-1
27 ....Screen, Air Inlet................................................. 192041
*28 ....Screw, Cap 1/4" .............................................. 190960-2
*29 ....Srew, Flathead #8-32 x 1/2" ............................. 191542
*30 ....Screw, Flathead #8-32 x 3/4" ......................... 191542-1
31 ....Switch, Low Pressure .................................... 191149-1
33 ....Tee, 1/8" ............................................................. 40119
*34 ....Tee, Union ........................................................ 191633
*35 ....Tubing, Pressure .............................................. 191562
*36 ....Tubing, Top Cover Assembly ........................... 191925
*37 ....U-Bolt Assembly ............................................. 191938-1
38 ....Valve, Main Gas ............................................... 78481-3
*39 ....Washer, Lock 1/4" .............................................. 1006
40 ....Valve, Solenoid Gas ......................................... 192189
41 ....Shutter, Blower ................................................. 211694
42 ....Flange, Shutter ................................................. 211695
43 ....Manual Firing Valve .......................................... 3423-4
DETAILBACKVIEW
*Item Not Illustrated.
Note: Manual firing valve (item 43) used on
US models made on or after 6/1/02.
LEGENDORIFICETABLE
forboilers builtonor after6/01/02.
Model NaturalGas Size(In.) Elevation(Ft.)
LB & LW-750 191884-11 0.464 0 - 2000
LB & LW-750 191884-12 0.450 2001 - 3000
LB & LW-750 191884-13 0.443 3001 - 4000 Model NaturalGas Size(In.) Elevation(Ft.)
LB & LW-750 191884-3 0.484 0 - 2000
LB & LW-750 191884-5 0.469 2001 - 3000
LB & LW-750 191884-7 0.461 3001 - 4000
LEGENDORIFICETABLE

7
LB/LW NATURAL GAS TRAIN/BLOWER ASSEMBLY - MODEL 1000
DETAILBACKVIEW
Item Description Model 1000
1 .....Blower ...............................................................192195
2 .....Blower Adapter Assembly .............................. 192215-1
3 .....Blower Manifold Assembly ............................... 192217
4 .....Bracket, Blower ................................................. 210214
5 .....Clamp, Hose .................................................. 191794-3
6 .....Elbow, 1-1/4" ..................................................... 192216
7 .....Elbow, Union 1-1/4"......................................... 86506-1
8 .....Flanged Observation Port ................................ 191573
9 .....Gasket, Blower Air Inlet .................................... 192213
10 ....Gasket, Burner.................................................. 191564
11 ....Gasket, Manifold ............................................... 191565
12 ....Gasket, Port (1/8" Thick) ................................... 191576
13 ....Nut, Hex 1/4", Serrated ..................................... 210226
14 ....Manifold Assembly - Air/Gas ............................ 192309
15 ....Nipple, Close 1/8" .......................................... 191147-3
16 ....Nipple, Close Stainless ................................. 191772-1
17 ....Nipple, Tapped ................................................ 86505-3
18 ....Nipple, 1-1/4" x 38-1/2" ................................... 86505-28
19 ....Nipple, 1-1/4" x 28-3/4" ................................... 86505-27
20 ....Nipple, 1-1/4" x 2" .............................................. 86505
21 ....Nipple, 1-1/4" x 3" ............................................ 86505-2
22 ....Nipple, 1-1/4" x 4" ............................................ 86505-6
23 ....Nut, Hex 1/4" ................................................... 191817-1
Item Description Model 1000
24 ....Orifice, Air (Series 300 - Nat. Gas)................. 192737-3
24 ....Orifice, Air (Series 30211 - L.P. Gas) ............ 192737-2
25 ....Orifice, Union (See Orifice Table Below)
26 ....Plug, 1/8" Pipe .................................................... 3348
27 ....Port, Observation Lower................................... 191572
28 ....Port, Observation Upper................................. 191572-1
29 ....Screen, Air Inlet............................................... 192220-1
30 ....Screw, Cap 1/4" .............................................. 190960-2
31 ....Srew, Flathead #8-32 x 1/2" ............................. 191542
32 ....Screw, Flathead #8-32 x 3/4" ......................... 191542-1
33 ....Switch, Low Pressure .................................... 191149-1
34 ....Shutter, Blower ................................................. 192593
35 ....Shutter Flange .................................................. 192592
36 ....Tee, 1/8" ............................................................. 40119
37 ....Tee, Pressure ................................................... 191633
38 ....Tubing, Pressure .............................................. 191562
40 ....U-Bolt Assembly (Gas Train) ......................... 191938-3
41 ....Valve, Main Gas ............................................... 78481-3
42 ....Valve, Firing....................................................... 3423-3
43 ....Valve, Solenoid Gas ......................................... 192189
44 ....Washer, Plain ................................................. 76820-18
42 ....Manual, Shut-off Valve ...................................... 211695
*Item Not Illustrated.
LEGEND ORIFICE TABLE
Natural Size Elevation
Gas (inches) (Feet)
192222 0.555 0-2000
192222-1 0.537 2001-3000
192222-2 0.533 3001-4000

8
Item Description Model 500
1 .....Valve, Main Gas .............................................. 191956-1
2 .....Regulator, LP ..................................................... - - - - -
3 .....Valve,Manual Shut-Off ..................................... 3423-4
4 .....Pipe Plug ............................................................ 3348
5 .....Switch, Low Gas Pressure............................. 191149-3
6 .....Nipple, 1" ........................................................... 86397
7 .....Nipple, 1" ......................................................... 85397-6
8 .....Nipple, 1" ............................................................ 1177
9 .....Elbow, Union, 1" ...................................................... 2482-1
LB/LW PROPANE GAS TRAIN ASSEMBLY - MODEL 500
Item Description Model 500
10 ....Elbow, 90° Street, 1" ............................................... 190763
11 ....Elbow, 90°, 1"..........................................................1630
12 ....Nipple, 1" ................................................................1179
13 ....Nipple, 1" ............................................................86397-11
14 ....Nipple, 1/8" .........................................................191147-1
15 ....Tee, 1/8" .................................................................40119
16 ....Nipple, Close Stainless .......................................191772
17 ....Orifice, Union .............................. See Orifice Table Below
Item Description Model 500
1 .....Ball Valve ..............................................................191935
2 .....Hex Reducing Bushing LW Models
.....(for use w/Relief Valve)........................................ 91940-1
3 .....Relief valve:
..... LB Model ............................................................210451
..... LW Model .......................................................... 98883-3
4 .....Tee, 2" x 2" x 1" ....................................................78685-2
5 .....Tee, 2" ...................................................................191584
6 .....Tee, 2" x 2" x 2" ....................................................78685-4
7 .....Valve, Drain ............................................................26273
*8 .....Valve, Manual Shutoff ............................................ - - - - -
*9 .....Orifice, Gas Assembly (See Orifice Table)
*10 .....Tube, Condensate ............................................191746-120
*11 .....Strap, Cable .........................................................99592-2
LB/LW BY-PASS PARTS LIST - MODEL 500
Please update these numbers
On LB models the circulating pump must be between
the boiler inlet and the bypass (see figure below).
LW models have pump mounted inside the jacket.
*ItemNotIllustrated.
Propane Gas Size (In.) Elevation(Ft.)
192741 0.229 0 - 2000
192741-1 0.226 2001 - 3000
192741-2 0.223 3001 - 4000
LB/LW500 ORIFICE TABLE

9
Item Description Model 750
1 .......Valve, Main Gas .............................................77780
2 .......Regulator, LP ................................................192460
3 .......Valve,Manual Shut-Off ................................. 3423-3
4 .......Pipe Plug ........................................................3348
5 .......Switch, Low Gas Pressure.........................191149-3
6 .......Nipple, 1-1/4" ...............................................86505-8
7 .......Nipple, 1-1/4 ................................................86505-2
8 .......Nipple, 1-1/4" ..............................................86505-10
9 .......Elbow, Union ,1-1/4" ......................................... 86506
10.......Elbow,
90° Street , 1-1/4" ..................................94516
11.......Elbow, 90°, 1-1/4" .........................................192216
LB/LW PROPANE GAS TRAIN ASSEMBLY - MODEL 750
Item Description Model 750
12.......Nipple, 1-1/4" ...............................................86505-3
13.......Nipple, 1-1/4" ..............................................86397-11
14.......Nipple, 1-1/4" ...............................................86505-4
15.......Tee, 1/8" ........................................................192465
16.......Connector, Angle 1/8".....................................1578
17.......Bleeder, Tube ...............................................210016
18.......Bleeder, Tube ...............................................192461
19.......Bushing, 1" x 1-1/4" .......................................99376
20.......Nipple, Close Stainless ...............................191772
21.......Orifice, Union .............................. See Orifice Table Below
Item Description Model 750
1 .....Ball Valve ..............................................................191935
2 .....Hex Reducing Bushing LW Models
.....(for use w/Relief Valve)........................................ 91940-1
3 .....Relief valve:
..... LB Model ..........................................................210451-1
..... LW Model .......................................................... 98883-3
4 .....Tee, 2" x 2" x 1" .................................................... 78685-2
5 .....Tee, 2" ...................................................................191584
6 .....Tee, 2" x 2" x 2" .................................................... 78685-4
7 .....Valve, Drain ............................................................26273
*8 .....Valve, Manual Shutoff ........................................... 3423-3
*9 .....Orifice, Gas Assembly (See Orifice Table)
*10 .....Tube, Condensate............................................191746-120
*11 .....Strap, Cable ......................................................... 99592-2
LB/LW BY-PASS PARTS LIST - MODEL 750
Please update these numbers
On LB models the circulating pump must be between
the boiler inlet and the bypass (see figure below).
LW models have pump mounted inside the jacket.
*ItemNotIllustrated.
Propane Gas Size (In.) Elevation(Ft.)
192741-3 0.286 0 - 2000
192741-5 0.282 2001 - 3000
192741-7 0.278 3001 - 4000
LB/LW750 ORIFICE TABLE

10
Please update these numbers
LB/LW PROPANE GAS TRAIN ASSEMBLY - MODEL 1000
Item Description Part No.
1......Valve, Main Gas, LP 300 Series .................. 77780
2......Regulator, LP 301 Series ...........................192460
3......Valve, Firing ................................................. 3423-3
4......Pipe Plug....................................................... 3348
5......Switch, Low Gas Pressure ....................... 191149-3
6......Nipple, 1-1/4” ............................................ 86505-13
7......Nipple, 1-1/4” ............................................. 86505-2
8......Nipple, 1-1/4” ........................................... 86505-17
9......Elbow, Union 1-1/4” ..................................... 86506
Item Description Part No.
10......Elbow, 90 Street 1-1/4”................................. 94516
11......Elbow, 90 1-1/4” ......................................... 192216
12......Nipple, 1-1/4” w/Tapping.......................... 86505-32
13......Nipple, 1-1/4” ............................................. 86505-6
14......Nipple, 1-1/4” ............................................ 86505-4
15......Tee, 1/8” NPT Branch.................................. 192465
16......Connector, Angle 1/8” ................................... 1578
17......Bleeder, Tube..............................................210016
18......Bleeder, Tube..............................................192461
19......Nipple, Close Stainless ........................... 191772-1
20......Orifice, Union ....................... See Orifice Table Below
1 ........Ball Valve ........................................................................191935
*2 ........Tank/Pump Kit (LW Models) ..........................................210625
3 ........Hex Reducing Bushing (LB Model) .............................. 91940-8
4 ........Flush Bushing (LB Model) ........................................... 192163-2
5 ........Relief Valve (LW Model) ................................................ 98883-3
........Relief Valve (LB Model) ................................................ 210451-2
6 ........Strap, Cable (not shown).............................................. 99592-2
7 ........Tee, Condensate ......................................................... 192040-1
8 ........Tee (For use w/relief valve):
...............LW Model ............................................................... 78685-4
...............LB Model ................................................................. 191584
9 ........Tee2"x2"x2"....................................................................191584
10 ........Tee2"x2"x3/4"................................................................ 78685-4
11 ........Valve, Drain ..................................................................... 26273
12 ........Valve, Manual Shutoff ..................................................... 3423-3
13 ........Vent Patch Assembly .....................................................192161
14 ........Nipple (For use w/relief valve)
...............LW Model .............................................................. 20373-12
...............LB Model ................................................................ 92706-4
15 ........Clamp, Hose................................................................ 191794-1
LB/LW BY-PASS PARTS LIST - MODEL 1000
Item Description Part No.
On LB models the circulating pump must be between
the boiler inlet and the bypass (see figure below).
LW models have pump mounted inside the jacket.
*Item Not Illustrated.
Propane Gas Size (In.) Elevation(Ft.)
192739 0.333 0 - 2000
192739-1 0.329 2001 - 3000
192739-2 0.325 3001 - 4000
LB/LW1000 ORIFICE TABLE

11
LB/LW WIRING CHART
LB/LW CONTROL BOARD WHC 1502
Part Number 210128
WHC1502
COLOR GAUGE PARTNUMBER***
White 14 41974
Black 14 99650
Green 14 41972
White 16 86580
Black 16 86578
Green 16 69058
White 18 170595
Black 18 170596
Green 18 170606
Blue 18 191719
Red 18 170603
Yellow 18 170604
Brown 18 170890
White/Red 18 191700
White/Yellow 18 191702
White/Black 18 191699
Black/White 18 191694
Yellow/Blue 18 191708
Red/Green 18 191717
*** Use dash number to indicate length of wire.
Example: 20 inch long red wire would be expressed as 170603-20.

12
Outlet Temperature
Control/ ECO Assembly
210572
Tank Probe
Harness Assembly
210604
Pressure Flow Switch
Harness Assembly
210576
Transformer
Harness Assembly
210578 (Model 1000)
211330 (Models 500 & 750)
Ignition
Harness Assembly
210575
Gas Valve HarnessAssembly
210574-1 (Propane)
210574-2 (Nat. & Prop. Model 500)
A.O. SMITH WATER PRODUCTS CO., INC.
5621 W. 115TH STREET • ALSIP, ILLINOIS 60803
Phone: [phone] • Fax: [phone]
Website: www.hotwater.com
Inlet Temperature
Control Assembly
210571
Tank Probe (LW Models)
211541-1
22-16 Ga. 16-14 Ga. 22-18 Ga. #10 Stud 22-18 Ga.
LB/LW WIRING AND HARNESS ASSEMBLY
78468 99593-6 78469 191673 42573 210091 210152 99599-2
Power HarnessAssembly
210579-1
(-0 0n -500 Models Only)
PSD, Alsip, IL
Blower
Harness Assembly
210609 (Model 1000)