Top View: Bth 120 - 250 Models; Top View: Bth 300 - 500 Models - A.O. Smith BTH 120 Service Handbook

TOP VIEW: BTH 120 - 250 MODELS

Ignition Control
CCB Assembly
Water Outlet
1 - 1/2" NPT

TOP VIEW: BTH 300 - 500 MODELS

Ignition Control
Powered Anode
(Short)
CCB
Assembly
Water Outlet
1 - 1/2" NPT
Powered Anode
(Short, BTH 150-250
Models Only)
Junction Box
Assembly
Servicing should only be performed by a Qualified Service Technician
Junction Box
Assembly
Burner/ Blower
Assembly
Upper Temperature Probe
UIM
VFD
UIM
Upper Temperature
Probe
Powered Anode
(Long)
Blower Prover
Switch
(Label Color: Green)
Blocked Air
Intake Switch
(Label Color: Blue)
Blocked Exhaust
Switch
(Label Color: Red)
Exhaust/
Condensate Elbow
Burner/ Blower
Assembly
Blower Prover Switch
(Label Color: Green)
Blocked Air
Intake Switch
(Label Color: Blue)
Blocked Exhaust
Switch
(Label Color: Red)
Powered Anode
(Long)
Exhaust/
Condensate Elbow
5