Appendix A - Sequence Of Operation; Two Stage Controller Logic - Bosch BGH96 Troubleshooting Manual

2 2 | Bosch 96% AFUE Gas Furnace

Appendix A - Sequence of Operation

Two Stage Controller Logic

A1. There are two heating modes:
A1.1 Low Fire Heating Mode: Only W1 signal
A1.2 High Fire Heating Mode: Both W1 and W2 signal
I f you are using a single stage thermostat, only a W1 signal will
be sent. In this scenario, the furnace will upstage from low to
high fi re via a timing sequence. The time delay is set via the S1-1
& S1-2 dip switches on the control board.
A2. If the furnace fails to ignite, there is a separate logic for the re-ignition
sequence.
Data subject to change
Troubleshooting Guide
01.2019 | BTC 770502101 A