47
Figure 22 - Typical Burner Cabinet
1.
Ignitor
– Powered by Flame Safety Control to initiate light-off.
2.
Rollout Switch 1 (SW-05)
– Normally closed temperature activated switch. Mounted on bracket at the
firing tube. Senses flame roll-out in the event of a blocked tube, low airflow, or low gas pressure. If
flame-rollout is present, the switch de-energizes heater circuit on the furnace. Must be manually reset
by pressing the small button on top of the switch.
3.
Furnace High Temperature Switch (SW-04)
– Normally closed switch. De-energizes the heater
circuit on the furnace if temperature exceeds mechanical set-point. Automatic recycling.
4.
Flame Rod (FR-01)
– Continuously senses for the presence of flame in heating mode after ignition
has commenced. This sensor is wired to the Flame Safety Control (FSC-1).
5.
Rollout Switch 2 (SW-13)
– Normally closed temperature activated switch. Mounted on bracket at the
firing tube. Senses flame roll-out in the event of a blocked tube, low airflow, or low gas pressure. If
flame-rollout is present, the switch de-energizes heater circuit on the furnace. Must be manually reset
by pressing the small button on top of the switch.
6. Single Burner Assembly – Capacity varies by unit size.
7. Split Furnace Assembly – Capacity varies by unit size. When the high turndown option is selected, a
split furnace will be present.
A. First Stage – Smallest of the two stages. The first stage can modulate for the highest turndown.
B. Second Stage – When first stage is 100% operational, the second stage can modulate to meet the
required heating capacity.
1
2
5
3
4
Split Burner
4
5
1
3
2
1
Single Burner
4
7B
6
7A
