At the beginning of the pre-purge period on...

At the beginning of the pre-purge period on...

Question 1 of 270705eccefa3bacbc34ba4d47c59

At the beginning of the pre-purge period on an automatic auxiliary boiler equipped with a programmed control system, the unit will not restart if airflow is not sensed and __________.

Question 1 of 27070

Q

At the beginning of the pre-purge period on an automatic auxiliary boiler equipped with a programmed control system, the unit will not restart if airflow is not sensed and __________.

🔍 Key Concepts

• Pre-purge period purpose on an automatic auxiliary boiler (what are you trying to clear and make safe before ignition?) • What the airflow proving device (airflow switch) is there to confirm before the control will allow a restart • Which condition related to damper position is safest before starting forced draft and fuel admission

💭 Think About

• Think about what could happen if fuel were admitted when the gas path was not properly set up — which damper position would be more dangerous at the start of pre-purge? • Ask yourself: is pre‑purge done with the gas path open or closed, and what does the control system want to be sure of about the damper before it proceeds? • Look at the options that mention pressure: are they part of air/furnace gas safety, or are they unrelated to the purpose of pre‑purge?

✅ Before You Answer

• Be clear on the main safety objective of pre‑purge (what are you removing from the furnace and uptakes?). • Identify which interlock must be satisfied together with airflow proving at the beginning of pre‑purge, before any fuel is admitted. • Eliminate any answer choices that deal with pressures not directly connected to combustion air and flue gas removal at startup.