🔍 Key Concepts

• Purpose of a recirculating (bypass) valve in a fuel oil return flow system • What happens to fuel temperature and pressure when burners are not yet taking full flow • Difference between service system piping and storage/settling/heating circuits

💭 Think About

• In a return flow system, when burners are shut or oil is not yet being burned, where must the excess oil safely go so the service pump does not deadhead? • Which destination would keep the oil within the same pressurized loop, maintaining temperature and pressure for quick burner light‑off? • Which options would be impractical or unsafe just before lighting off a cold boiler and why?

✅ Before You Answer

• Identify which option keeps oil within the same service loop instead of sending it back to storage or settling tanks • Consider which path avoids introducing cold, unheated oil right before light‑off • Eliminate any choice that would likely cause pump overloading, temperature loss, or unnecessary cycling through other treatment stages