A.O. Smith 100 Series Service Handbook page 73

BOILER TEMPERATURE LOG†
DATE/TIME OUTLET TEMP INLET TEMP‡ TEMP RISE ΔT READINGS TAKEN BY
† [Outlet - Inlet = Delta T D] Outlet (supply water) temperature minus inlet (return water) temperature equals the
temperature rise (Delta ΔT) through the boiler. Readings should be taken weekly. When the ΔT increases by 5°F
schedule deliming maintenance to ensure optimal efficiency and prevent heavy lime accumulation i the boiler's heat
exchanger.
‡ Sustained inlet water temperatures below 120°F can cause heavy condensation and the formation of copper oxide
on the copper heat exchanger tubes. This can restrict the flow of flue gases through the heat exchanger and cause
combustion problems. Ensure a bypass line and valve are installed and properly set to raise the minimum inlet water
temperature. Call the toll free technical support phone number on the back cover of this manual for further assistance.
Servicing should only be performed by a Qualified Service Agent 71