Bradford White SW-2-40R-L Installation And Operating Manual page 21

Water Connections continued-
Typical steam boiler without connections available below the
water line is not recommended due to insufficient water
temperature, especially during warmer months when the space
heating system is not operational. Boiler water temperature at
the bottom of a steam boiler can be 50°F lower than the boiler's
water temperature limit setting during such periods.
FILL BOILER SYSTEM
1. On new boiler installations, do not purge the boiler or space
heating system through the water heater. During any boiler or
space heating system flushing, cleaning, or purging, the water
heater should be isolated to avoid possible attack on the carbon
steel coil by chemical additives.
2. Purge air from boiler/water heater piping.
3. Check system for leaks. Repair as necessary.
NOTICE
21