Protecting The Boiler From Freezing - Navien LCB700-21RS Installation & Operation Manual

5. Close the water supply valve on the inlet to the boiler. If
there is no valve, turn off the water supply at the water main.
6. Close off any heating zones that do not require draining and
open a drain valve to drain the central heating side.
7. Open all domestic hot water taps completely to drain the
water heating side. The water that remains in the plumbing
lines will drain out.
8. Open the pump drain valve.
9. Allow the residual water to drain from the boiler.
10. When the water is completely drained out, close the drain
valve.
To refill the boiler, follow the steps above in reverse.
Note
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12.3 Protecting the Boiler from Freezing

CAUTION
Damage due to freezing is not covered by the Navien limited
warranty.
If the boiler is connected to a circuit that could freeze, the circuit
pipes must be suitably insulated. All pipes installed outdoors
must be insulated according to applicable legislation. The boiler
electronic control includes a freeze protection function that
prevents the boiler from freezing in very cold weather. It remains
on standby and takes priority over all other boiler functions
while the boiler is connected to the electrical mains and oil
supply, i.e. it remains enabled even when the boiler is in standby
position.
To ensure that the boiler does not freeze, follow these
guidelines:
Do not unplug the power supply cord, except for routine
maintenance. The boiler has a freeze protection function that
requires electricity. The freeze protection function will operate
regardless of whether or not the power is turned on or off, as
long as the electric supply is still connected.
Do not close the oil valve, except for routine maintenance, as
this will limit additional freeze protection.
If the boiler will not be used for an extended period, drain
the boiler. If the power or oil supplies must be disconnected
for an extended period, drain the boiler. Freezing damage
may occur if there is water remained in the boiler in cold
weather.
Maintaining the Boiler 69