Cleaning The Return Adapter Filter; Protecting The Boiler From Freezing - Navien NCB-20LHWE Installation & Operation Manual

6. Close o any heating zones that do not require draining and
open a purge valve to drain the space heating side. Open
all domestic hot water taps completely to drain the water
heating side. The water that remains in the plumbing lines
will drain out.
Pump Drain Plug
7. Open the pump drain plug.
8. Allow the residual water to drain from the boiler.
9. When the water is completely drained, reinsert the return
adapter lter and close the pump drain plug.
10. To re ll the boiler follow the steps of "Draining the Boiler" in
reverse.

12.3 Cleaning the Return Adapter Filter

To clean the lter:
1. Drain the boiler. Refer to "12.2 Draining the Boiler" on
page 56.
2. Remove the lter and rinse it with clean running water
(cold). If necessary, scrub it clean with a brush.
3. Reinsert and tighten the lter.
4. Fill the boiler and check for proper operation.

12.4 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 an 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 gas 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 o , as
long as the electric supply is still connected.
Do not close the gas 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 gas 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 57