Navien CH-180 Operation Manual page 9

Combination water heater operation
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Equipment Protection and Personal Safety
9. Freeze Protection
During the heating season, a sensor inside the combination water heater will
automatically detect and initiate a safety heating cycle to prevent internal equipment
damage from occurring freezing temperature exist.
Note! － When there is no gas supply available, the circulation pump will automatically start
up to guard the pipes from freezing.
10. Gas Pressure Control
To prevent damage from over pressure, each combination water heater is protected
from occasional surges in gas pressure by a pressure regulator located in the gas
valve.
11. Short-Circuit Protection
Any short-circuit occurring in the combination water heater‟s electrical circuit will
immediately „blow‟ the internal glass fuse(s) and automatically cut off the gas supply.
12. Lightning Protection
Each combination water heater is specially grounded internally and externally to protect
against lightning strikes.
13. Carbon Monoxide Protection
The combination water heater is designed to maintain a safe air and gas ratio and
combustion rate. This function is continuously monitored by the combination water
heater‟s air-ratio control module.
14. Thermostat Control Failure
Should the thermostat fail to function properly, as a safeguard, the combination water
heater‟s gas supply will be automatically shut down.
15. Auto Fan Detection
The rotation of the fan is automatically detected and controlled. Fan failure will stop
the operation of the combination water heater.
16. Boiling Prevention
Excessive temperatures will automatically stop the combination water heater.
17. Space Heating Freeze Protection
Use only inhibited propylene glycol solutions specifically formulated for space
heating systems. Do not use ethylene glycol, which is toxic and can attack gaskets
and seals used in space heating systems.
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