Do Navien boilers have a built-in frost protection?

Navien boilers incorporate a built-in frost thermostat which automatically turns on the boiler and pump if the water in the boiler falls below 10°C, providing the electrical supply is on. The boiler will operate until the water temperature in the system reaches approximately 10°C measured on the flow sensor in the boiler.

Any other pipework outside of the boiler should be protected from the risk of freezing and protected with suitable insulation. Additional protection from external frost thermostats and pipe thermostats should also be considered.

For systems requiring freeze protection, use only inhibited propylene glycol, specially formulated for hydronic heating systems; use of other types of antifreeze may be harmful to the system and will void the warranty.