Navien NHB-055, Руководство по обслуживанию

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124 NHB Service Manual Version 1.0
5.3.2 Water Temperature Issue
Error type Cause Check method
Boiler is not operating
properly.
Front panel power off Hot water does not run if the front panel is switched off.
Defective heating supply
thermistor
The temperature is sensed higher than the actual temperature due to a defective
hot water (cold water) sensor.
●
Hot water temperature is low although hot water is recognized by the boiler.
●
The cold water temperature sensor may not work be working properly.
Low hot water
temperature
Hot water setting error Check the hot water temperature setting on the front panel.
Water mixed with cold
water.
The temperature of hot water at the tap is low while the temperature is high at the
hot water outlet.
●
Cold water and hot water are mixed due to improper pipe installation.
●
Cold water and hot water are mixed due to improper piping at the hot water
faucet.
No hot water from the
valve
Check the pipe
1. The cold water valve is closed.
2. Check if the cold water filter (external) is clogged with foreign substance.
3. Check if the cold water / hot water pipes are frozen during the winter.
4. The main heat exchanger is clogged (by scale).
5. Low inlet water pressure
Cold water flows
temporally
Pre-heating does not
work
The system initiates the external circulation preheating when a recirculation mode
is selected on the front panel DIP switches. Confirm the DIP switch settings.