Navien NR-20DU Manual page 62

Problem
The water from the hot
water faucet is cold or
turns cold and stays cold.
The water is not hot
enough.
The water is too hot.
Possible Cause(s)
Is the cold water inlet filter clean?
Is the hot water faucet open wide
enough draw at least 0.5 gallons of
water per minute (GPM) through
the water heater?
Is an error code displayed on the
front panel?
If there is an external recirculation
system installed, is there a check
valve on the recirculation return
line?
Is the set temperature too low?
Is the set temperature set too high?
What to do
Clean the cold water inlet filter. See
"4.4 Cleaning the Inlet Water Filter and
Recirculation Inlet Filter" in the Operation
manual.
Open the hot water faucet completely.
If an error code is displayed, refer to the
Error Code Guide.
Check the water heater's temperature
setting. Refer to "3.2 Adjusting the Water
Temperature" in the Operation manual.
Check for cross plumbing between the
cold and hot water lines.
Check the water heater's temperature
setting. See "3.2 Adjusting the Water
Temperature" in the Operation manual.