Navien NCB-190/060H, User'S Information Manual

24 Troubleshooting

If resetting the boiler and attempting the remedies suggested below do not resolve the problem, contact an 

authorized technician, a licensed professional, or Technical Support at 1-800-519-8794 for service instructions.

Problem

Possible Cause(s)

What to do

No water comes 

out when the 

hot water tap is 

opened.

●

Is the domestic cold inlet filter 

clean?

●

Is an error code displayed on the 

front panel?

●

Is the boiler frozen?

●

Ensure that the shut–off valves on the hot 

and cold pipes are open.

●

If an error code is displayed, refer to  

“5.2 Understanding Error Codes” on 

page 25.

The water from the 

hot water faucet is 

cold or turns cold 

and stays cold.

●

Is the hot water faucet open wide 

enough draw at least 0.5 gallons of 

water per minute (GPM) through 

the boiler?

●

Is an error code displayed on the 

front panel?

If an error code is displayed, refer to  

“5.2 Understanding Error Codes” on page 25.

The water from the 

hot water faucet is 

not hot enough.

Is the set temperature too low?

●

Check the boiler’s temperature setting. Refer 

to See “3.2 Adjusting the Temperature” on 

page 10.

●

Check for cross piping between the heating 

supply and heating return lines. 

The water from the 

hot water faucet is 

too hot.

Is the set temperature set too high?

Check the boiler’s temperature setting. See “3.2 

Adjusting the Temperature” on page 10.

Space heating side 

malfunction

Is the setting temperature too low?

Check the boiler’s temperature setting. See “3.2 

Adjusting the Temperature” on page 10.

Is there power to the system, or is the 

system in stand by?

Make sure the power is on, and plugged into 

the outlet with the correct voltage. Press the  

Power button ( ) and raise the setting 

temperature. Make sure the boiler is turned on.

Is the system running for domestic hot 

water (DHW)?

When the unit is heating for DHW, the heating 

side does not work.

Is the filter on the heating side 

restricted?

Clean out filters that belong to the heating 

side.

5.    Troubleshooting

5.1    Solving Basic Problems

If you experience a problem with the boiler, refer 

to the following chart for possible remedies. Error 

codes that appear on the front panel display are 

explained in the following section.

For minor problems, resetting the boiler may resolve 

the issue. To reset the boiler, press the Back button  

(

) on the front panel.