Noritz 111 making loud noise when water is on

Remove the bird's nest in the flue.

The 10, 59, 90 and 99 error codes indicate that a Noritz heater has experienced a combustion abnormality. In most cases, it is the result of an obstruction in the heater's flue. Examine the flue to see if it is blocked by debris and clean if necessary.

How To Resolve The Seven Most Common Noritz Tankless ...

Noritz https://www.noritz.com > Blog
Nov 16, 2015 - This error code involves a breakdown in communication between two tankless water heaters using the Quick Connect Cord. It can occur when more ...

Troubleshooting Noritz Tankless Water Heaters and Error Codes

home-water-heater.com https://www.home-water-heater.com > noritz-error-co...
Error code 90 and 99 ... Action: Check for the obstructed venting, improper gas burning (flame shape and color change). Ensure the water heater gets the ...

Error Codes for a Noritz Water Heater - Waterheatertimer.org

..

For a Noritz tankless water heater, error number 78 indicates a problem with the fan motor. The instructions below will help you clear the problem number 78 on a Noritz tankless water heater:

1. Turn off the power to the tankless water heater by either disconnecting it or switching off the circuit breaker.
2. Verify that the fan motor is clear of any obstructions or debris that may be preventing it from operating properly.
3. Check the fan motor is receiving power by measuring the voltage across the fan leads with a voltmeter. Verify that the electrical connections to the fan motor are secure if there is no voltage.
4. If the fan motor is broken or not operating properly, it may need to be replaced. For further assistance with the repair or replacement of the fan motor, you can contact Noritz technical support or a certified HVAC specialist.
5. After resolving the issue with the fan motor, switch off the power to the tankless water heater for at least 30 seconds before turning it back on. This will clear the error code and restore normal operation to the device.
6. If you are unclear or uncomfortable with any of these processes, you should seek the aid of a certified HVAC specialist or Noritz technical support.

You should try to describe the noise and what is happening when the noise occurs. Then someone may be able to give you some diagnosis of the problem. For example, does it make a big boom sound went it lights the burners? Then you might need to clean and adjust the pilot light.

MAke sure your flu is not making any 90degree turns. Use 45degree turns only. Error 99 is a combustion error. Usually referring to a blocked/obstructed flu. That said, a flu wit a lot of 90degree turns can act like restrictions to tankless heaters. If the flu i straight and clear, then you have a burner problem. Somethign you want Noritz to deal with.

Do you have a well our on city water? Check in coming water pressure make sure it is not over 60psi

Loud rumbling noises are often caused by either water boiling in the burner or by entrapped air in the system. To help prevent water boiling make sure that the boiler system has a pressure between 15 - 30 psi. Also check for sufficient water flow and remove any sediment from the in-line filter. To remove entrapped air, install an automatic or manual air vent at the highest point in the heating system and also make sure you have a properly working micro-air vent installed. With the unit turned off and cooled down, you can also try flipping the lever on the pressure relief valve to try and flush out any air in the heat exchanger . Hope this helps.

If the heater is more then a few years old the heat exchanger is probably corroded. Air flow from the blower motor can't squeeze thru the exchanger fins and causes loud vibrations. It can sometimes be cleaned but usually requires replacement of the heat exchanger. If you are not familiar you should definitely have a professional sevice the unit. Continued use in its current state can cause many other issues. Be prepared because the heat exchanger is the most expensive part of the heater and the most difficult to replace

This sounds like "water hammer"
You can fix this by adding an arrester to the water line. here is a link to what they look like and how they work http://www.plumbingsupply.com/waterhammerarresters.html

You may want to check you water pressure and see if its over 80 psi.
If so then your regulator needs to be adjusted or replaced. If you home does not have a regulator and the city has upped the pressure then you will need to install one. water hammer will break pipes over time and can damage that nice water heater you have.

Things to Check:

1. incoming gas pressure (minimum 5" when unit firing)
2. Make sure damper on top of unit isn't sticking
3. check vent length and #elbows versus installation manual specs
4. if above 2000', disconnect high elevation termination

If these all check out, you'll probably need to do a manifold adjustment. Call Noritz for assitance on this.

I called Noritz error code 16 is a overheat problem. Noritz say's to flush your coil with vinegar or CLR.
Use a small pump to recirculate the CLR or vinegar through the system for 45 minutes and flush with fresh water. This worked for me.