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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 7747
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I am getting error code 643 on my Noritz tankless boiler,

Customer Question

I am getting error code 643 on my Noritz tankless boiler, mode NG 1501 DV NG
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.

Hello,

Tell me please if this looks like the manual for your water heater or not, and if the error code read outs happen to printed on the wiring diagram glued to the back side of the large service panel/ cover.

http://www.noritz.com/u/products_files/user_s_information_manual_nh150_dv_nh199_dv_eng_and_french.pdf

Please attach a well focused, close up photo of the wiring diagram glued inside the service panel, the picture needs to be taken from straight on, in very good light.

You can use the paper clip- icon at the right end of the tool bar at the top of this dialog box to attach it here.

If there is no paper clip-icon, look for the '+attach files'link at left of your send button.

I can mark it up with trouble shooting instructions.

You will need a multi meter ($30 at a hardware store) and some experience working with appliances, let me know a lot about your skill sets in those regards.

Expert:  Phil replied 1 year ago.

Hello,

Tell me please if this looks like the manual for your water heater or not, and if the error code read outs happen to printed on the wiring diagram glued to the back side of the large service panel/ cover.

http://www.noritz.com/u/products_files/user_s_information_manual_nh150_dv_nh199_dv_eng_and_french.pdf

Please attach a well focused, close up photo of the wiring diagram glued inside the service panel, the picture needs to be taken from straight on, in very good light.

You can use the paper clip- icon at the right end of the tool bar at the top of this dialog box to attach it here.

If there is no paper clip-icon, look for the '+attach files'link at left of your send button.

I can mark it up with trouble shooting instructions.

You will need a multi meter ($30 at a hardware store) and some experience working with appliances, let me know a lot about your skill sets in those regards.

6 Dec 2015, 6:38 PM

Customer: replied 1 year ago.
Hi Phil,
Yes this is the manual. I've attached a photo of the schematic. I have a volt meter and can troubleshoot, but am not sure where I would get parts if they need replacing.
What does error 643 designate?
Arv
Expert:  Phil replied 1 year ago.

Hello again, Code 643 is water flow switch failure...

Actually it is not so much as a flow switch failure as it is water flow failure, so we check the fuses first, and make sure the pump is running.

http://screencast.com/t/Eqeb8RK9eF

If the pump is running, we make sure that there is no air in the system preventing water flow, if we have all the air out of the system and the pump is running, then the problem is likely a bad flow switch.

Tell me if the water heater is being used for domestic hot water only, or if it is also being used to heat the home, and if that is the case, tell me if it is in the floor radiant heat, baseboards or radiators.. we can discuss how air bleed the system after that.

It may be however that just a fuse is blown and the pump is not running.

Let me know about all that, we can go from there.

Customer: replied 1 year ago.
Hi Phil,
There is power to the unit. I opened the pumps electrical box to check if there is power to the pump when the boiler turns on. I redid the wire nuts and it's now working.
Thank you
Customer: replied 1 year ago.
By the way, this is used only for baseboard heat
Expert:  Phil replied 1 year ago.

Good work!

Thanks for letting me work with you. Please locate the 'rate your expert button' and click one of the ratings .If you still need help let me know!. Rating will not increase your charges, nor close the question, but is how I earn my living. Thanks again.