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I have a problem on a NH-1501-DV boiler. We are having the…

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I have a problem...

I have a problem on a NH-1501-DV boiler. We are having the code 643 coming up all the time. Sometimes it will come up 3 or 4 times in a day and other times it go for 2 or 3 days/

Contractor's Assistant: I'll do all I can to help. How long have you been dealing with this?

We had it several years ago and we put in a new ignition plug and that seemed to help, I ordered a new ignition plug a week ago and installed it with a new gasket but it still is giving us problems.

Contractor's Assistant: Do you plan on doing the work yourself?

I do most of the work on the several pieces of Noritz equipment that I have because the people don't have as much knowledge about them as I do.

Contractor's Assistant: Anything else we should know to help you best?

One thing that I saw was that one of the caps on the vent pipe is off. This is in one of my several homes that I own. I have done electrical and plumbing work for most of my life.

Contractor's Assistant: How long has this been going on? And how severe is the problem?

This has been going on for over a month but the vent cap has been off for over a year. The family that lives in the home get up and press the on button whenever the registers are blowing cold air. They are surviving but it is very problematic.

Submitted: 4 months ago.Category: HVAC
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Answered in 1 hour by:
3/6/2018
HVAC Technician: Gaztech, HVAC Technician replied 4 months ago
Gaztech
Gaztech, HVAC Technician
Category: HVAC
Satisfied Customers: 921
Experience: Owner at Gaztech
Verified

Hi I amCustomer a independent technician, I will assist you with your issue.

Don't forget to rate the 5 star rating AT THE TOP OF PAGE if we are done. this will credit me for assisting you.

Code 643 is water flow switch failure.

Not necessarily a flow switch failure it could be water flow failure, lets make sure the Water flow pump is running.

There might just be a loose wire connection,

If you are at ease and have a multi meter, check amperage of pump to see if its running by opening the pumps electrical box and check the wire nuts for good connection.

  1. Check if there is power (120 Vac) and Amperage to the pump when the boiler turns on.
  2. If the pump is running, make sure that there is no air in the system preventing water flow, if you have all the air out of the system and the pump is running, then the problem is likely a bad flow switch.
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