Water heater short cycling - too hot??

[BPSOswego]

New (recently installed) Bradford White 40 gal natural gas water heater, Model #MI403S6FBN, S/N JA16045342 w/Honeywell gas control valve. This is a natural draft, not power vent.

Issue: Call for heat as indicated by proper flash code (double strobe then 3 second pause) on gas control valve. Burner ignites, burns for approximately two to three minutes, then shuts down for about 1 minute, then ignites again. Cycle continues indefinitely, and the call for heat flash code remains constant the entire time. Water from tap is extremely hot... almost too hot... yet call for heat continues.

Additional (possibly related??) issue: rust can be seen on exterior of tank when access panel is removed... looks like water has (or is) running down outside of tank. (pics attached)

My first thought was that this is not a new tank.... but serial number seems to confirm that it is (or at least was when it was installed).

I know short cycling can be caused by a faulty flame sensor (thermocouple), but in my experience that would cause the burner to shut down after only a few seconds, not three minutes (or in the case of thermocouple, the pilot light would not remain lit). So I ruled that out.

At this point I am leaning towards a faulty gas control valve, or... if there is such a thing... a faulty temperature sensor which reports the water temp to the gas control valve.

Thank you in advance for any help....

Mike

 

[johnjh2o]

My first guess is the tank is leaking. It could also be rain water gettng into the flue pipe.

 

[journeyman]

It looks like your heater is 2yrs old by serial number. Did you check top of heater for leaks. Do you have soft water? It is still under warranty. I would install a new one that heater looks bad. Is heater located in a basement or cellar?

 

[BPSOswego]

No leaks at top of heater. We do not have soft water (city water). It's located in first floor laundry room. Not sure about warranty... I'm told by the property owner that I work for that the original installer will no longer come back and service it because they are 'too busy'. (They have made several unsuccessful attempts to repair since installing it, but I don't know exactly what they have done.) the biggest red flag to me is that the thing won't stop calling for heat even though the water is hot.... That's why I was leaning towards control valve or some component of the control valve)


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[journeyman]

Any plumber can do a wareanty swap out. It has a six year warranty on tank and parts to heater. It does not have to be plumber that installed it . Any reputable company can do work. Bradford white will buy you a new heater but plumber will charge you labor. If heater looks like that after two years take advantage of the warranty. Can you take a picture of entire heater and top of heater