Flame error after opening and closing 2nd source cold

[peterski]

Rinnai tankless.

Drawing hot on one or multiple sources everything is fine.
Draw hot at source one...heater works fine but if cold is called from a 2nd source (sink, toilet, etc) heater works fine until the 2nd source cold is closed. Once cold is closed at the 2nd source, the heater throws a no flame error and stops heating. Turning water from first source off for a few seconds then restarting and everything is fine.

Thoughts?

 

[Twowaxhack]

So if you’re taking a shower and the toilet gets flushed it throws a 12 code ?

And you can make that repeat every time ?

But you can run the same shower plus other hot fixtures at the same time without issue ?

Is it possible you have old water piping ? Low cold water pressure ?

 

[peterski]

Correct...and it is only when the 2nd source cold is turned off that the no flame error is thrown and it stops heating. while the cold is running it is fine. and yes, 2nd source hot, no issues.

Not sure what you mean by old water piping? Pressure isn't great in the house as we have a well but this wasn't an issue when the heater was new. It happened after a year or two of having it.

 

[Twowaxhack]

I can’t explain why you’re getting a code 12 from the info you’ve given.

Maybe someone else can.

I’d start trouble shooting the unit with a manometer to check gas pressures.

I’d check the flame rod or rods. To do that you need to replace the gasket most of the time that seals it to the unit
Check cold water inlet filter.

Check for any loose wiring connections and make sure the electrical circuit is grounded.

Make sure the vent is clear

Basically I would be just generally checking the unit over hoping to find something.

Clean the unit with vinegar if it’s due.


After doing all that I would call tech support. With electrical test meter and digital manometer in hand standing in front of the unit.

 

[wpns]

Does it shut down immediately when you turn off that cold water, or does it shut down after a little while (maybe after the pump cycles?) Does that heater have a pressure sensor on it? If so it sounds like your water pressure is fluctuating enough that it causes something to trip out. I would look at things like the precharge in the well pressure tank, the check valve, the pump function, and ensure that the switch high and low limits are what they should be.

 

[Twowaxhack]

Max water pressure is 150
Minimum is 20

Recommended water pressure for full flow is 50 psi.

If this helps.

 

[peterski]

thank you...that is very very helpful. most appreciated.

Does it shut down immediately when you turn off that cold water, or does it shut down after a little while (maybe after the pump cycles?) Does that heater have a pressure sensor on it? If so it sounds like your water pressure is fluctuating enough that it causes something to trip out. I would look at things like the precharge in the well pressure tank, the check valve, the pump function, and ensure that the switch high and low limits are what they should be.

yes, pretty much shuts down immediately. I do think it has a pressure sensor on it. Going to take a look at it this weekend.

 

[peterski]

Max water pressure is 150
Minimum is 20

Recommended water pressure for full flow is 50 psi.

If this helps.

thank you!