Question about Rinnai Webstone The isolator EXP tankless water heater Service Valves WRIK

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Rinnai tankless water heater code 12

My gas water heater won't fire up and flashes code 12 on the screen. I need a list of trouble codes to find out what this means.

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  • Anonymous Mar 26, 2014

    fault code 11 on rinnai tankless water heater ,tries to fire but it kicks out. has done this in the past but then started working on its own.what is the most common problem with this fault code?

  • Anonymous Mar 27, 2014

    Loud humming sound from rinnai thankless heater


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12 - Flame Failure or Poor Ground

1. Immediate code 12 is usually a defective gas valve, power supply problem, or defective fan motor wiring harness.

2. If code 12 occurs after a few seconds it indicates that proper operation was established, but then stopped unexpectedly.

3. Verify that fuel is being supplied to the unit.

4. Check for proper electrical ground. Unit must use a grounded power supply.

5. Check for flue blockage on inlet or exhaust.

Posted on Dec 31, 2008

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I have a rinnai tankless water heater
the gas valve has been replaced
the problem only occurs in the summer in the heat of the day
the heater shuts off and a code 12 appears
when the unit is turned off and then back on all is fine for a while
the unit sets inside the garage and is vented out the brick [horizonally] about 2'

Posted on Jul 30, 2009

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Check your vent pipe to make sure air inlet side is clear and interior Metal piping is connected together thru out to prevent air discharge and air intake from cross contamination , this causes unit to function during slow flow rate ( lav ) but show 12 code during higher flow rate usage (tub ).

Posted on Jul 27, 2013

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Check any other appliances that run on gas during that period...might have a problem with a regulator outside. Sometimes if they are exposed to direct sunlight, the metal inside can expand and stick. Usually they will hum occasionally when warm under heavy load

Posted on Sep 14, 2009

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2 Answers

My Rinnai tankless water heater flashes 11 when calling for hot water.

Your Owner's manual should help. No manual, try MFG website, or email their customer service. Or try

Apr 27, 2015 | Rinnai Water Heaters

1 Answer

Our rinnai R94LS will shut off after running several minuets and shows error code#10. I'll turn it off for several minutes and turn back on, run system for several minuets and it will shut off again and...

Tankless computer is not working.
Error 10 is blocked flue or inadequate air supply. Or failed PC motherboard, or failed sensor etc.
Get more fresh air to unit. Check if bird built nest on flue pipe. If flue exits side of house, look for obstructions nearby that can slow the exit of poisonous vent byproduct into the air you breathe. For example trash cans and boxes or parked car etc.

Call service technician who is qualified to work on tankless computer. This will be a well-seasoned veteran of computer technology and plumbing expertise ... a plumber who knows how to fix computers lol.
This person will catch unit up on required yearly maintenance, and check specialized operation conditions needed for tankless computers to function properly.
If tankless computer is older than 5 years, then compare it to your 5-year old laptop, and assume same level of glitches and problems.

Solve any tankless problem yourself, today, for $385 by installing tank type heater from local box store:


Aug 29, 2013 | Rinnai Water Heaters

1 Answer

Wont always fire up

You probably have tankless water heater.
What brand water heater?
Gas or electric?
Is this new installation or old installation?

For Rheem tankless:
Copy following link: If you get no error code on remote control, then scroll down to 'no error code.'

Oct 11, 2012 | Water Heaters

1 Answer

Rheem RTG-64DVN model, brand new unit installed during the weekend. fired up but shout down automatically within about 5 seconds. showed error code 12.

contact your gas company if the error code is "12," indicating that the gas supply was interrupted.

have a good day !! In LP models, the 12 error code may also appear if the LP gas supply has gotten low. To clear the code, replace or refill the LP gas supply.

go here for a list of codes for rheem tankless water heaters--

May 09, 2011 | Rheem Tankless Hot Water Heater...

1 Answer

Our tankless water heater is not turning on, but

blockage at pilot ,gas valve faulty ,if you have a changeover valve fault could be there

Oct 07, 2009 | Rinnai Webstone The isolator EXP tankless...

1 Answer

Rinnai Tankless won't stay on

how far is the tankless from the gas meter? error code 12 means it doesn't have enough gas running to it. is the 3/4 flex true 3/4 or is it 1/2 with 3/4 threads. have you checked your BTU load on your house to make sure your 1'' pipe can handle everything else you have on the house? sounds like to me you dont have the right amount of gas to the unit.

Sep 29, 2009 | Rinnai Webstone The isolator EXP tankless...

1 Answer

Rinnai tankless water heater

LC is the error code that you get when you have limescale buildup in the heat exchanger. You need to flush your heat exchanger. If you have the manual for your water heater, use it. The manual to mine is attached. The procedure for flushing it is covered on page 12. I suggest that you have a certified Rinnai plumber perform this task as it requires a ciruclating pump and some hoses that you need to connect to your water heater. If you don't perform this task, it is possible that you will need to replace your heat exchanger and this is not something covered by Rinnai's warranty.

Sep 21, 2009 | Rinnai Webstone The isolator EXP tankless...

1 Answer

This things beeping and flashing 12 everytime we

check the error codes on it by pressing the on off button for 2 seconds then while holding the on/off button press the up button this should display the last 9 error codes let me know what they are

Jul 28, 2009 | Rinnai Water Heaters

1 Answer

Code 12 flashes after third faucet is turned on

The gas pipe size that heater has to 3/4 pipe size.If you got anything any smaller than that is won't give enough gas.Check the gas psi at the heater.If it's bottle gas you should 11 psi.and natural gasline you need 5psi.

Mar 09, 2009 | Rinnai Webstone The isolator EXP tankless...

1 Answer

What does a "12" on my 96-140 F Degree Control mean?

I'm mr.grzz, thanks for your question,
A code 12 on your control pad has allot of different remedy's, here is a list,
First it means you have flame failure,
Check to make sure the gas is turned on at the unit, the meter, or tank,
Check for obstructions at the flue outlet,
did they check the gas pressure ?
was the gas line properly sized ?
did they use Rinnai venting materials and was it properly installed ?
was the condensate collar installed properly ?
did they double check to make sure vent lengths were well within limits?
did they verify the dip switch settings ?
is the unit properly grounded ?
check power supply for loose connections
check power supply for proper voltage and voltage drop
check to see if flame rod is connected, this would be my guess as to what your trouble is, flame rod could be out of alignment as well, not sensing the flame, the other thing would be the gas, air in the line will cause this too,
the flame rod needs checked for carbon build up,
I know thats alot of tech data, but for all intents and purposes it would be best if you called a service tech that is certified with Rinnai to come take care of you, if you call them tell them you have a code 12, and you have the possible causes, I hope this was of help to you, please write us back and let us know, again thanks for your question, mr.grzz

Jan 21, 2009 | Rinnai Digital Remote Water Heater Control...

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