Richmond Tankless Water Heater Code 12 [Why+ How To Fix]

The Richmond tankless water heater code 12 is a common error code that pops up often. It represents flame failure of the heater. The most common reason behind it is issues related to the gas supply. However, it can also be caused due to the following reasons:

  • LP Is Running Low.
  • Dirty Flame Rods.
  • Clogged Venting.
  • Power Supply Issues.
richmond tankless water heater code 12

We’ll discuss all of these issues that can lead to the error code 12 in your Richmond on demand heater and learn how you can fix each of them in this guide. Without further ado, let’s dive right in!

Richmond Tankless Water Heater Code 12 [Fully Solved]

We’ll talk about all the major reasons behind the error code 12 on your Richmond encore tankless water heaters and their fixes in this section.

richmond tankless water heater

Note: You can also read our Richmond tankless water heater troubleshooting guide.

The number one reason behind the error code 12 on your tankless water heater is issues related to the gas supply. If the gas supply to your heater is interrupted in any way, this error code can pop up.

There are a lot of things that can go wrong and cause issues with the gas supply. Let’s take a look at the most common ones:

i). Gas Shut Off Valve Not Being Fully Open

The gas shut-off valve located under your water heater always needs to be fully opened to ensure the proper supply of gas. If it’s not completely open, the gas supply will be interrupted and that will cause either error code 11 or 12.

gas shut off valve not being fully open

Inspect the gas shut-off valve and see whether it’s on or not. It should be completely parallel to the gas pipes when it’s turned on. If it’s perpendicular to the gas lines, it means it’s off.

Leaving the gas shut-off valve off is a common mistake most people make when they do some sort of maintenance work on their heater. They simply forget to turn the gas shut-off valve back on after completing the job.

ii). Blockage In Gas Lines

The gas lines need to be clean and free of any blockages for the proper flow of gas. If dirt or debris gets into the gas lines or there’s a leak somewhere that allows air to come in and gas to escape, it’ll lead to mayhem. In such instances, it’s normal for the error code 12 to pop up.

blockage in gas lines

Start by checking the gas lines for obstruction first as they’ll be easier to detect. If you’re unable to find any, the next thing is to check them for leaks. There are different tests you can do to find it. If you don’t feel comfortable doing it yourself, you can always take the help of a professional.

iii). Low Gas Pressure

The next thing that you should check when you’re on the lookout for different gas supply related issues is the gas pressure. Your owner’s manual will contain information about the right gas pressure for your tankless unit.

low gas pressure

Generally, Richmond tankless water heaters have an acceptable range of 4″ w.c to 10.5″ if you’re running it on natural gas. If you’re using LP as fuel, the gas pressure should be between 8″ w.c to 13″ w.c.

When it comes to the manifold gas pressure, it should be 2.52″ w.c + fan pressure for natural gas and 7.36″ w.c + fan pressure for LP. If both the gas inlet and manifold pressure aren’t at the right level, your heater won’t ignite.

You can check the gas pressure yourself if you have a manometer. If you don’t have access to that tool, you should contact your local gas supplier company to send someone to check it out for you.

iv). Small Gas Lines

Another potential reason behind getting the error code 12 from your tankless water heater is using undersized gas lines. There are guidelines in your owner’s manual regarding the material and size of the gas lines. You must follow them to ensure that your heater burns properly without any issues.

When you use a smaller gas supply line than recommended, it fails to support the BTU Load of the water heater. The improper combustion leads to flame failure and causes error code 12. Not only that, it can make the burners form soot and increase the level of condensation in the heater.

v). Faulty Gas Control Valve

The gas control valve is an important component inside your water heater that regulates the flow of gas to ensure proper combustion. When the valve goes bad due to any reason whatsoever, the combustion gets interrupted and it often results in the error code 12 popping up.

The gas valve wires getting damaged can also cause this issue. When the gas valve fails, you won’t be getting any flame from the burners. As the gas valve can’t be repaired, the only option you have is to replace it. You’ll learn how to do it in the solution section of this guide.


As you’ve read this far, you should realize that several gas related problems can lead to the error code 11. The right solution depends on the problem you’re dealing with.

Luckily, the most common problem which is the gas shut-off valve not being fully open can be easily fixed. Make sure you turn the valve all the way until it’s fully parallel to the gas lines. If it wasn’t fully on before, doing it should get rid of the error code.

Next, if you find a blockage in the gas lines, you need to clear them. You can use thin wires or compressed air to get the dirt out of the gas lines. If air is leaking into the lines, you need to bleed them and replace the area of the leak.

When you’re dealing with low gas pressure, it has to be fixed by contacting your gas supplier. Have an expert gas technician adjust the gas pressure as per the specifications mentioned in the owner’s manual.

The next thing you need to do is to make sure that the gas lines you’re using are of the correct sizes. Usually, the gas lines used in Richmond heaters are ½ and ¾ inches.

Refer to your owner’s manual to get the right information for your specific model. Bad regulators can also cause issues with the gas pressure in your water heater. So, replace the regulator if it has gone bad.

The final thing to check in issues related to gas supply is the gas control valve. Follow these steps if the one you have has gone bad and you need to replace it:

  • Switch off the power supply to the heater by flipping the circuit breaker or turning off the power outlet. Turn the gas shut-off valve perpendicular to the pipes to turn it off.
  • Remove the front panel of the heater and unplug the power cord from the heater. Shut off both the cold and hot water lines.
  • Locate the gas valve inside the heater and disconnect it from the wires by loosening the nuts.
  • Remove the two screws on the bracket that connect the gas valve to the cabinet and disconnect the gas valve.
  • Put the new gas valve in place of the old one and replace the damaged O-rings as well. Secure the valve in place by tightening the screws and connecting it to the wiring.
  • Reassemble the heater. Turn on the gas lines and the water lines and you’re good to go.

If the error code goes away after you have taken the above steps, you’re done here. But if none of these issues were causing the problem in your case, you have to keep on diagnosing to get to the root of the issue.

2. LP Is Running Low

This problem is specific to the ones who are using LP gas to fuel their heater. When you’re running low on LP gas, there won’t be enough fuel to ignite the heater.

LP is running low

Hence, the heater can go into flame failure mode and display the error code 12.


It’s incredibly easy to fix this problem. All you have to do is to replace the LP gas tank with a filled one or refill the existing tank with LP. When you do that, things should go back to normal. Check that the gas is being supplied at the right pressure to be sure that there are no gas related issues in your heater.

3. Dirty Flame Rods

The flame rods are important components in your heater as they detect the flame once the burner has ignited. These rods are L-shaped, about 3 – 5 inches long, and are connected to the control board.

dirty flame rods

When the flame rods operate properly, it signals to the control board that it detects a flame. Using this signal, the control board allows the heater to continue the inflow the gas to keep up the combustion in the heater.

Unfortunately, the flame rods can get dirty with time as there will be carbon deposits on them. When they’re covered by carbon, they won’t be able to detect the flame from the burner.

So, the control board will think that the heater isn’t able to start a flame and it’ll stop gas from flowing into the heater. Thus, the error code 12 will come up in your on demand Richmond tankless heater.


If the flame rods in your heater are dirty, you need to clean them. Here’s the step-by-step guide on how you can inspect flame rods, pull them out, clean them, and reinstall them:

Step 01 – Turn Off The Power Supply

  • As usual, we’ll start by flipping the circuit breaker to turn off the power supply to the water heater.
  • Close the shut-off gas valve.
  • Open the front panel of the heater and unplug the power cord.
  • Turn off the cold water line and the hot water outlet line.

Step 02 – Inspect The Flame Rods

  • Remove the printed circuit board of your heater to expose the flame rods.
  • Once you have eyes on the flame rods, inspect the condition of each of them.
  • If they’re dirty, remove them by disconnecting the plastic insert on one end and by removing the screws that secure it to the burner assembly on the other end.
  • Pull out the flame rods from the heater carefully.

Step 03 – Clean & Reinstall The Flame Rods

  • Rub the flame rods in the areas covered with carbon deposits with 100-grit sandpaper or steel wool to get the dirt out.
  • Use rubbing alcohol or acetone if you’re dealing with carbon deposits that are grimier.
  • Use paper towels to remove any specks of dirt.
  • Wait for the flame rods to dry before you put them back in the heater.
  • Once they’re dry, put the flame rods and reverse-engineer the above steps to get your heater back to normal.

That’s how you can easily replace the flame rods on your heater. If the flame rods are dirty, cleaning them will do the trick. But if they’re damaged, you’ll have to replace them altogether.

4. Clogged Venting

Combustion gases getting recirculated into the water heater to get burned again is one of the main reasons for getting the error code 12 on your Richmond tankless water heater.

richmond tankless water heater clogged venting

The combustion gas fails to escape through the exhaust vent if there’s a lot of blockage in them. The chances of rodents, cobwebs, specks of dirt, and insects being in the vents are much higher if it’s been a while since you have last cleaned them.

Exhaust vents with blockages can not only trigger an error code but also release carbon monoxide in your house. So, you shouldn’t take this issue lightly and immediately inspect your exhaust vent.

Another potential reason behind this issue if your exhaust vent isn’t blocked is a dirty air intake filter. If the air intake filter is not clean, it will limit the amount of air entering the combustion chamber and also cause an error code.


If you find that there’s a blockage in the exhaust vents of your heater, you need to clean them. You can use a vacuum cleaner to suck the dirt out of the exhaust vent. Replace the venting if needed and there’s a crack somewhere.

Next, check the air inlet filter. If it has become dirty, remove it from the water heater first. Then, clean it using a toothbrush and make sure you get all the dirt out. Once it’s dry, reinstall it. Clean it at regular intervals to prevent this problem from occurring again.

5. Power Supply Issues

The Richmond tankless water heater is powered by electricity. Any issues with the power supply can lead to the flame failure mode and make the error code 11 come up.

power supply issues

The two most common issues related to the power supply are the tripping of the circuit breakers and the power supply of the heater not being properly ungrounded.

The breakers get tripped when the voltage in the house reaches an unsafe level. When the heater’s power supply isn’t grounded, it can also shock you.

Apart from that, changes in the voltage level of the house and the wiring harness of the heater or the control board becoming loose or damaged can also cause issues with the heater.


Start by inspecting the circuit breakers first. If they were tripped, just put them back into their original positions. If there are earthing issues with your heater, you need to consult an electrician to fix it for you.

As voltage fluctuations can cause issues with your heater, keep your heater turned off for the time being when this problem is happening in your house. Once the voltage goes back to normal, turn it back on and start using it. If the wiring harness is damaged, you need to get it replaced.


What does WC in gas pressure mean?

Gas pressure is usually measured in WC or PSI. WC refers to a water column and it represents the amount of force required to push a column of water by a certain number of inches.

How often should you service your Richmond tankless water heater?

If you want to get the most out of your Richmond tankless water heater, you should service it as often as possible. We recommend performing maintenance on it at least once a year to prolong its lifespan.

How do you adjust the temperature on Richmond tankless heater?

To adjust the temperature on Richmond tankless heater, use the temperature adjustment buttons that are located on the remote control of your heater. Pressing the up button will increase the temperature and the down button will decrease the temperature.

How should you maintain your Richmond tankless water heaters?

The basic maintenance tasks for your tankless heater include flushing the heater, cleaning both the water lines, cleaning the water filters, removing any debris from the vents, and cleaning the flame rods.


The Richmond tankless water heater code 12 indicates flame failure. If you have completed this guide, you should know by now how to get rid of this error code in Richmond heaters.

Take your time to diagnose the issue that’s causing the error code as it can happen due to a wide range of reasons. Once you find the culprit, you can easily take corrective actions and fix the problem. Comment below if you have any other questions regarding Richmond tankless water heaters.

About David

David is a man who loves doing research and finding out the best solution to any type of heating appliance issues like heaters and fireplaces. Whenever he finds the perfect solutions to any issues of heating appliances after doing in-depth research, he loves to share them with his readers. In fact, his aim is to help his readers to fix the issues with their heating appliances easily.More about us .

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