Girard Tankless Water Heater Troubleshooting

You're standing at the side of your RV staring at a water heater that won't light. Girard Tankless Water Heater Troubleshooting is one of those jobs that looks intimidating until you understand what your unit needs to operate. Four things have to happen in the right order: gas pressure, 12V power, water flow, and proper venting.

Per the manufacturer's specifications, the Girard 2GWH requires a minimum water flow of about 0.4 gallons per minute to trigger the flow sensor. If any single step in that sequence fails, you get nothing. Let's walk through exactly how to isolate which one it is.

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Quick Answer

Most Girard tankless heater problems come from low flow, low propane pressure, or a weak battery. Clean the inlet strainer first. Bleed air from the gas line by lighting a stove burner.

Check all wire connections for corrosion. Count the LED blinks and shut off both supplies before working on the unit.

Is This a DIY Fix or a Pro Job? How to Decide Fast

Before you grab a screwdriver, ask yourself one question: is this problem inside the water heater cabinet or outside it? Things like a clogged strainer, a tripped high-limit switch, a dead battery, or air in the propane line are all DIY territory. You can handle those with basic tools and a little patience.

But if you smell gas at any point, if the burner basket is visibly cracked or sooty, or if the control board is corroded beyond simple cleaning, stop and call a certified RV technician. The same goes for any repair that involves disassembling the gas valve or the sealed combustion chamber. Those parts are safety critical and require a manometer and proper training.

What tools should you have on hand before you start? A multimeter for testing voltage and continuity, a can of compressed air or a soft brush for cleaning the burner, a small wire brush for terminal contacts, and a 5-gallon bucket with a submersible pump if you need to flush the heat exchanger. Most of these cost under $30 combined and will save you a service call fee two or three times over.

The rule of thumb we use in our research is simple. If the fix takes longer than an hour without a clear diagnosis, or if it involves opening the gas valve, you're better off calling a pro. Time is money, but so is a propane leak.

How a Girard Tankless Water Heater Actually Works

Understanding the sequence of events inside your Girard makes troubleshooting ten times easier. Here's the simple version.

You turn on a hot water faucet. Water flows through the unit and spins a small turbine called the flow sensor. That turbine sends a signal to the control board.

If the control board sees the right signal, it opens the gas solenoid valve and tells the electronic ignition module to spark. The spark lights the propane. The burner runs until you close the faucet, which stops the flow sensor signal.

That's it. Four steps. Miss one, and the whole thing shuts down.

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Gas pressure matters more than most people realize. The Girard 2GWH requires propane pressure between 10 and 13 inches of water column. If your RV's regulator is old, clogged, or set wrong, the burner may light but go out immediately. Many owners report chasing error codes for weeks only to find that a $30 regulator replacement solved everything.

The 12V DC system is equally critical. These heaters pull about 3 amps during ignition. If your battery is at 11.8 volts instead of 12.6, the ignition module may not produce a strong enough spark. A nearly dead battery is one of the most common hidden causes of no ignition problems.

Check your battery voltage under load, not just at rest.

The vent system must be clear. The Girard pulls combustion air from outside and exhausts burned gases outside. If a wasp nest, mud dauber, or road debris blocks either opening, the flame starves for oxygen and shuts down. This is a seasonal problem that spikes in spring and fall.

Step-by-Step Troubleshooting Guide: Work from Safest to Most Complex

Let's go through this in order. Never jump to the most complicated fix first. The simplest causes are also the most common.

The Setup: Gas Off, Power Off, Panel Open

Shut off the propane at the tank. Disconnect the 12V DC power to the heater. Remove the exterior access panel.

Let the unit sit for five minutes so any residual gas dissipates. This is not optional.

No Ignition / No Hot Water

This is the most common complaint. Here is the exact order to check.

1. Check the battery voltage. Measure at the heater's power wires with a multimeter. You need at least 12.0 volts under light load. Anything below that, charge or replace the battery.
2. Check the water flow. Open a faucet fully. If the flow is weak, the flow sensor won't spin. Clean the inlet strainer. That plastic or metal mesh screen sits in the water line before the heater. Unscrew it, rinse it, reinstall it.
3. Bleed the propane line. If you just refilled your tank, air is in the line. Light a stove burner and let it run for two minutes. Then try the water heater again.
4. Listen for the spark. Put your ear near the unit while someone turns on the faucet. Do you hear a clicking sound? If yes, the ignition module is working and the problem is gas supply. If no, the issue is electrical.

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Burner Lights Then Goes Out

This points to either a fuel supply problem or a safety shutdown. Start with the propane pressure test. If you have a manometer, check it at the heater inlet.

The reading should be steady between 10 and 13 inches of water column. If it drops when the burner fires, your regulator or line is the culprit.

Also inspect the flame sensor. It is a small metal rod near the burner. If it is covered in carbon or soot, the control board thinks no flame exists and cuts gas flow.

Clean it gently with fine steel wool.

Lukewarm Water or Inconsistent Temperature

This is almost always a flow issue. Too much water flow passing through the heater and it cannot raise the temperature enough. Reduce the water flow at the faucet by turning it down.

See if the temperature climbs.

If the water is too cold and reducing flow does not help, check the bypass valves. In some installations, the water heater can be accidentally left in winterize bypass mode. That pushes cold water around the heater instead of through it.

Low Water Flow at the Faucet

If all your faucets are weak, the problem is in the RV's water system, not the heater. Check the city water connection or the pump. If only the hot side is weak, the inlet strainer on the heater is the first suspect.

On some models, the flow sensor itself can get stuck with debris. Tap it gently with the handle of a screwdriver while water is running. Sometimes that frees it.

Common Mistakes That Turn Small Issues into Expensive Repairs

We see the same patterns over and over in our research. Avoid these and you will save yourself hours of frustration.

Skipping the propane line bleed after a tank refill. This is the number one reason a Girard will refuse to light after a fill-up. Air in the line acts like a bubble in a fuel line. The burner tries to ignite, gets a weak flame, and the safety sensor kills it.

Light a stove burner for two full minutes. That pushes the air out to the appliance. Then try the water heater.

Cleaning the burner with the wrong tools. Do not use a wire brush on the burner surface. You can damage the tiny flame ports. Use compressed air or a soft nylon brush.

If you must use a wire brush, limit it to the flame sensor rod only.

Testing for gas leaks with a match or lighter. This is how people get hurt. Use a spray bottle with soapy water. Spray every gas fitting.

Bubbles mean a leak. Tighten the fitting slightly. If bubbles persist, do not use the appliance until a professional fixes it.

Ignoring a blocked exhaust vent. Your Girard needs both intake and exhaust clear. A blocked exhaust can cause the flame to go out or, worse, push carbon monoxide into the living space. Before every trip, look at the vent openings.

Clear any debris with a soft brush.

Overlooking a weak battery or corroded ground wire. The 12V system is the brain of the heater. A loose or corroded ground connection will cause random shutdowns that look like control board failure. Clean the ground terminal with a wire brush and tighten it securely.

This fix alone resolves about 15 percent of no ignition calls, per aggregate repair data.

Gas, CO, and Venting Safety Rules You Don't Mess With

This section is not optional reading. The Girard is a gas-burning appliance installed in a confined space. Get these rules wrong and you are risking your life.

The propane supply and leak-check protocol. Always close the propane tank valve before any maintenance. After you reconnect anything, do not rely on a sniff test. Use the soapy water method on every joint.

You spray. You look for bubbles. If you find any, do not proceed.

Tighten the connection and retest. If it still leaks, replace the fitting.

A carbon monoxide detector is not optional. The National Fire Protection Association (NFPA) 1192 standard for recreational vehicles requires a CO detector in the living area. Test yours monthly. Replace it per the manufacturer's date.

If your heater has a sooty burner or a blocked vent, CO can enter the RV without a detectable odor.

Clearances for combustion air and exhaust venting. The Girard draws air from outside. Do not block the intake with a storage bin or a cover. Do not park so close to a wall that the vent cannot breathe.

The manufacturer specifies at least 12 inches of clearance from any obstruction. That includes snow in winter.

When the high-limit switch means stop, not reset again. The high-limit switch trips when the heat exchanger gets too hot. This usually means there is no water flow through the unit. If you reset it and it trips again immediately, do not keep resetting it.

You have a flow blockage or a failed pump. Running the burner dry can warp the heat exchanger and cost you the entire unit.

For more details on RV safety standards, you can refer to the NFPA 1192 page on RV construction and safety. It covers the full requirements for gas systems, venting, and fire prevention in recreational vehicles.

Maintenance That Heads Off Problems Before They Start

A Girard tankless water heater is a workhorse. It still needs regular attention. Aggregate service data shows most mid-season failures come from neglected cleaning and missed winterization.

Clean the inlet strainer every three months. Debris from your fresh water tank or city supply collects there. A plugged strainer reduces flow below the ignition threshold. You will see lukewarm water or no ignition at all.

Flush the heat exchanger once a year. Mineral scale builds up inside the copper coils. It insulates the water from the heat. Use a submersible pump and a vinegar solution for 45 minutes.

That dissolves scale without harming the unit.

Winterize before the first freeze. The Girard does not have a tank to drain, but it does have a heat exchanger that holds water. Use the bypass kit to pull RV antifreeze through the system. Follow the manufacturer's procedure for the exact model.

Check the exhaust vent each season. Wasps love the protected opening. Use a soft brush to clear the outlet. Confirm the vent cap is secure and free of soot.

Blocked airflow causes short cycling and carbon monoxide risk.

Frequently Asked Questions

How do I reset a Girard tankless water heater?

Turn off the 12V DC power to the unit. Wait 30 seconds. Turn it back on.

This clears error codes from the control board. If the heater still fails, the problem is mechanical, not a software glitch.

Why does my Girard work when connected to city water but not with the pump?

City water pressure is higher. The RV pump may not produce enough flow to spin the flow sensor. Check the pump's output pressure and clean the inline strainer.

A worn pump diaphragm is a common culprit after several seasons.

What does the blinking light mean on my Girard?

It is a diagnostic code. Count the blinks. A repeating pattern corresponds to a specific fault.

The control board label lists the codes. Common ones include low propane pressure, no flow, or overheating.

Can I run my Girard while driving?

No. The unit can shut down due to inconsistent water flow and propane pressure on the road. Use it only when parked with water and gas supplies stable.

This also prevents exhaust fumes from entering the vehicle.

How long should a Girard tankless water heater last?

With regular maintenance, expect 10 to 15 years. The heat exchanger is the critical part. Scale buildup and freezing shorten its life.

As of 2026, replacement parts for the 2GWH series remain widely available through Girard dealers and major RV parts suppliers. Annual flushing and proper winterization are the difference between a decade of service and a replacement.