No Water from Tankless Heater? Try This Before Calling a Plumber

As I turned on my faucet expecting a steady stream of hot water for my morning coffee, nothing came out but a few drips. My tankless water heater had been working flawlessly for years, so this lack of flow was unusual. Before making an expensive service call, I did some troubleshooting to get my hot water flowing again.

Tankless heaters, which heat water instantly rather than storing it, can develop winter-specific issues that prevent water from coming out. Frozen pipes and frozen gas regulators are common culprits. Understanding the underlying causes can help you safely fix the problem yourself.

Why Has My Tankless Water Heater Stopped Producing Hot Water?

Overview of Common Causes

If no water is coming from your tankless heater, it's typically due to:

• Frozen pipes - In frigid temperatures, water inside pipes can freeze, blocking flow
• Frozen LP gas regulator - The regulator controlling gas flow to the heater can ice up

Symptoms to Look For

How do you know if one of these issues is behind your tankless water heater problem? Here are a few key symptoms to check for:

• No hot water at faucets - The main red flag is a total lack of hot water
• Error code 12 - This code often appears if the gas regulator has frozen
• Visible ice on pipes - You may see frost or ice buildup on the water lines

Could My Pipes Be Frozen? How to Check and Thaw Safely

Inspect Pipes for Ice Blockages

Start by visually checking all exposed water pipes leading to and from the heater for ice. Shine a flashlight along their length to better see any frosty blockages. Also check joints and elbows which can be prone to freezing.

Narrow down the location where water stops flowing to determine which section needs thawing. Turn on multiple faucets while observing pipes. If water sputters out somewhere along the pipe's run before it reaches the faucet, focus thawing efforts there.

Close Vents Preventing Heat Circulation

Ensure appliance compartments and crawl spaces haven't been losing precious warm air through open vents. Vents in enclosed areas like these should remain closed during frigid weather to keep ambient temperatures slightly warmer.

Colder surrounding temperatures make pipes more prone to freezing. Verify vents near your water heater are shut tight once colder months hit.

Use a Hair Dryer to Gently Heat Icy Sections

Never use an open flame or high heat to thaw pipes. This can damage the pipe and intensify freezing. Instead, use a hair dryer on the low setting. Gently move it back and forth over icy sections of pipe.

Also avoid excess pressure on frozen pipes as they thaw or re-freezing melted sections before water can drain. Both can cause cracks and leaks.

Turn Water Supply Back On Slowly Once Thawed

After thawing your pipes, don't rush to flip the main water switch back on. First, inspect previously frozen sections closely. Ensure no cracks have formed and joints seem intact. Water should flow freely when tapped lightly.

Once you've verified integrity, slowly turn the main valve back on. Start with slightly open, then gradually increase water volume over several minutes. This reduces risk of pipe bursts.

Is My LP Gas Regulator Frozen? Detecting and Clearing Ice

Call Gas Company to Inject Methanol

For tankless units relying on propane gas, regulators can freeze just like pipes. Have your gas company inject methanol into the propane tank to lower its freeze point below your area's temperatures.

Adding methanol prevents cold temperatures from freezing the moisture in pipes and regulator. This step safeguards against error 12 codes and no-flow situations.

Check Exterior Regulator Box for Ice

Your propane tank's regulator will be housed in a box or enclosure somewhere outside. Inspect it, looking closely for ice. A layer of frost around the regulator indicates freezing may be preventing gas from flowing.

Use indirect heat like a hairdryer or heat lamp to gently loosen ice if present. Never pry frozen regulators.

Restart Heater Once Regulator is Defrosted

After visually confirming your propane regulator box is ice free, restart your tankless unit per its documentation. It should ignite its burner and resume heating water.

If your heater still won't fire up, avoid repeated restart attempts. Call your propane company or a technician instead. The issue may require more involved troubleshooting.

Preventing Future Freezing Problems with Your Tankless Heater

While inconvenient, frozen tankless heaters can often be thawed safely without calling a professional. But it's better to avoid the issue altogether. Here are some steps to prevent repeat freezing incidents:

Adjustments to Stop Pipes Freezing

• Insulate water pipes in unheated areas
• Seal any drafty windows/doors allowing cold inside
• Let indoor faucets drip during extreme cold snaps
• Keep cabinet doors under sinks open

Keeping LP Gas Regulator from Icing Up Again

Work with your propane company to:

• Add sufficient methanol before winter
• Install regulator heater/heat tape accessories
• Upgrade to a freeze-resistant model if needed

Preparing Unit for Extreme Cold Snaps

When your weather forecast predicts record lows:

• Cover the exterior of your heater
• Close vents allowing cold direct access
• Check methanol levels in propane tank
• Verify water valves before pipes freeze

When to Call a Professional for Tankless Water Heater Issues

While many tankless heater problems in winter are avoidable, it's safest hiring a pro if you:

If Pipes Have Already Burst

Don't attempt pipe repairs without training and tools. Severe bursts causing flooding require immediate water shut off.

Complex Gas Line Defrosting Needed

Allow gas technicians to handle substantial ice in regulator boxes or gas piping. Attempting removal risks valve damage or gas leaks.

Ongoing Cold Weather Problems

If you continually lose hot water every winter despite preventive steps, have the system evaluated. Upgrades may be needed.

What temperature can cause freezing?

Any temperature below 32deg F has potential to freeze water pipes and moisture inside regulators. Use preventive measures once temps drop near freezing.

Are tankless heaters more prone to winter problems?

Indirect tankless units relying on electricity instead of gas have fewer cold weather-related issues. But any system with exposure can develop ice blockages halting water flow.

Should I fully drain pipes before extreme cold?

Draining entire plumbing systems can introduce oxygen promoting corrosion over time. Focus on insulation, drip faucets, and sealing cold air leaks instead before bitter cold sets in.