repair tankless water heater

Tankless water heaters are not only known for their effectiveness but also for the convenience that they provide users with. However, these systems, which claim to provide an unlimited supply of hot water, can occasionally experience problems that need to be repaired and troubleshooted. Understanding how to repair a tankless water heater will allow you to save time, cut costs, and extend the lifespan of your device.

In this article, we’re looking at the most common problems and understanding how to fix them effectively.

Sediment Buildup in Tankless Water Heaters

One of the most well-known and common issues with tankless water heaters is mineral or sediment buildup, which is mostly caused by hard water. The high mineral concentrations in hard water, like magnesium and calcium, can cause scale to build up inside your heater and reduce its efficiency and effectiveness.

The main reason why hard water tends to accumulate minerals is because it is heated constantly. The heat exchanger, located at the center of a tankless water heater, becomes coated with crystallized dissolved minerals when the water is heated. This buildup affects all interior surfaces of the device.

The accumulation of scale can lead to several issues:

  • Reduced Efficiency: Scale prevents heat from reaching the water, reducing efficiency. Because of this, heat transfer is reduced, the heater has to work harder, and the operational expenses and energy consumption can go up.

  • Decreased Flow Rate: The heater’s capacity to efficiently supply hot water can be compromised if mineral deposits cause the water passageways to become narrower.

  • Equipment Failure: Severe scaling, if left unchecked, can eventually permanently damage the heat exchanger, which could need expensive repairs or perhaps replacement.

  • Turn off the Heater: Make sure the power and water supply of the heater is unplugged before troubleshooting the heater.

  • Prepare Descaling Solution: Either buy one already made or make your own with equal parts water and vinegar. Dissolving the mineral buildup is much easier using this solution.

  • Circulate the Descaling Solution: A submersible pump can be used to circulate the descaling solution throughout the system. After you’ve connected the pump to the service valves, turn it on and wait 45 to 90 minutes, or until the accumulation is no longer noticeable.

  • Flush the System: If there is any solution left over after descaling or minerals that have loosened, flush the system with fresh water through the cold water inlet valve.

  • Check and Clean the Water Filter: Remove the in-line water filter and give it a good cleaning; mineral deposits can also build up there. You can also install a water softener for your heater to make sure this doesn’t happen often.

System Overload in Tankless Water Heaters

When the capacity of a gas or electric tankless water heater is exceeded by the demand for hot water, the system will experience an overload. This is something that can happen in homes that have a lot of water-using equipment running at once.

A tankless heater does not store water but instead, heat it as it runs through the unit. At any moment, the amount of hot water that a unit can deliver is determined by its maximum flow rate, which is expressed in gallons per minute (GPM). Overloading the system occurs when the demand surpasses this capacity and the heater is unable to maintain the desired temperature.

  • Inadequate Hot Water Supply: Overloading the system causes the water heater to fail to provide an acceptable amount of hot water, which means that users will experience water that is either lukewarm or cold when they use it.

  • System Shutdown: In the event of an overload, certain units may power down as a precautionary measure; this might cause inconvenience and disruption to the system.

  • Reset the Heater: To reset the heater, either find the button labeled “reset” or turn off the power at the circuit breaker.

  • Check for Error Codes: If you want to know if you need to fix anything else, you can find the precise error codes in the owner’s manual.

  • Inspect Heating Elements: Overload can cause heating components to break, thus it’s important to inspect them. Find any indications of damage or wear, and if needed, get new ones.

  • Upgrade System Components: If overloads are common, it may be time to upgrade the system’s electrical components or gas supply elements so they can better manage heavy loads.

  • Before purchasing a tankless water heater, measure your home to see how much water it will use. Things to think about include how many people will be living there and how much water will be used at once.

  • Recommend that everyone in the family use hot water appliances at different times. You shouldn’t do things like run the dishwasher and the shower at the same time, for instance.

  • To meet peak water usage without overloading the system, families with high hot water demands may need to install a backup tankless water heater or upgrade to a unit with a higher GPM rating.

The Cold Water Sandwich Effect

One typical issue with tankless water heaters is the “cold water sandwich” effect, which occurs when the consumer is first given hot water, then suddenly gets cold water, and then the water temperature goes back up again.

This water temperature fluctuation effect is caused by the way water is heated in tankless systems. Turning off a hot water tap causes the heater to stop heating water. The newly heated water may not reach the tap immediately after turning on another tap since some cold water may have already been running through the pipes.

  • Initial Hot Water: Assuming all is well with the heater, the first user will receive hot water.

  • Unexpected Drop in Temperature: When the water is turned back on after a short interruption, the next person using the water will first see warm water flow in the pipes, then cold water from the line between the heater and the faucet. This happens because the heater needs time to reheat the water before it can be used again and because the system doesn’t always guarantee endless hot water supply.

  • Return to Hot Water: After the heater starts up, the cold water sandwich comes to an end, and hot water starts flowing again.

  • Install a Buffer Tank: To mitigate the cold water sandwich effect, it is recommended to install a small buffer tank that can hold pre-heated water on a constant basis for your tankless hot water heaters.

  • Troubleshoot the Flow Sensor: A poorly adjusted flow sensor can sometimes make the cold water sandwich worse. Make sure the flow sensor is properly measuring the water’s velocity by checking and adjusting it. Additionally, you can get a temperature sensor to understand the drops and increases in temperature.

  • Upgrade the Recirculation System: If you have an existing recirculation system, you might want to think about upgrading it to something more sophisticated so that the water temperature remains constant.

No Air Flow to or From Tankless Water Heaters

Tankless water heaters, particularly gas ones, need a good air supply and exhaust if they are to work efficiently. To burn fuel and release combustion gases, these heaters require a constant supply of air and must have unobstructed exits. Inefficient operation, safety risks, and system breakdowns can result from blockages in these systems and lead to tankless water heater failures.

  • Debris and Foreign Objects: A common cause of clogs in outdoor units is debris and foreign objects, such as bird nests, insect houses, or collected leaves and twigs.

  • Installation Errors: When vent pipes are improperly installed, they can get bent or kinked, which in turn limits the airflow.

  • Corrosion and Wear: Venting systems are susceptible to degradation and corrosion with time, particularly in extreme weather, which can cause pathways to become more congested and even blocked.

  • Error Codes: Many newer tankless water heaters have codes that show specific issues, including specific codes for a clogged vent.

  • System Shutdowns: In order to avoid potentially dangerous operating situations, the heater may turn off.

  • Inadequate Heating: While partial blockages may not completely shut down the system, they can significantly limit its efficiency, leading to subpar heating performance.

  • Regular Inspections: After storms or seasonal changes, or at any other time, you should check the air intakes and exhaust vents.

  • Professional Maintenance: Get a professional to check and clean the vents in your heater once a year as part of routine maintenance.

  • Clearance Checks: Verify that the installation follows the manufacturer-recommended vent clearances from obstructions like walls, debris, and foliage.

  • Turn off the appliance and gently remove debris, such as leaves or small nests, if the obstruction is simple.

  • When dealing with larger clogs or concerns about possible damage to the venting system, it is best to seek the assistance of a specialist. Damage or safety hazards can worsen as a result of improper handling.

Ignition Failure in Tankless Water Heaters

A major problem with a gas tankless water heater is ignition failure, which can prevent them from starting and leave you without hot water. Fixing this problem might be as easy as turning on the gas and power supply, or it can be as complicated as a component failing.

  • Gas Pressure Problems: If the gas pressure is too low or the valve is closed, ignition will not occur. It could be that the gas meter is locked or that the propane tank is empty.

  • Electrical Issues: Power to electric heaters might be interrupted by a blown fuse or a circuit breaker that has tripped.

  • Problems with Individual Components: Initiators, flame detectors, and control panels that go wrong are typical causes of fires.

  • Check Gas and Power Supplies: Before using your heater, make sure it has an electrical connection and that the gas valve is completely open.

  • Error Codes: Modern units will show codes that can help determine if the problem is with the gas supply or electrical components.

  • Visual Inspection: Examine the components, gas pipelines, and wires visually for any indications of wear or damage

  • Reset the Heater: Turning the heater off and then back on again resets the system, which can occasionally fix electrical problems.

  • Check and Clean the Igniter: Dust and corrosion can build up on the igniter over time. If you clean it, it might work again.

  • Check the Flame Sensor: This device can tell you if the burner is on or off. To avoid gas accumulation, the device might turn off if it detects dirtiness or a malfunction.

  • Turn off the appliance and gently remove debris, such as leaves or small nests, if the obstruction is simple.

  • When dealing with larger clogs or concerns about possible damage to the venting system, it is best to seek the assistance of a specialist. Damage or safety hazards can worsen as a result of improper handling.

It may be required to change the igniter or flame sensor if basic repairs don’t work out for you. The components are affordable, but it may be necessary to hire a professional to install them. This is to guarantee that the unit will be safe and up to code in your area.

Flame Failure in Tankless Water Heaters

Problems with the flame in a tankless water heater can be a sign of more serious problems, the solutions to which can vary from tweaks to the gas pressure to diagnostics of the combustion process.

  • Low Gas Pressure: The burner may not be able to keep a flame going if the gas pressure is too low or there is not a sufficient gas supply. Possible causes of this tankless water heater problem include a partially closed valve, an inadequate supply from the utility, or problems with the regulator.

  • Dirty or Faulty Burner: Proper combustion might be affected by the collection of debris or by a burner that is malfunctioning.

  • Problems with Air Flow: Inadequate ventilation might limit the amount of air needed to keep a fire burning.

  • Monitor the Burner: Be sure to keep an eye on the burner while you’re trying to ignite it. Problems with pressure or supply could be indicated if it flickers or doesn’t stay lit.

  • Check Ventilation: Make sure there is enough air for combustion in the heater and that the vents are clear.

  • Error Codes: Refer to the heater’s manual for a list of error codes that may indicate a problem with the flame.

  • Adjust Gas Pressure: To fine-tune the gas pressure, measure it with a manometer and compare it to the instructions. Modify as needed.

  • Clean or Replace the Burner: If the burner is broken or unclean, you can fix it or replace it to get it working again.

  • Improve Ventilation: Make sure there is adequate outside air to burn fuel and that waste gases can leave the system easily.

Calling a Professional to Fix Your Tankless Water Heater problems

While DIY solutions can handle most tankless water heaters and their basic problems, a professional may be necessary when working with complicated gas or electrical systems or when the issues needs specialized gear.

Comfort Union is an excellent option to consider when looking for HVAC experts in Canada. We provide professional installation, maintenance and repair services for all HVAC systems, with an expertise in tankless water heaters, so that your unit operates at its best and most efficiently. Our skilled HVAC experts are capable of handling any task, from regular maintenance to more intricate repairs, ensuring top-notch service every time.

Reach out to us to know more about our services and repair costs.

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