What Causes of Water Leakage in Tankless Water Heater? How to Fix?

Tankless water heater considered as a most modern heating device to supply continuous hot water flow. It is also known as an energy efficient ‘green' alternative to tank water heater. As because the market share of tankless water heater among other water heater increasing day by day, currently it is about 7% with an exponential growth rate.

However, uses tankless water heater are triggered furthermore due to imposing of new codes on tank type by the National Appliance Energy Conservation Act of 1987 (NAECA). The cost of new tankless comes much closer to old tank type water heaters over the period. Manufacturer bound to bring continuous improvement in quality due to imposing of new codes by NAECA which directly impact on the cost of purchase. Other hands, the manufacturer of tankless are developing new smaller and economic models which reduce the price day by day.

You may know that to supply hot water, tankless water heater not using any reservoir. Instead, it heats the cold water inflow with a high power burner when it passes through a heat exchanger. So you get instant hot water whenever you need. However, to get uninterrupted flow year over year without any bother you have to take care about proper installation and scheduled maintenance too.

Though as like tank water heater the chances of leakage in tankless is decidedly less still it may happen. Mostly, leakage observes at the bottom and along the connections of the tankless water heaters. Initially, it seems very insignificant, but if you ignore it may turn into catastrophic damage. So, immediate after look out a small leak, it is better to engage an expert plumber in checking the whole thing to avoid a big mess.

Usually, a tankless leak is around 1 GPM, much less than terrible flooding of tank water heater, but still, much water if not contained. As a precaution, it is better to hold leakage water temporarily, and for that, you may install a drain pan which saves you from unwanted large expenses.

Causes of Water Leakage in Tankless Water Heater

We discuss more details about the origins of water leakage in tankless water heater below –

Improper Venting

Ventilation is playing an important role for proper fresh air inflow into the heat exchanger. So, need extra care or professional installation of venting pipes. Lack of adequate venting will cause water leakage, and it is a well-known culprit for tankless water heaters. If venting is not working correctly, it may occur condensation inside the water heater which leads to leakage problems. If condensation is continuing, it might fall the entire system.

Protect condensation, and it is preferable to install power or direct vent or horizontal venting. Keep the vent line as short as possible. Vertical venting is harmful to a tankless water heater.

For better performance, it is wise to follow the manufacturer’s instruction on the venting process.

Water Pipe Connections

The piping connections are flowing the hot water from the tank to fixtures. During its passage, there is several joints and valves are acting. Improver setting or loose connection, any of them may occur during water leakage.

Among valves – relief value is essential and can protect water dripping through the joints. Relief valve customarily set on the hot water outlet from where the pipe is leaving the heater to faucets. Moreover, necessary for flushing or draining the tankless device.

Ensure that all pipes and valve are joint correctly and you set relief valve during installation according to the size of the heater.

Gas Piping

The tankless water heater is an efficient device no doubt. However, to get the maximum efficiency, it needs a dedicated gas line. It is recommended to use a separate gas-line next to meter run directly to water heater without re-running the entire gas main. Put less joint as possible during installation to avoid unnecessary leakage.

Gas leakage may occur significant damage, so immediate after notice takes expert advice and professional repairing.

Acidic and Hard Water

Mineral deposition inside the pipe is not right of any water heater. It creates pressure on heat exchanger which cause overheating. Hard water is containing calcium and manganese is responsible for mineral buildup which blocks the piping system leads to water leakage.

If the pH of your water is less than seven means, the water is acidic. Acidic water effects the meals used for plumbing. It origins pinholes in the tankless water heater and pipes from the heater to fixtures. These pinholes promote leakage in the long run. If the level of pH is much lower than 7, chances of leakage will increase highly.

Water pH is a determinator of necessary or hard water as well as acidic water. So, you have to check the pH level of your supply water. If it is around seven than safe, otherwise need treatment to avoid any damage.

High Water Flow Rate 

One of the primary constraints of tankless water heater is low flow rates and low water pressure. Means it designed for performed in low pressure like 30 psi for household uses. Deposition of debris in showerhead or faucets aerators or inside the heat exchanger creates hindrance of normal water flow which leads to high water pressure. Operate the tankless water heater in high pressure might cause fire up. So need regular flushing and checkup.

How to Fix a Leaking Tankless Water Heater

The following are possible measures to fix water leakage problems of the tankless water heater.

Replacing or Repairing 

Take immediate action to repair the tankless water heater after finding out a leak. If you think, the problem severs enough than you may go for a replacement. Whatever you decide, take an expert opinion before doing so.

Installation of Drain Pan

As a precaution setting a suitable drain pan contained 100% leak in the tankless system. Drain pan protects your property from damage from possible water leakage and saves thousands of dollars in structural repairs, preventing mold issues, etc.

According to the insurance companies, failure of water heater is one of the top five reasons behind water losses. Moreover, 69% of those failures happen due to slow leaks or sudden burst which average monetary value of $4444 per incident.

So, if you still not installed a drain pan for your tankless, do it today.

Contact the Manufacturer

Every device is under cover of warranty, and tankless is no exception. Contact immediately with the manufacturer if you found any leak in the water heater or pipelines for warranty coverage. Typically, all manufacturer offer standard one year warranty for their products, so be careful do not do anything that void the warranty.

The reasons behind the tankless water heater leak are almost similar to the tank types. The leading cause of premature failure is improper installation among other reasons like improper venting, lousy water condition or pumps not working. However, this is not happening for all tankless, and it is not apparent too. Proper servicing & maintenance and professional installation, prolong the life of tankless up to 20 years or more without any leaking problems.

What do I do when my water heater is leaking? [Plumber Solution]

Finally, we can say, tankless will be the best option for your home hot water supply in any aspects as well as its famous for saving your valuable money by consuming less energy.

Common problems that affect Tankless water heaters.
How to fix them?

Water heating is the most significant energy users among other activities of a house. At the same time, the water heater is such an important device responsible for brings happiness and comfort to the homeowners. Beating the drum in favor of tankless water heater is not over amused. As tankless heaters are efficient enough then any other standard heating devices, save energy and save your money too.

The best part of this on-demand heaters is they rarely produce any problem. However, they are not beyond the suspicion of technical hitches. But, these technical hitches are most of the cases self-evident. Like you open the faucet and not get hot water flow. Here we bring up some common tankless water heaters problems in light with a guideline how to fix them.       

  1. Mineral Buildup
  2. Demand overloaded
  3. Cold Water Sandwich
  4. Air supply or Exhaust Blockage
  5. Burner fail to Ignite
  6. Irregular Water Temperature
  7. Bad Smell and Discolor


Mineral Buildup

  • It may happen if the source of water is hard
  • Hard water with high mineral content is potential for mineral buildup
  • Calcium and Magnesium are responsible for the scaly buildup

How to fix

  • Flush water heater in every six months or earlier based on the percentage of mineral content in water with a cleaning kit
  • Use of water softener can slow down the process to an extent


Demand Overload

  • Running multiple showers or use of too much hot water at the same time are liable for this problem.
  • Observe struggling to supply hot water as per demand, or sudden shutdown may occur due to this.

How to fix

  • Try to avoid multiple hot water use in a single moment
  • In case of a sudden shutdown, reset the whole system and restart
  • If it happens more frequently, to fulfill access demand you may replace the current with a larger capacity tankless one or install another parallelly. Though it is a costly option, in the long run, it will save your money.


Cold Water Sandwich

  • You start a shower with hot water, after few moments you feel cold then again get hot water. If you experience like this called ‘Cold Water Sandwich.’
  • It happens due to back to back shower by your family members. The previous member finishes his bath, the hot water still in the pipe, but water heater stops heating, that moment you enter for a shower and turn on the faucet. You will bless with Coldwater sandwich in this case. Though tankless water heaters are a continuous type, it needs few moments to heat up the water and circulate to the faucet.

How to fix

  • If you are already familiar with this problem, be prepared for your next shower. Gap some time if your earlier member finishes his/her shower just now.
  • You may drain out initial waters to allow the heater to start working and supply continuous hot water flow.


Air supply or Exhaust Blockage

  • Due to improper installation or leakage in vent pipe interrupt the combustion air flow or blocked the vent pipe.
  • Fail to maintain proper clearance for air ventilation as per instruction manual or it may too close to other objects that block the air supply, in such case risk of fire hazards.
  • Birds nest, rodents, wasp may also create an obstacle in vent pipe which exposed outside of your home.

How to fix

  • Check the whole vent line thoroughly and clean as per instruction
  • If necessary, you may take help from expert plumbers


Burner fail to Ignite

  • In case of failure of ignition, check the gas supply is on or off.
  • Propane tank is empty or full.
  • Check the gas pressure is enough to ignite the flame or not
  • Check the gas valve and or water valve are fully open or not
  • Check the components for electric short
  • If you found all in the right condition, then it may happen due to the failure of ignition pack

How to fix

  • It is suggested to take expert help to fix it immediately to avoid any further hazards


Irregular Water Temperature (either not hot at all or hot enough)

If you found water is too hot, it may scald your skin

  • Check temperature settings high or not
  • Check thermostat is working correctly or not
  • Water is flowing inside heat exchanger adequately or not

If you found water is not hot enough

  • Maybe you set low temperature, check temp. controller
  • Gas pressure may low if gas operates it
  • Water filter or fixtures aerator may clog

How to fix

  • Fix the temperature in the controller as per your desired
  • Ensure minimum water inflow
  • Fix-up thermostat if not working properly
  • Clean-up deposition inside the heat exchanger, to do this take expert help   


Bed Smell and Discolor

  • If you found strange odor, determine whether it is for the source of water or heater
  • If you found lousy fragrance in both cold and hot water, then it is for source
  • Water containing Iron, Copper or other mineral are liable for discoloration  

How to fix

  • Use filter for the water source or whole house
  • Use of water softener

Regular Maintenance Can Increase the Life of Water Heater. So -

  1. Clean the burner, control components, and vent air passageways
  2. Inspect the flame visually, blue and stable flame are suitable for even heat generation
  3. Keep fan and motor dust free with the help of an air blower
  4. Flush the heat exchanger with an anti-scaling solution in every six months interval
  5. Keep vent exhaust free from other objects like snow, birds nest, etc.  

No doubt tankless water heater is a great device. But nothing is entirely problem free. Regular intensive maintenance can reduce the chance of failure tremendously and increase the lifespan. If necessary do not hesitate to take the expert opinion.

  • Updated 8 months ago
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