How to Detect Bosch Tankless Water Heater Leaking with 5 Reasons

Why Bosch tankless water heater leaking?The pH level in your sewerage water can severely affect water leaking. Even faulty venting systems can damage Bosch tankless water heaters and permanently damage them.

Most people think that leaking in a tankless heater sounds impossible, but it certainly can. Leaking is one of the common problems for both tank and tankless water heaters. Bosch undoubtedly makes one of the best tankless water heaters, but even great products sometimes malfunction. Let’s find out the leaking factors discussed below:

Reasons Why Bosch Tankless Water Heater Leaking

  Reasons  Solutions
Improper InstallationReinstall the tankless water heater correctly
Heavy Rust DepositThe entire water heater pipe system replaced
Poor Water ConditionsInstalling pH neutralizer
Faulty Venting SystemCall a professional
Blocked Inlet & Outlet PipesClear the blockage or hire an expert to do it
High Water Flow RateClean and remove debris

Reason 1: Improper Installation

Most Bosch tankless water heaters come in different models and systems with new updates. Even though the installation process of any tankless water heater is the same, some Bosch heaters need customized installation.

One of the common reasons for the Bosch tankless heater leaking is installing it incorrectly in the first place. Check out if the stud finder in your heater has one inch per distance from the wall. The next thing to follow is to measure if the outlet pipe has a solid connection with the heater pipeline. The unit lines should have shut-off valves installed close to ¼ inches.

READ ALSO  Where Should Water Hammer Arrestors Be Installed

If any of these are not appropriately maintained, these are apparent symptoms that your bosch tankless heater wasn’t correctly installed. For a bosch tankless electric water heater, check the electric valve instead of the shutoff valve.

Reason 2: Heavy Rust Deposit

Rust deposit tends to happen in an older Bosch tankless water heater. Sometimes when a tankless heater gets old, rust or sediment appears inside the main pipes of the heater.

A layer of calcium carbonate mainly forms a thick coat inside the shutoff or electric valve. The common symptoms are water heating taking longer than regular and leaking. When sediments or rust appear, the pipes get narrower, and Bosch tankless heater needs to work harder to heat water and bring it through the lines. You’ll notice your water heater gradually losing its efficiency.

The leak is undoubtedly due to rust if the heater’s interior lining has been damaged. Also, if the heater floods even before you detect the leak, it is due to rust. The final symptom is that the leak appears from the main heater, not any adjacent pipe.

Reason 3: Poor Water Conditions

Sediments lead to the following reason that is water pH level. Water conditions of your plumbing system play a significant role in leakage. Acid water or water with less than seven pH levels can tamper your pipes. That includes Bosch tankless water heater inner pipes and your plumbing system pipes.

After detecting a leak, if you see that your sink or bathtub has a blur or green stain, it is a clear indicator that the cause is Acidic water. The water is too hard or acidic, indicating that your area has bad water conditions.

Hard water or ph>7 can dissolve minerals into the inner valve of the water heater. Mostly the rust is due to hard water. Also, if you see the water is overheating than usual amidst leaks. In that case, it is due to the excess hardness of the water.

Reason 4: Faulty Venting System

Bosch tankless water Heater thermocouple includes a gas sensor to replace regular gas tanks of standard bosch heaters. The sensor works in cooperating with the venting system. The common symptoms are seeing gas stain on bathroom walls and roofs. Also, besides your house, you’ll detect gas leaks inside your home or stains inside your house walls or ceilings.

READ ALSO  Is Water Heater Exhaust Pipe Very Hot? Know reasons with Solutions

A faulty venting system leak is the most dangerous among the other reasons we’ve mentioned here. It can lead to a fire accident.

Improper venting systems lead to condensation of the Bosch shutoff valve, leading to valve leak. Ultimately it results in a water leak. Shutoff valves not functioning correctly or water heaters not working completely indicates venting system leak.

Reason 5: Blocked Inlet & Outlet Pipes

Bosch tankless heater draws gas, electricity, and propane from the home power unit. If you use a gas-powered Bosch tankless water, then there’s a need for an extra pipeline to extract the gas from your home.

There’s a high gas leak if the heater’s entry point and the piper’s outer part have a blockage. Again the symptoms are gas stains and also your sewerage system malfunction.

Sometimes birds make nests in the outlet of the pipes which also leads to leaks. It affects the bosch gas sensor, and without detecting proper gas management, the tankless heater can lose its efficiency. That leads to a potential leak. In severe cases, Bosch thermocouple fails to show gas sensor malfunction message at its control panel.

Reason 5: High Water Flow Rate

The last reason is your plumbing system’s very high-pressure water or flow rate. A tankless water heater can leak if water flow goes above 30 PSI. Also, if the water pressure is more than 200 kPa, then your Bosch heater can leak.

If you see a leak and too much water pressure and flow in your plumbing system, the reason is high water pressure. Very high pressure and water flow rate often create excess pressure in the heating valve than it can take. Gradually, the valve loses its functionality, and the constant heating diseases its capacity. This leads to a potential leak.

Moreover, the water flow can slow down if you don’t remove the debris from your showerhead or faucet aerator. Bosch tankless water heater needs low water flow rate but too slow can tamper its primary function., It also results in leaks due to excessive slow water pressure.

READ ALSO  Can You Braze Over a Solder Joint? Don’t Miss It!

This Video Will Help You Too!

Frequently Asked Questions (FAQs)

Why is My Tankless Water Heater Leaking?

There are many reasons, including wrong installation, high water pressure, gas leak, and more discussed above.

How Long Does A Bosch Tankless Water Heater Last?

Bosch claims that their tankless water heater lasts 20 years. It can last less or more depending on your use. If the heater has proper maintenance and is endorsed by a professional monthly, it can go up to 40 to 45 years.

Does Bosch Water Heater Have A Pump?

Yes, Bosch tankless water heaters include a Built-in recirculation pump for temperature stability.


Some leaks are harmful and some harmless, but it’s always safe to detect the leak quickly and take action. Most tankless water heaters, including Bosch, include a relief valve on the heated water discharge pipe. The relief valve usually prevents leaking. If that pipe troubleshoots, that can also be a reason for your bosch tankless water heater leaking.

Lastly, if your Bosch heater doesn’t have any of the symptoms mentioned above, it’s highly advisable to contact a professional.

You Can Also Read:

Check out our Reusable Bamboora Paper Cloth Towels

While shaping the aim of making the environment clean and healthy, Bamboora deals with the production of natures way bamboo paper cloth towels. These bamboo towels are better for the environment.
Along with doing lots of plumbing work, they are usable for other house chores too. From wiping out the spill on the floor to cleaning the dust, bamboo paper towels effectively perform their work. They are effective in replacing regular cloth towels that you often purchase. The natural strength and softest fiber of bamboo make them one of the best sustainable bamboo paper towels.

Similar Posts