Common Tankless Water Heater Problems and How to Solve Them

Tankless water heaters are an excellent choice for fast, accessible hot water. However, tankless water heaters can run into issues from daily wear and tear like any home appliance. While professionals should do most repairs for tankless water heaters, there are some that you can do yourself. Keep reading for a few common tankless water heater problems and how to solve them.


System Overload

Though tankless water heaters are pretty efficient at doing their job, they can overload the system. If you’re using more hot water than your water heater can handle, the heater may shut down.

Try This: Be careful not to overload the system by running several hot water taps simultaneously. In other words, avoid taking a hot bath and running the dishwasher at the same time. If this is unavoidable, or you have a large household, try replacing your unit with a larger one or adding another unit.


Mineral Buildup

Depending on your location, your water supply may be heavy with mineral content. This is known as “hard water” and can leave mineral residue through constant use. The same scale that dims your shower fixtures can build up inside the water heater and decrease its efficiency.

Try This: Use a specialized descaling product to flush your system every six months or so. Alternatively, you can add a water softener to slow down the buildup process.


Blocked Air Supply or Exhaust

A tankless water heater has several vents to allow air in and out. If your system indicates that air is blocked, it won’t work correctly until the issue is corrected. For example, there could be punctures in vent pipes or natural obstructions at outdoor vents.

Try This: If you receive an error on the air supply or exhaust, inspect vent pipes for improper connection or holes/tears. Then, make sure that any items near the unit are cleared away. Finally, check outdoor vents for bird nests, leaves, or other organic matter. Once you’ve removed all blockages, a simple restart should correct the error.

Prevention is critical, so try to do a round of inspections on the unit every few weeks, especially during cooler months or bad weather when birds, rodents, and pests seek shelter.


Ignition Failure

If your tankless water heater isn’t igniting, the most likely culprit is an empty gas tank. Another cause could be water or gas valves that aren’t opened all the way.

Try This: Check the gas tank to make sure you have enough fuel. Then, make sure that all valves are completely open. If the unit still doesn’t ignite, call a professional.


If you’re not quite sure how to tackle your tankless water heater’s problem, give the pros at High-Efficiency LLC a call. Our water heater experts will be able to diagnose and resolve any of these common (and some not-so-common) problems.