Signs Your Tankless Water Heater System Needs Repairs

Tankless water heaters are one of the most exciting new pieces of technology in the world of plumbing. They’re more energy-efficient than tank heaters, and they’re surprisingly simple. Their simplicity makes them somewhat less prone to certain problems than traditional tanked heaters – for example, tankless heaters are less likely to develop leaks.


Nonetheless, tankless heaters can develop problems – no machine is perfect, after all. We’re going to take a look at the six most common signs that your tankless heater needs repairs. We’ll also discuss what’s likely to be causing problems with your system. Let’s dive in!

There’s No Hot Water

Obviously, if there’s no hot water coming out of any of your fixtures, there’s almost definitely a problem with your hot water heater. Best case scenario? Someone accidentally flipped the water heater off, or a circuit breaker tripped. 


If everything is on, there could be a host of different problems – ignition failure, flame failure, and a blocked air supply or exhaust are common culprits. Most tankless heaters feature error codes you can consult to find the source of the problem.


You might find that your tankless heater keeps turning off after you turn it on. This will, of course, prevent you from getting any hot water! There are a few possible causes for this, but the most common culprit is a clogged filter. Try replacing or cleaning your filter. If that doesn’t work, call the pros to diagnose the problem.

System overload

Tankless heaters can heat water much more quickly and efficiently than their tanked counterparts. The main disadvantage of tankless heaters is that they have a much lower capacity – they can only heat the quantity of water that flows through them. Run too much hot water at one time, and you’ll find your tankless heater may shut down. To fix this, run fewer hot water-consuming appliances and fixtures at once, or consider installing a higher capacity tankless heater.

The dreaded “cold water sandwich”

A cold-cut sandwich is delicious. A cold water sandwich? Not so much. Here’s the situation: A member of your household gets out of the shower, and you jump right in. You turn on the water. It’s hot at first, so you get into the shower, only to be greeted by an icy blast that could make a polar bear shiver.


What gives? Aren’t tankless heaters supposed to supply hot water on demand?


They are – and they do. What happened here is simple: Cold water started flowing through the pipes when the last person got out of the shower. It became sandwiched between the warm water near the showerhead and the warm water you called for. There’s no problem with your water heater – you just need to wait before jumping into the shower. 

The Water Isn’t Warm Enough

Like traditional gas-tanked heaters, gas tankless heaters use a burner to heat your water. Sediment in your water builds up over time, and that sediment can eventually start blocking heat from the burner. Corrosion and other problems with the burner can also cause your water to be too cool. Don’t crank up the heat on your water heater – you could risk burning yourself. Instead, call a technician. 

The Water Pressure Has Taken a Dip

The sediment we just talked about? It can be particularly problematic for tankless heaters. Given how much smaller they are than tanked heaters, sediment build-up happens quickly. That’s part of the reason regular maintenance is so important and part of the reason you should regularly change or clean your tankless heater’s filter. 


If your cold water pressure is fine, but your hot water pressure is low, you’ll need to call someone to clean your tankless heater. 

There’s a Leak

Your heater might have a loose or broken valve or fitting. Obviously, if your water heater is leaking, you’ll want to call a plumber. More often than not, leaks on tankless heaters are relatively simple for plumbers to fix. 

Your Water Heater Is Making Strange Noises

Ticking, tapping, and clicking noises aren’t unusual. They’re caused by heat traps and check valves. Humming, hammering, hissing, screeching, and other loud noises, on the other hand, are signs that something has gone wrong. Parts may be loose, pipes may not be anchored securely – strange noises can be the sign of all kinds of problems. Call a plumber. 

Other Appliances Aren’t Working as Well as They Used To

This only applies to appliances that use hot water, like your dishwasher or your washing machine. If you find that all of your hot water-consuming appliances have stopped working as well, it’s likely a problem with your tankless heater. Insufficient heat could lead to clothes and dishes not being completely clean.


Tankless water heaters are incredibly reliable, and they don’t tend to need repairs very often – especially when you’re getting routine maintenance. When problems do arise, it’s best to call for a plumber right away. We offer plumbing in Winnipeg, including tankless heater installation, repair, and maintenance. Need a hand with your water heater? Give us a call.