Is your tankless water heater on the fritz? If you have an old heater or haven’t provided tankless water heater maintenance, you could be left in the cold. There are a few reasons your tankless heater in Evanston might not be working, and a plumber can help. Learn more about the reasons your tankless water heater doesn’t work or heat. 

Water is Lukewarm or Cold

If the water from your taps isn’t hot, you could have one of the following problems:

Too Many Appliances on at Once

Your water heater can only handle so much demand. If you have five different fixtures using hot water, your tankless system may not be able to meet the demand. Pick one or two appliances to use at once and turn off the others. Then, check the hot water again.

If this works, you may need another tankless water heater. The heater you have isn’t able to handle the needs of your household, and the issue will persist. Your best bet is to call an Evanston plumber and ask them for advice. 

Your Minimum Flow Rate 

Every tankless system needs a minimum amount of water to flow before it produces hot water. You could be asking for less than the minimum flow rate, which would prevent your system from kicking on. 

To test this, increase the flow of water from your faucet. Does the water heat up after a few seconds? If so, you just weren’t providing enough of a flow. Most models have a minimum flow rate of .5 gallons each minute. 

Blockage in the System

Your tankless water heater has vents and air intake channels. If one of those components has a clog, your water heater won’t meet your hot water demands. Typically, new water heaters have error codes that warn you of a blocked exhaust vent. 

Another place for a blockage is the burner. But you shouldn’t check the system on your own. Instead, call a plumber and have them check for blockages. 

No Power

As obvious as this may seem, you could overlook this possibility. If you don’t have power to the tankless heater, it won’t work. You may have a tripped breaker or a power outage. In the case of a gas heater, you may need to pay your gas bill, turn on the gas valve, or fill your propane tank. 

The first thing you should always do is look into this problem. Sometimes, flipping a breaker or paying a gas bill is enough to restore your hot water. 

The Weather

Depending on the time of year, the weather could keep you from getting hot water. In the winter, frozen pipes might block water from getting to your appliances or fixtures. 

If this is the cause of your trouble, don’t try to thaw your pipes too quickly. You need to proceed with caution to prevent damage. In the future, you can prevent this problem by insulating your pipes. 

The Water Temperature is Too Hot

If you struggle with water that’s too hot, you could have any of these issues:

Thermostat Set Too High

Your tankless system has a thermostat, and that thermostat could be too high. It should be set around 120 degrees. 

Reduced Water Flow

A blockage in the system could cause the water to become overheated. Once again, do not attempt to fix this on your own. You should work with a professional to identify the issue. 

Water is Hot, Cold, and Hot

If you have a cycle of hot, cold, and hot water, you have a simple problem. Someone may have showered before you, and you get their leftover hot water. Then, the water needs to reheat and comes out cold until it’s at the right temperature. 

This is usually a case of not being able to meet your hot water needs. If you install a point of use heater or get a second tankless heater, you should be able to remedy this. Talk to your plumber and figure out the most effective way to improve your hot water situation. 

Water Smells Like Rotten Eggs

Does your hot water smell like rotten eggs or look discolored? Your water should never have a foul smell. 

Mold or Bacteria

In this case, you could have mold or bacteria in your unit. The odor could come from sulfate bacteria, and this accumulates when warm water sits in the tank for too long. 


Over time, minerals build up in your water tank. These minerals could change the look or smell of your water. Often, minerals result in cloudy or brown water. 

By flushing your tankless heater, you can prevent minerals from accumulating. If you don’t do anything about the minerals, the problem will worsen. Your hot water could stop working entirely. 

Rusty Pipes

If you have a foul smell and rusty color in your water, you could have rusty pipes. This affects your water quality and demands an immediate repair.

Rusty pipes won’t last forever. In fact, they could be weeks away from leaking. Call your plumber for help as soon as possible. 

Leaking Water

When water leaks from your hot water heater, you have a plumbing emergency. Water damage is nothing to ignore. If you have water on your floors or walls, you can be sure that mold will grow. Mold and mildew have a negative impact on your health and will take over your home.

Leaking water could be a result of a poor connection or a broken pipe. Either way, your plumber can address the issue. Clean up any water damage you find to avoid mold growth. 

Call Us for Your Tankless Water Heater Maintenance and Repair

You may be able to prevent trouble with your tankless heater by scheduling annual maintenance. Although tankless heaters need less maintenance than traditional ones, they still need professional attention. 

Whether you need tankless water heater maintenance or a repair, call us at J. Blanton Plumbing. We’re ready to help you with your tankless system in Evanston. Reach out to us today and learn more about what we can do.