6 Common Tankless Water-Heater Problems and Solutions

You switched to a tankless water heater because you were tired of running out of hot water. No more cold showers. No more fighting with your family over who gets to shower first. Endless hot water, right?

Except now, for some reason, your tankless water heater isn’t working as expected.

Here’s the thing: tankless water heaters are reliable and designed to last 20 years or more with proper tankless water heater maintenance services. But like any equipment in your home, they can develop problems. Fortunately, most of those problems are usually simple to fix.

In this blog, we will walk through the six most common tankless water heater problems Sacramento homeowners face, how to spot them, and what you can do about them.

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Problem 1: Mineral Buildup

What it is: Minerals like calcium and magnesium in your water can build up inside your tankless water heater over time, especially in areas with hard water.

What to notice:

• Your water takes longer to heat.
• You are not getting the same hot water flow you once did.
• The unit makes strange noises.
• Your energy bills have gone up.

Why it happens: Tankless water heaters have a heat exchanger with narrow pathways. When hard water flows through these pathways, minerals can stick to the surfaces and build up over time. Traditional tank water heaters don’t have this problem as severely because they hold a large volume of water, which dilutes the mineral concentration.

Solution

You should flush your tankless water heater every six months using a descaling solution or opt for professional tankless water heater maintenance services.

If you have hard water in your area, you should install a water softener, as it will slow down the buildup significantly.

Sacramento’s water quality is actually better than in most parts of the country, but it still contains minerals. If you’re on well water in the greater Sacramento area, you should also consider scale buildup.

Problem 2: System Overload

What it is: Your tankless water heater has a maximum flow rate, which is the amount of hot water it can deliver at any moment. But if you try to use more hot water than the unit can handle, it gets overloaded.

What to notice:

• The water temperature drops once a second faucet is turned on.
• You run out of hot water when the other shower starts.
• The unit shuts off during heavy use.

Why it happens: You’re using more hot water than your unit can produce. This is common in larger households or homes with multiple bathrooms. For example, if you are taking a shower (2.5 GPM) and someone turns on the washing machine (2.0 GPM) and the dishwasher (1.5 GPM) at the same time, you might be asking for 6.0 GPM from a unit that can only deliver 5.0 GPM.

Solution

The short-term fix is simple: stagger your hot water usage. Run the dishwasher at night instead of in the morning. Avoid doing laundry when everyone is showering.

But if this keeps happening, then the real solution is to upgrade to a unit with a higher flow rate or add a second unit to handle the demand.

Most homes, especially newer ones, have multiple bathrooms and modern appliances. If your tankless unit was installed before you renovated your laundry room, it might not be able to keep up with your current water demands.

Problem 3: Cold Water Sandwich

What it is: You’re in the shower, the water is perfectly hot, and then BAM! a burst of cold water hits you, but a few seconds later, the hot water comes back. This is the cold-water sandwich.

What to notice:

• Sudden bursts of cold water in the middle of a shower
• The cold water happens when you turn the water off and back on.
• The problem is worse when you use hot water intermittently.

Why it happens: Tankless water heaters only heat water when there is a demand. Once you shut off the hot water, the unit also shuts down. When you turn it back on, there’s still cold water waiting in the pipes between the heater and your showerhead. That cold water has to clear out before the newly heated water reaches you.

Solution

The best solution is installing a recirculation pump, which keeps a small amount of hot water moving through your pipes, to prevent cold water from sitting around waiting to surprise you.

Another option is a buffer tank, which is a small storage tank that holds a few gallons of hot water and smooths out the temperature changes.

Problem 4: Water Temperature Fluctuations

What it is: Your water temperature keeps fluctuating, and you are unable to find a consistent temperature.

What to notice:

• The shower temperature changes on its own.
• You are constantly adjusting the handle to find the perfect temperature.
• Different faucets in your home have wildly different water temperatures.

Why it happens: The most common cause is a malfunctioning water flow sensor, which is not working correctly, and your unit cannot regulate the water temperature properly.

External temperature changes can also play a part when your pipes run through uninsulated spaces. Here, the cold weather can cool the water before it reaches your fixtures.

Solution

Start by having a professional check the water flow sensor if it’s faulty. You can also insulate any exposed pipes, especially in crawl spaces, attics, or garages, to maintain a more stable water temperature as the water travels.

Regular checks by a professional can help diagnose problems before they affect your comfort.

Problem 5: Long Wait for Hot Water

What it is: You turn on the hot water faucet and wait forever before hot water finally arrives.

What to notice:

• It takes 30 seconds or more to get hot water at your faucets.
• The problem is worse at fixtures away from the water heater.
• You are wasting water waiting for it to heat up.

Why it happens: The distance between your tankless water heater and your faucet is too long. Hence, the water has to travel across long pipes. Also, there is no recirculation system to keep hot water moving.

This is especially common in larger homes where the water heater is installed away from the bathrooms.

Solution

The best solution is to install a recirculation pump. For a more targeted approach, a point-of-use heater installed near specific fixtures like sinks or showers can provide instant hot water without the wait.

Homes come in a variety of styles, from older bungalows to sprawling suburban houses. The farther your fixtures are from your water heater, the longer you’ll wait for hot water.

Problem 6: Inadequate Heating Capacity

What it is: Your tankless water heater is running, but the water just isn’t getting hot enough.

What to notice:

• The water is warm but never quite hot.
• You have turned the temperature setting to maximum, and it’s still not enough.
• The problem is worse in winter.

Why it happens: This usually happens either because your unit is undersized for your home, doesn’t have the capacity to heat the amount of water you need, or has incorrect system settings.

Solution:

Make sure the temperature is set correctly and that nothing is affecting the unit’s performance. If the problem continues, you need to upgrade to a larger unit. This is especially important if you have added family members recently, new appliances, or additional bathrooms since your water heater was installed.

Questions Clients Ask

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Takeaway

Tankless water heaters are one of the best investments you can make for your Sacramento home. These are efficient, space-saving, and provide endless hot water when working correctly. But like any piece of equipment, they require the right care and attention.

We have covered the six major problems in a tankless water heater: mineral buildup, system overload, cold water sandwich, temperature fluctuations, long wait times, and inadequate heating capacity. Some of these issues can be handled yourself, while others require professional tankless water heater repair services.

The main idea is not to ignore the problem because small issues can become big problems if left unchecked.

Read More About:

1. Why Water Heaters Fail Suddenly (Without Warning Signs)
2. Why Your Water Heater Runs Out of Hot Water Fast
3. Is Hard Water Killing Your Water Heater?
4. What to Consider When Planning a Water Heater Installation

Don’t Allow Tankless Water Heater Problems to Ruin Your Comfort – Contact the Water Heater Man

At The Water Heater Man, we specialize in keeping tankless water heaters running at peak performance. Our range of tankless water heater services in Sacramento includes:

• Water heater repair – Fast, reliable fixes when something goes wrong
• Water heater replacement & new installation – Expert installation of the right unit
• Water heater maintenance – Keeping your system running smoothly to extend its life
• Tankless water heater service Sacramento – Installation, repair, and maintenance of high-efficiency tankless systems

We proudly serve our clients across the greater Sacramento Area –

• Rocklin
• Roseville
• Granite Bay
• Lincoln

No matter where you are, we’re the best water heater company that brings the same level of expertise and personalized service to every job. Call us at 916-215-0030.