6 Common Tankless Water Heater Problems Solved

Tankless hot water heaters can be a great investment for your home or office. Newer versions are very efficient and can save you money if set up properly. Although it’s less common, there are some potential issues that could arise if something isn’t working correctly within the unit. Here are six of the most common problems and maintenance concerns that you could experience with your tankless hot water heater.

  • Mineral Buildup
  • System Overload
  • Cold Water Sandwich
  • Air Supply or Exhaust Blockage Message
  • No Ignition Message
  • Flame Failure Message

Read on to learn about tankless water heater repair, how to fix minor problems and signs to look for in identifying issues with a tankless water heater. Also, check out our blog on how to know when it’s time to replace your water heater.

tankless water heater

Problem 1: Mineral Buildup

Whether you have a tankless hot water heater or a traditional one, you should be aware of mineral buildup inside the unit. The harder your water, the more mineral buildup. The two main culprits are calcium and magnesium, and they create a scaly buildup in the unit that can have damaging effects if not addressed. In order to avoid damage, be sure to flush the hot water heater every year or so. Some models even have sensors that detect the buildup and alert you when it’s time. To get in front of the problem, you can also a water softener to slow the process. Learn more about Robinson’s Personalized Plumbing Prevention Programs.

Problem 2: System Overload

If multiple people in your house are using hot water, or you’re doing several tasks that require hot water then your tankless hot water heater could get overloaded, and either struggle to supply the hot water needed or shut down altogether. If this happens, you’ll want to reduce the high demand for hot water, and even reset your unit. If this happens repeatedly, you might consider upgrading to a larger hot water heater or adding a second unit. Because a second unit means that you’ll use less water while waiting for hot water to arrive and less gas to heat the water, it can actually be cheaper solution in the long run. Find out what features to look for in a new water heater.

Problem 3: A Cold Water Sandwich

A family member of yours just took a shower and a few minutes later it’s your turn. You turn the shower back on and feel warm water after a few seconds, so you hop in. Then it happens. You get blasted with several seconds of cold water before it slowly returns to a bearable temperature. Here’s what happened: When your family member turned the shower off, some of the hot water that was heated was left in the pipes on the way to the shower. When you turn the water back on, you initially get that trapped water. But, the hot water heater takes a few seconds to heat up and it leaves a gap of unheated water just after the trapped water you first received. The further your water has to travel from the hot water heater to its destination, the more noticeable the gap. Then next time you use hot water after it’s just been used, just know that there will likely be a small gap of cold water coming up the pipes. How residential water heater regulations effect gas and hot water costs.

Problem 4. You Get An “Air Supply” or “Exhaust Blockage” Message

A message like this means that your tankless hot water heater is probably having issues with combustion air or venting. First, you can check to make sure the vent pipes are connected properly and don’t appear to have any major holes (a professional can use equipment to detect any small gas leaks that may not be visible). Another common reason for getting this type of message is a blockage of some type, including bird nests, wasp nests, rodents, etc. Even if you can’t see this upon examination, it could be happening inside the fan motor or another part that is difficult to check. Water heater maintenance and safety tips.

Problem 5. You Get A “No Ignition” Message

A “No Ignition” message on your unit means that the hot water heater is trying to light, but for some reason is unable. Typically, the problem is related to gas supply or venting. Potential gas problems include something as simple as an empty propane tank or even an unpaid gas bill. If it’s not as simple as that then you should call your local service provider to come in and assess the situation. Learn about water heater gas line repair and installation.

Problem 6. You Get A “Flame Failure” Message

A “Flame Failure” message means that there’s either a gas pressure problem or an electrical issue. Many times, it has to do with gas pressure. Similar to the “No Ignition” alert, you should first rule out simple problems such as a low propane tank or an unpaid gas bill. If those aren’t the reasons then it could be one of several factors creating a problem with gas pressure. Possible causes include a gas line that’s too small, regulator failure, combustion issues, venting and more. A trained technician can use a tool called a manometer to gauge the gas pressure and locate the problem. If the problem isn’t gas pressure then the flame failure is probably due to an electrical issue. Again, if this is the case then you’ll want to get a professional to come out and take a look. How to decide between gas and electric water heater models.

Having a Tankless Water Heater Problem, But Unsure the Exact Problem?

Tankless hot water heaters tend to be low maintenance and very efficient in the long-run. However, things happen, and sometimes problems can occur. This list includes some of the more common problems that people have with tankless hot water heaters, but it is not all inclusive.

If you don’t see the tankless water heater problem you’re having here, or you want a professional plumbing technician to look at your unit, please schedule an appointment or give us a call at 804-621-7056.

Robinson’s Plumbing Service is a full-service plumber and gas fitting service serving Charlottesville, and Richmond, VA.