Tankless Water Heaters – Common Questions and Concerns


Tankless water heating has become increasingly popular in the U.S. for residential water heating systems because of its effectiveness and sustainability. The majority of tankless systems run on natural gas, with others being electric. Also called on-demand or spontaneous water heaters, these units heat water only when it is needed in the home. This can reduce energy consumption and take up less space compared to a standard tank water heater. Here are some frequently asked questions regarding tankless water heaters.

Dangers of tankless water heaters – Are tankless water heaters dangerous?

The number one reason people get tankless water heaters is to save energy and money. But with these savings comes an added risk. Are there dangers of tankless water heaters? Well yes, the biggest danger comes from the fact that the tankless water heater uses natural gas. All appliances in the home that use natural gas come with a risk of carbon monoxide poisoning. To reduce these risks, it’s recommended you install at least two carbon monoxide detectors in your home.

Why is my tankless water heater not getting hot?

So you’ve got your tankless water heater but have no hot water. What could be going wrong? Well, firstly, take note of how much hot water you’ve been using in a short amount of time. Depending on your tankless water heater’s capacity, too many simultaneous hot water usages can overload and stress your water heater. If discontinuation of hot water applications (such as showers, washing machine, dishwasher) does not solve the issue, you may need to reset your unit. If this issue becomes frequent, consider upgrading to a larger capacity unit or adding a second unit. It’s also recommended that you do not use hot water back to back, such as family members using the shower one after the other. Although tankless water heaters are thought of as being “instant” this is not the case as they still take time to heat water, so don’t expect a never ending supply of hot water coming out.

Other issues that could be causing your tankless water heater to not heat water include blocked air supply/exhaust, ignition failure (often caused by gas supply), or flame failure. Check with your gas company to ensure you have sufficient gas pressure, correct gas line size, and correct positioning of your propane tank. These simple fixes can cause big issues with your tankless water heater, so it’s important that you make sure you are all set up.

Should I turn off my electric water heater if the water is off?

If you are turning off your main water supply to the house, then yes, you should turn off your water heater. Failure to do so could lead to dangerous pressure build up if the relief valve fails. If the heating element is on with low water levels, then it gets too hot and burns up. These dangers mostly apply to tank based water heaters, but it is still recommended to turn off your tankless heater if you are going to be leaving for an extended amount of time. Overall, it’s not recommended that you turn your water off at all (unless absolutely necessary) as turning the water off and on frequently can cause pressure issues that stress your entire system.

Does turning off your water heater save electricity?

Water heating systems are the second biggest sources of electricity consumption in the home. You can turn your water heater off and save up to 10% on your electric bill. This is because conventional tank based water heaters are not 100% insulated, and some heat loss DOES occur. So consider turning your water heater off when you know you aren’t going to be using hot water for a while.

Thankfully, tankless water heaters don’t have standby heat losses, and this is one reason why they are around 30% more energy efficient than standard tank water heaters. However, this doesn’t mean tankless water heaters can’t waste energy. If they have a constantly burning pilot light, the energy savings can slowly dwindle. The cost of operating a pilot light varies according to the model of the tankless water heater. If you buy a model with a standing pilot light, you can turn it off when it’s not in use. Also consider getting a tankless water heater that uses an IID (intermittent ignition device) instead of a standing pilot light.

In conclusion, tankless water heaters are low maintenance for the most part, and extremely efficient but this doesn’t mean they are exempt from problems. The cost of a tankless water heater is more expensive than conventional water heaters, but the tankless version will likely last longer and be cheaper in the long run. Most tankless water heaters last 20 years and have easily replaceable parts, making them a great addition for any home.