What temperature should a tankless water heater be set at

Wondering how hot you should set your water heater? Once you buy a water heater unit, the factory usually presets its temperature. However, that doesn’t mean you can’t have control of its temperature. Here’s the good news: you can adjust the temperature that suits you to ensure your family’s safety.

Previously, we published an article talking about the sudden change in your shower’s temperature. One of the reasons is the problem that might occur with your water heater. The temperature of the unit does matter because it can affect how it functions.

For this blog, we will talk about the risk of setting the temperature too high and too low and the ideal temperature for your water heater to function well.

Top Risks of setting your unit temperature too high

An experienced plumber would say that setting your unit too high can pose a potential threat to your children’s safety. It can also affect your bills and the heater itself. To guide you, we explained the following risks:

1. Scalding Accidents

Setting the temperature too high can cause scalding accidents leading to burns. A study about water heater temperature and characteristics stated that many water heaters are often set dangerously high.

The Centers for Disease Control and Prevention (CDC) found that Younger children’s injuries are most likely sustained from scald burns. Over 300 children ages 0 to 19 are treated in emergency rooms for burn-related injuries every day, and two of these children die due to being burned.

Experts strongly advised having your water heater tested to avoid tap burns. These accidents can be avoided by letting your water run for three minutes then checking the temperature using a candy thermometer.

2. High electricity bill

Warning: A water heater set too high can skyrocket your energy bill!

According to the Department of Energy, your water heater can waste between $36 to $61 yearly due to standby heat losses. The good news is, you can save between 4% to 22% of your yearly energy bill if you lower your temperature.

Lowering your water heater temperature can reduce standby heat loss, which is why you have a high energy bill.

3. Lowers your unit’s service life

It is said that water with high temperatures can fasten the accumulation of hard water mineral sediment, especially calcium carbonate, inside the tank. The accumulation can trigger water heater tank corrosion, resulting in the shortening of the expected lifespan of the entire unit.

The rust buildup in the tank can also result in leaks and contaminated water. The accumulation of rust inside is one of the main reasons the water heater breaks down.

To expand your water heater’s lifespan up to 12 years, we recommend doing annual water heater maintenance. We published an article on why and how you can increase its lifespan. See the article here.

Risk of setting your unit temperature too low

On the flip side, you won’t want to set the temperature of your unit too low. If you do, it can lead to a health issue.

1. Legionnaires disease

Every year, close to 100 Americans are hospitalized for a type of bacterial infection that can be caused by water heaters. Up to 12% of its death rates came from the illnesses associated with the bacteria.

The said illness is a form of atypical pneumonia caused by the Legionella bacteria. This bacteria is found in water at low temperatures – usually between 20-45 degrees celsius. You can get the disease when you breathe in tiny water droplets in the air where the bacteria is present. That said, residential water heating influences the growth of these bacteria.

Evidence shows that the transmission of this bacteria mostly came from drinking water distribution in private homes. Thus, there are more chances people can get sick, especially the elderly, smokers, sickly patients, and patients with chronic respiratory illnesses such as asthma.

It is found that the risk of contamination is much lower for water heaters set at 60°C or 140°F.

Ideal Temperature For Your Water Heater

The ideal temperature is…

As for the ideal temperature, here’s what different agencies have to say:

The Occupational Safety and Health Administration (OSHA) and the World Health Organization (WHO) says that water heaters maintained below 60°C (140°F) may foster Legionella growth. However, this temperature will likely increase the chance of getting burned by scalding hot water.
The CDC and the Energy Department say to set your water heater’s thermostat to 120°F or lower if you have small children at home. This is to maintain a constant thermostat setting that can help control the water temperature throughout your home—preventing it from getting too high.

So, is it 120°F or 140°F?

We recommend setting the temperature anywhere within 120 to 140°F. However, you can set your water heater temperature between 130 to 140°F, especially for large water heaters used in hospitals and industrial settings.

If you have children at home, set it to 120°F as this is safe to the majority of the population.

Your installer can help you adjust your water heater temperature.

As part of our service, our licensed technician at SPS Plumber can help you set your water heater to the right temperature. We also provide annual water heater maintenance for your unit. Call us at 408-622-8183 (South Bay Area) or 209-597-9107 (Central Valley) to book an appointment today!

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