Frequently Asked Questions – Hot Water Cylinder Temperature

Hot Water Cylinder NZ

Some of the most frequent questions we get asked about hot water cylinders, and water heating revolve around the ideal hot water cylinder temperature for your home.

Is there an ideal temperature you should set your hot water at? Can you actually change the temperature of the water in your hot water cylinder? Are there risks if your water is too hot or not hot enough?

Yes, yes, and yes! Hot water cylinder temperature is extremely important for many reasons.

Why does the water temperature matter?

If you use a hot water cylinder as your hot water heating method. You will have a cylinder full of water that gets heated and stays at that heated temperature until you use it. Furthermore, if your hot water cylinder is a 280L one. For example, you will have 280 litres that get heated and stay at that temperature while the water sits in the cylinder. (This is different for a gas continuous flow hot water system, where your water is heated as you use it.) Therefore, it is vital that the water in your hot water cylinder gets heated to the correct temperature.

If your water is not hot enough…

If the hot water cylinder temperature and water in your hot water cylinder are not hot enough. Unfortunately, you run the risk of people in your household getting very sick.

You should store water in a hot water cylinder at around 60 degrees Celsius to prevent the risk of harmful bacteria. For instance, bacteria like legionella from growing in the cylinder or its parts. There’s no need to keep the water any hotter than this.

The New Zealand Building Code specifies the minimum and maximums that must be adhered to. Hence, we recommend you contact us to check that you comply with these guidelines.

If your water is too hot…

Water that comes out of your taps at 55 degrees Celsius or hotter can be pretty dangerous. As a result, causing severe burns and scalding in just seconds. (A scald is just another way of referring to a burn caused by something wet.) Consequently, elderly people and children are at greater risk of hot water burns. This is due to greater sensitivity (thinner skin) and possible slower reaction times.

Therefore, while it’s important to heat and store your water to 60 degrees. You should have a tempering valve on your hot water cylinder. This will control how hot the water is when it comes out of your taps.

The New Zealand Ministry of Education provides the following guidance for education centres regarding water temperature that is safe for children. “The temperature of warm water delivered from any taps that children can access independently is no higher than 40°C.” The Ministry also states that “The Regional Public Health recommendation is that water should ideally be delivered at a temperature between 37ºC and 40ºC wherever children have access.”

We’ve included this information to emphasise the point that water coming out of your taps at too high a temperature can be extremely dangerous for children (and others) in the house.

How do you make sure it’s hot enough but not too hot?

Therefore, the key to having the ideal water temperature is to have a tempering valve on your hot water cylinder. Which all modern cylinders now have.

A tempering valve works as a mixing tool to combine hot and cold water to produce the required water temperature to be released.

This means you can have the water in your hot water cylinder hot enough to ward off bacteria and legionella (at least 60 degrees Celsius). While having it delivered to your taps at a safer temperature (closer to 40 degrees).

How do you change the temperature of your hot water cylinder?

The thermostat controls the water temperature in your hot water cylinder. You can locate the thermostat on the side of the cylinder. The New Zealand Building Code stipulates the minimum temperature at which hot water cylinders in New Zealand residences must be set at. Hence, if you need to have your hot water thermostat adjusted. We advise that a qualified tradesperson do this for you. Give us a call if you believe yours needs adjusting.

Additionally, if your hot water cylinder is old and you suspect the thermostat may not be accurate. You can always check the water temperature that comes out of the tap. Turn on the hot water, let some pour into a mug, then insert a food thermometer.

Are there other ways to alter the temperature of the water in your hot water cylinder?

If your hot water cylinder is an older model. Call us in to check that it is appropriately insulated. This will ensure that the water temperature isn’t dropping. (And will keep it safe as the cylinder can get quite hot to touch if it’s not insulated correctly).

Because there are key issues of safety and health risks involved with these matters of hot water cylinders and hot water cylinder temperature. We recommend you give the team at Cylinder Direct a call. We’ll gladly have a chat with you about the age and condition of your hot water cylinder. How to check the thermostat setting. Where to check for a tempering valve. And any other queries you may have.