What’s the best setting for a water heater?

How to choose the optimum settings for fuel efficiency and money saving.

This is a question asked on a regular basis. When people purchase new water heaters and the default setting is different to what they’re used to (aka too hot), they usually ask what they should adjust it to.

Should it be lukewarm? Only slightly hot? Very hot? Well, there are a multitude of factors to consider here, and that is why we’re going to run through them each one by one.

Firstly, it’s important that you understand why manufacturers actually set the default setting to be well over a safe temperature to bathe in. When you first purchase your water heater, you’re going to find that the water coming out of it is going to be incredibly hot. And that’s fantastic – you know that the machine you have just invested so much in can produce such hot water.

But if you’re not willing to pour that straight onto your back, why in the world would you have it set that high? All that you’re doing is wasting precious energy, which you are paying for. And why the heck would you do that? Manufacturers don’t set it high so that you waste energy – they don’t care. They just want to showcase the power of their products, and how well their design teams have worked.

But you don’t need to put up with that. Instead, what you should do is adjust the temperature on your water heater as soon as you get it delivered to your home and set up, and installed. If you’re purchased it for efficiency, you’re not really going to want to waste any energy.

With that said – what exactly is the best setting for a water heater? Well, the right answer is – there is no right answer. It entirely depends on the individual and how you like your water.

If you go to a tap right now, and turn on the hot water tap on it’s own, could you put your forearm underneath the flow without fear of burns? If not, that’s a sign you’re going to want to turn it all the way back down again.

Most people all over the world like their ‘hot’ water at a mild 120 fahrenheit, or about 48 degrees celsius. This is a temperature that won’t burn your arm, but it’ll certainly be hot.

If you want to get a temperature that is just right – perfect for you and fully adjusted to your preferences, we recommend you approach your water heater and turn the heat setting all the way down. Then, you should head to your nearest tap and open it’s hot water valve all the way. This will enable you to check the temperature of the water as you adjust the heater.

Then, incrementally crank up the temperature on your heater (this method works best with tankless heaters) and feel the water. If it’s too cold, crank it up again. You can repeat this process until you find the temperature that feels “just right” for a shower.

Once you have found this temperature, we strongly recommend that you edge it just a little bit higher than feels right, but not so high that it burns. This is because you might have some people in your household who do like a hotter shower than you do, and you should never revoke their freedom to have their showers just as they please.

Remember, you can always add some cold water if your shower feels too hot, but they won’t be able to add any hot water if their shower feels too cold.

However, if you’re still experiencing temperature problems, you may want to check your thermocouple in your water heater. If this is rusted or damaged, or covered in filth, you’re going to need to clean it and replace it. Call a plumber or do your own research on how to do this.

Now that you’ve adjusted the temperature on your water heating unit or system, it’s time to go and enjoy that shower you’ve been waiting for. And just to summarise, the process is as simple as gradually cranking up a dial until you feel the right temperature water falling from your tap.

About the author

Steve Bates

Hi, I'm Steve and I currently reside in Chicago, Illinois. Although for most of the last 20 years I was a partner in a HVAC company down in Austin, Texas.

I understand the frustration involved with dealing with water heater repairs and replacing or upgrading to a new, more efficient model.

My aim is offer some basic advice on fixing home hot water systems. And if a repair isn't possible, then to make the process of selecting a new water heater – be it gas or electric - as simple as possible.

So that you can save money and have a safe and reliable hot water system in your home for many years to come.